Seeds as Food

Some Definitions

Seeds and Health

Valuable Phytochemicals from Seeds

Problems Caused by Seeds

Seeds Are Common Food Allergens

Seeds and Food Poisoning

The Composition and Qualities of Seeds

Parts of the Seed

Seed Proteins: Soluble and Insoluble

Seed Starches: Orderly and Disorderly

Seed Oils

Seed Flavors

Handling and Preparing Seeds

Storing Seeds

Sprouts

Cooking Seeds

The Grains, or Cereals

Grain Structure and Composition

Milling and Refining

Breakfast Cereals

Wheat

Barley

Rye

Oats

Rice

Maize, or Corn

Minor Cereals

Pseudocereals

Legumes: Beans and Peas

Legume Structure and Composition

Legumes and Health: The Intriguing Soybean

The Problem of Legumes and Flatulence

Bean Flavor

Bean Sprouts

Cooking Legumes

Characteristics of Some Common Legumes

Soybeans and Their Transformations

Nuts and Other Oil-Rich Seeds

Nut Structures and Qualities

The Nutritional Value of Nuts

Nut Flavor

Handling and Storing Nuts

Cooking Nuts

Characteristics of Some Common Nuts

Characteristics of Other Oil-Rich Seeds

Seeds as Food

Seeds are our most durable and concentrated foods. They’re rugged lifeboats, designed to carry a plant’s offspring to the shore of an uncertain future. Tease apart a whole grain, or bean, or nut, and inside you find a tiny embryonic shoot. At harvest time that shoot had entered suspended animation, ready to survive months of drought or cold while waiting for the right moment to come back to life. The bulk of the tissue that surrounds it is a food supply to nourish this rebirth. It’s the distillation of the parent plant’s lifework, its gathering of water and nitrogen and minerals from the soil, carbon from the air, and energy from the sun. And as such it’s an invaluable resource for us and other creatures of the animal kingdom who are unable to live on soil and sunlight and air. In fact, seeds gave early humans both the nourishment and the inspiration to begin to shape the natural world to their own needs. Ten thousand turbulent years of civilization have unfolded from the seed’s pale repose.

The story began when inhabitants of the Middle East, Asia, and Central and South America learned to save some large, easily harvested seeds from wild plants, and sow them in clearings to produce more seeds of a similar kind. It appears that agriculture first arose in the highlands of southeastern Turkey, around the upper reaches of the Tigris and Euphrates rivers, and in the Jordan River valley. The first plants to be brought under human selection there were einkorn and emmer wheat, barley, lentil, pea, bitter vetch, and chickpea: a mixture of seed-bearing cereals and legumes. Gradually the nomadic life of the hunter-gatherer gave way to growing settlements alongside the large grainfields that fed them. The need arose for planning the sowing and the distribution of the harvests, for anticipating seasonal changes before they occurred, for organizing the work, and for keeping records. Some of the earliest known writing and arithmetical systems, dating from at least 5,000 years ago, are devoted to the accounting of grain and livestock. So the culture of the fields encouraged the culture of the mind. At the same time it brought problems, among them a drastic simplification of the hunter-gatherer’s varied diet and consequent damage to human health, and the development of a social hierarchy in which a few benefit from the labor of many.

In the Odyssey, Homer called wheat and barley “the marrow of men’s bones.” It’s less obvious to us in the modern industrialized world than it has been through much of human history, but seeds remain the essential food of our species. Grains directly provide the bulk of the caloric intake for much of the world’s population, especially in Asia and Africa. The grains and legumes together provide more than two-thirds of the world’s dietary protein. Even the industrial countries are fed indirectly by the shiploads of corn, wheat, and soybeans on which their cattle, hogs, and chickens are raised. The fact that the grains come from the grass family adds a layer of significance to the Old Testament prophet Isaiah’s admonishment that “All flesh is grass.”

As ingredients, seeds have much in common with milk and eggs. All consist of basic nutrients created to nourish the next generation of living things; all are relatively simple and bland in themselves, but have inspired cooks to transform them into some of the most complex and delightful foods we have.

Some Definitions

Seeds Seeds are structures by which plants create a new generation of their kind. They contain an embryonic plant together with a food supply to fuel its germination and early growth. And they include an outer layer that insulates the embryo from the soil and protects it from physical damage and from attack by microbes or animals.

The most important seeds in the kitchen fall into three groups.

Grains, or Cereals These words are near synonyms. The cereals (from Ceres, the Roman goddess of agriculture) are plants in the grass family, the Gramineae, whose members produce edible and nutritious seeds, the grains. But cereal is also used to mean their seeds and products made from them — as in “breakfast cereals” — and the plants are sometimes called grains. The cereals and other grasses are creatures of the open plain or high-altitude steppe, areas too dry for trees. They live and die in a season or two, and are easily gathered and handled. They grow in densely packed stands that crowd out competition, and produce many small seeds, relying on numbers rather than chemical defenses to ensure that some offspring will survive. These characteristics made the grasses ideal for agriculture. With our help, they have come to cover vast areas of the globe.

Wheat, barley, oats, and rye have been the most important grains in the Middle East and Europe; in Asia, rice; in the New World, maize, or corn; in Africa sorghum and millets. The grains are of special culinary significance because they make possible beer and bread, both staples in the human diet for at least 5,000 years.

An oat kernel, lentils in their pod, and a hazelnut. All are seeds, and consist of a living embryonic plant together with a food supply to fuel its early growth. In the cereal grains, the food supply is a separate tissue, the endosperm. In the beans and their relatives, and in most nuts, the food supply fills the first two leaves of the embryo, the cotyledons, which are unusually massive and thick.

Legumes The legumes (from the Latin legere, “to gather”) are plants in the bean family, the Leguminosae, whose members bear pods that contain several seeds. The term legume is also used to name their seeds. Many legumes are vines that climb on tall grasses and other plants to reach full sunlight, and like the grasses grow, go to seed, and die over a few months. The legumes produce seeds that are especially rich in protein, thanks to their symbiosis with bacteria that live in their roots and feed them with nitrogen from the air. The same symbiosis means that legumes actually enrich the soil they grow in with nitrogen compounds, which is why various legumes have been grown as rotation crops at least since Roman times. Their relatively large seeds are attractive to animals, and it’s thought that much of the remarkable diversity in the beans and peas is the result of survival pressures exerted by insects. Legume seeds are camouflaged by colored coats, and protected with an array of several biochemical defenses.

Lentils, broad beans, peas, and chick peas are all native to the Fertile Crescent of the Near East. They were adapted for sprouting and quickly reproducing in the cool, wet season before the summer drought, and were the first substantial foods to ripen in the spring. The soy and mung beans were indigenous to Asia, and peanuts, lima beans, and common beans to the Americas.

Nuts The nuts (from an Indo-European root meaning “compressed”) come from several different plant families, not just one. They are generally large seeds enclosed in hard shells, and borne on long-lived trees. The seeds are large both to make them attractive to animal dispersers (which bury some for later use and effectively plant the ones they forget), and to give the seedling an adequate food supply for slow, prolonged growth in the partial shade. Most of them store their energy not in starch but in oil, a more compact, concentrated chemical form (p. 121).

Nuts are much less important in the human diet than grains or legumes because nut trees don’t begin to bear until years after they’re planted, and can’t produce as much per acre as the quick-growing grains and legumes. The biggest exception to this rule is the coconut, a staple food in many tropical countries. Another is the peanut, which is a legume with an uncharacteristically oily, tender seed, and which can be grown quickly in massive numbers.

Seeds and Health

Our seed foods provide us with many nutritional benefits. To begin with, they’re our most important staple sources of energy and protein, and carry the B vitamins that are required for the chemical work of generating energy and building tissue. In fact, they’re such a good source of these essential nutrients that cultures have occasionally relied on the grains too heavily, and suffered from dietary deficiencies as a result. The debilitating disease called beriberi plagued rice-eating Asia in the 19th century when milling machines made it easier to remove the inconvenient, unattractive outer bran layer from rice grains — and along with it their thiamin, which the rest of the largely vegetarian diet couldn’t make up (meats and fish are rich in thiamin). A different deficiency disease called pellagra struck the rural poor in Europe and the southern United States in the 18th and 19th centuries, when they adopted corn from Central and South America as a staple food, but without the processing method (cooking in alkaline water) that makes its stores of niacin available to the human body.

Beriberi and pellagra led early in the 20th century to the discovery of the vitamins whose deficiencies cause them. Today, even though most people in Asia eat refined rice, and polenta and grits are still not cooked in alkaline water, more balanced diets have made these deficiency diseases far less common.

Valuable Phytochemicals
From Seeds

Toward the end of the 20th century, we came to realize that seeds have more to offer us than the basic machinery of life. Epidemiological studies have found a general association between the consumption of whole grains, legumes, and nuts and a reduced risk of various cancers, heart disease, and diabetes. What do these foods provide that refined grains do not? Hundreds or even thousands of chemicals that are concentrated in the outer protective and active layers of the seeds, and that are not found in inner storage tissues, which are mainly depots of starch and protein. Among the chemicals that have been identified and seem likely to be helpful are

• a variety of vitamins, including antioxidant vitamin E and its chemical relatives the tocotrienols
• soluble fiber: soluble but undigestible carbohydrates that slow digestion, moderate blood insulin and blood sugar levels, and reduce cholesterol levels, and provide energy for beneficial intestinal bacteria, which alter their chemical environment, suppress the growth of harmful bacteria, and influence the health of intestinal cells
• insoluble fiber, which speeds passage of food through the digestive system and reduces our absorption of carcinogens and other undesirable molecules
• a variety of phenolic and other defensive compounds, some of which are effective antioxidants, some of which resemble human hormones and may restrain cell growth and thereby the development of cancer

Medical scientists are still in the early stages of identifying and evaluating these substances, but in general it looks as though regular consumption of whole grains, legumes, and nuts can indeed make a real contribution to our long-term health.

Problems Caused by Seeds

Seeds are not perfect foods. Legumes in particular contain defensive chemicals — lectins and protease inhibitors — that can cause malnourishment and other problems. Fortunately, simple cooking disarms these defenses (p. 259). The fava bean contains amino-acid relatives that cause serious anemia in susceptible people (p. 490), but both the bean and the susceptibility are relatively rare. Two other problems are more common.

Seeds are Common
Food Allergens

True food allergies are overreactions of the body’s immune system, which mistakes a food component as a sign of invasion by a bacterium or virus and initiates a defense that damages the body. The damage may be mild and manifest itself as discomfort, itchiness, or a rash, or it may be a life-threatening asthma or change in blood pressure or heart rhythm. It’s estimated that about 2% of adults in the United States have one or more food allergies, and up to 8% of young children. Allergic reactions to food cause around 200 deaths per year in the United States. Peanuts, soybeans, and tree nuts are among the most common food allergens. The offending components are usually seed proteins, and cooking does not render them less allergenic. Tiny quantities of nut proteins are sufficient to cause reactions, including the levels sometimes found in mechanically extracted nut oils.

Gluten Sensitivity A special form of food allergy is the disease called gluten-sensitive enteropathy, celiac disease, or sprue, in which the body forms defensive antibodies against a portion of the harmless gliadin proteins in wheat, barley, rye, and possibly oats. These defenses end up attacking the nutrient-absorbing cells in the intestine, and therefore cause serious malnourishment. Celiac disease can develop in early childhood or later, and is a lifelong condition. The standard remedy is strict avoidance of all gluten-containing foods. Several grains don’t contain gliadin proteins and therefore don’t aggravate celiac disease; they are corn, rice, amaranth, buckwheat, millet, quinoa, sorghum, and teff.

Seeds and Food Poisoning

Seeds are generally dry, with only about 10% of their weight coming from water. As a result, they keep well without special treatment; and because we prepare them by thoroughly boiling or roasting them, freshly cooked grains, beans, and nuts generally don’t carry bacteria that cause food poisoning. However, moist grain and bean dishes become very hospitable to bacteria as they cool down. Leftovers should be refrigerated promptly and reheated to the boil before serving. Rice dishes are particularly vulnerable to contamination by Bacillus cereus and require special care (p. 475).

Even dry seeds aren’t entirely immune to contamination and spoilage. Molds, or fungi, are able to grow with relatively little moisture, and can contaminate seed crops both in the field and in storage. Some synthesize deadly toxins that can cause cancer and other diseases (for example, species of Aspergillus produce a carcinogen called aflatoxin, and Fusarium moniliforme produces another called fumonisin). The presence of fungal toxins in our foods is generally invisible to the consumer, and is monitored by producers and government agencies. They’re not now considered a major health risk. But the least sign of mold or other spoilage on grains and nuts means that the food should be discarded.

The Composition
and Qualities of Seeds

Parts of the Seed

All of our food seeds consist of three basic parts: an outer protective coat, a small embryonic portion capable of growing into the mature plant, and a large mass of storage tissue that contains proteins, carbohydrates, and oils to feed the embryo. Each part influences the texture and flavor of the cooked seeds.

The outer protective coat, called the bran in grains and the seed coat in legumes and nuts, is a dense sheet of tough, fibrous tissue. It’s rich in defensive or camouflaging phenolic compounds, including anthocyanin pigments and astringent tannins. And it slows the passage of water into grains and legumes during cooking. It’s often removed from grains (especially rice and barley), legumes (notably in Indian dals), and nuts (almonds, chestnuts) to speed the cooking and obtain a more refined appearance, texture, and flavor.

The embryonic portion of legumes and nuts is not of much practical significance, but the germ of the grains is: it contains much of the oil and enzymes in these seeds, and thus is the source of potential flavor, both desirable cooked aromas and undesirable stale ones.

The bulk of the seed is a mass of storage tissue, and its makeup determines the seed’s basic texture. The storage cells are filled with particles of concentrated protein, granules of starch, and sometimes with droplets of oil. In some grains, notably barley, oats, and rye, the cell walls are also filled with storage carbohydrates — not starch, but other long sugar chains that like starch can absorb water during cooking. The strength of the cement that holds the storage cells together, and the nature and proportions of the materials they contain, determine the seed’s texture. Bean cells and grain cells are filled with solid, hard starch granules and protein bodies; most nut cells are filled with liquid oil, and so are more fragile. Grains retain their shape and some firmness even when we mill away their protective bran envelope and boil them in plenty of water. Beans remain intact as long as we cook them in their seed coats; otherwise they rapidly disintegrate into a puree.

The particular contents of the seed storage cells influence texture and culinary usefulness in a number of ways. So it’s worth knowing about the proteins, starches, and oils in some detail.

Seed Proteins: Soluble and Insoluble

Seed proteins are classified by a particular aspect of their chemical behavior, which also determines their behavior during cooking: the kind of liquid in which they dissolve. This may be pure water, water and some salt, water and dilute acid, or alcohol (these types are called “albumins,” “globulins,” “glutelins,” and “prolamins”). Most of the proteins in legumes and nuts are soluble in a salt solution or water alone, so during ordinary cooking in salted water, bean and pea proteins become dispersed in the moisture within the seeds and the cooking liquid surrounding them. By contrast, the main storage proteins in wheat, rice, and other grains are acid-soluble and alcohol-soluble types. In ordinary water, these proteins don’t dissolve; instead they bond to each other and clump up into a compact mass. Wheat, rice, corn, and barley kernels develop a chewy consistency in part because their insoluble proteins clump together in the grain during cooking and form a sticky complex with the starch granules.

Seed Starches: Orderly and Disorderly

All the grains and legumes contain a substantial amount of starch, enough that it plays a significant role in the texture of the cooked seeds and their products. It can make one grain variety behave very differently from another variety of the same grain.

Two Kinds of Starch Molecules The parent plant lays down starch molecules in microscopic, solid granules that fill the cells of the seed storage tissue. All starch consists of chains of individual molecules of the sugar called glucose (p. 804). But there are two different kinds of starch molecules in starch granules, and they behave very differently. Amylose molecules are made from around 1,000 glucose sugars, and are mainly one extended chain, with just a few long branches. Amylopectin molecules are made from 5,000 to 20,000 sugars and have hundreds of short branches. Amylose is thus a relatively small, simple molecule that can easily settle into compact, orderly, tightly bonded clusters, while amylopectin is a large, bushy, bulky molecule that doesn’t cluster easily or tightly. Both amylose and amylopectin are packed together in the raw starch granule, in proportions that depend on the kind and variety of seed. Legume starch granules are 30% or more amylose, and wheat, barley, maize, and long-grain rice granules are around 20%. Short-grain rice granules contain about 15% amylose, while “sticky” rice starch granules are almost pure amylopectin.

The Proportions of Proteins in Seeds

Cooking Separates Starch Molecules and Softens Granules When a seed is cooked in water, the starch granules absorb water molecules, and swell and soften as the water molecules intrude and separate the starch molecules from each other. This granule softening, or gelation, takes place in a temperature range that depends on the seed and starch, but is in the region of 140–160ºF/60–70ºC. (The conversion of solid starch into a starch-water gel is often referred to as “gelatinization,” but this is unnecessarily confusing; starch has nothing to do with gelatin.) The tightly ordered clusters of amylose molecules require higher temperatures, more water, and more cooking time to be pulled and kept apart than do the looser clusters of amylopectin molecules. This is why long-grain Chinese rices are made with more water than short-grain Japanese rices.

Cooling Reorganizes Starch Molecules and Firms Granules Once the cooking is finished and the seeds cool down below the gelation temperature, the starch molecules begin to re-form some clusters with pockets of water in between, and the soft, gelated starch granules begin to firm up again. This process is called retrogradation. The simpler amylose molecules start bonding to each other again almost immediately, and finish within a few hours at room or refrigerator temperatures. Sprawling, bushy amylopectin molecules take a day or more to reassociate, and form relatively loose, weak clusters. This difference explains why long-grain rices high in amylose have a firm, springy texture when served right after cooking and get inedibly hard when refrigerated overnight, while short-grain rices low in amylose have a softer, sticky texture and harden much less during overnight refrigeration. The hardness of all leftover grains can be largely remedied simply by reheating and so regelating their starch.

Starch gelation and retrogradation. Starch granules are compact, organized masses of long starch chains (left) . When a starchy cereal is cooked, water penetrates the granule and separates the chains from each other, thus swelling and softening the granule in the process called gelation (center) . When the cooked cereal cools down, the starch chains slowly rebond to each other in tighter, more organized associations, and the granule becomes firmer and harder, a process called retrogradation (right).

Starch Firming Can Be Useful Reheated grains never get quite as soft as they were when first cooked. This is because during the process of retrogradation, amylose molecules manage to form some clusters that are even more highly organized than the clusters in the original starch granule, crystalline regions that resist breaking even at boiling temperatures. These regions act as reinforcing junctions in the overall network of amylose and amylopectin molecules, and give the granules greater strength and integrity. Cooks take advantage of this strengthening to make bread puddings and starch noodles; parboiled (converted) rice and American breakfast cereals keep their shape because much of their starch has been allowed to retrograde during manufacturing. And it turns out that retrograded starch is good for our bodies! It resists our digestive enzymes and therefore slows the rise in blood sugar following a meal, and feeds desirable bacteria in the large intestine (p. 258).

Seed Oils

Nuts and soybeans are rich in oil, which is kept in the mass of storage tissue in tiny packages called oil bodies. Each is a tiny oil droplet whose surface is covered with two protective materials: phospholipid relatives of lecithin, and proteins called oleosins. The surface coating prevents the oil droplets from pooling together. Seed oil bodies are very similar in size and structure to the fat globules in animal milk. This is why when we eat nuts, they become creamy in the mouth rather than simply greasy. It’s also one reason why for a thousand years cooks have made “milks” from almonds, soybeans, and other oil-rich seeds (pp. 494, 504).

Seed Flavors

The most important contributors to the flavors of grains, legumes, and nuts are fragments of the unsaturated fatty acids in the oils and cell membranes, which have individual aromas described as green, fatty, oily, floral, and mushroomy. The outer bran layer grains contains the bulk of the seed’s oils and enzymes, and so gives whole grains a stronger flavor, as well as contributing some vanilla and toasted notes from its phenolic compounds. Beans are especially rich in green and mushroom notes. Nuts, which are usually cooked with dry heat, contain products of the browning reactions with typical roasted aromas. The flavors of particular seeds are described below.

Handling and
Preparing Seeds

Preparations of particular seeds are described in more detailed surveys below. Here are some common aspects of using seeds in the kitchen.

Storing Seeds

Because most of the seeds we eat are designed to survive a dormant, dry period, they are the easiest food ingredients to store. Whole seeds keep well for months in a dry, cool, dark place. Moisture encourages the growth of spoilage microbes, and physical damage, heat and light can accelerate the oxidation of seed oils that leads to stale, rancid aromas and bitter tastes.

The pest that sometimes infests grains, beans, nuts, and flours is the Indian meal moth (Plodia interpunctella). It originally came from ears of grain in the field but is now a common inhabitant of our pantries, where its eggs hatch into larvae that consume the seeds and generate unpleasant smells. There’s nothing to do with a contaminated batch but discard it. Keeping seeds in separate glass or plastic jars will prevent one batch from contaminating another.

Sprouts

The sprouted seed is a culinary custom of ancient lineage in Asia, but a very recent arrival in the West. Thanks to the sprout, anyone, anytime — even an apartment-dweller in Anchorage in February — can raise a good approximation to fresh vegetables with very little effort. Sprouting often improves a seed’s vitamin content and digestibility. And with their nutty flavor and crisp texture, sprouts are simply a nice change from the usual vegetables.

Beans are most commonly sprouted, but many of our food seeds can be sprouted to advantage. Sprouted wheat and barley, for example, develop a sweetness as their enzymes begin to break down stored starch into sugars for the embryonic plant. Sprouts have a nutritional value midway between that of the dry seed, which they just were, and a leafy green vegetable, which they’re on the way to becoming. Sprouts are higher in vitamin C and lower in calories than most seeds, and higher than most vegetables in protein (5% versus about 2%) and in the B vitamins and iron.

Cooking Seeds

Seeds are the driest and hardest ingredients that cooks deal with. Most require both moisture and heat to make them edible. Most, but not all: the nuts are generally edible and nutritious fresh out of the shell or after a brief application of dry heat, thanks to their relatively tender cell walls and the cells’ content of liquid oil rather than solid starch. But dry grains and legumes are hard and starchy. Hot water softens them by dissolving the strengthening carbohydrates from their cell walls, and moving into the cells to gelate the starch granules and either dissolve or moisten the storage proteins. This makes the seed more nutritious by exposing its nutrients to our digestive enzymes.

There are a few simple facts to remember about cooking grains and legumes in water.

• The outer bran layer or seed coat is designed to control the passage of soil moisture into the embryo and storage tissues during germination. It also slows the passage of cooking water. Seeds that have been milled free of their coats or into small pieces cook much faster than whole seeds.
• Heat penetrates seeds faster than water can, so much of the cooking time is moistening time. Presoaking seeds for a few hours or overnight can cut cooking times by half or more.
• Most seeds get quite soft when they’ve absorbed enough liquid to be about 60–70% water by weight. That quantity of water is the equivalent of about 1.7 times the dry weight of the seeds, or about 1.4 times their volume. Recipes generally call for much more water than this to allow for water lost to evaporation during cooking.
• The texture of fully cooked seeds is soft and fragile at cooking temperatures, but firms during cooling. If an intact appearance is important, it’s good to let grains and legumes cool down before handling them.

Of course the most important grain and legume foods are made from finely ground flours or extracts. Mix water with ground grains or with starch extracted from beans and the result is a dough or batter, which heat can turn into noodles or flat breads or cakes. Aerate doughs or batters with the help of yeasts or bacteria or chemical leaveners, and the result is raised breads and cakes. Doughs and batters are special materials in their own right, and are described in detail in the next chapter.

Seeds Concentrate Cooking Liquids Because grains and beans are dry and soak up water, they remove water from the liquid they’re cooked in, and therefore effectively concentrate other materials in the liquid. In this way they create a sauce for themselves. When rice or polenta is cooked in milk, for example, the liquid between the grains becomes richer in both milk proteins and fat globules, and so more like cream. When grains are cooked in a meat stock, the stock become more concentrated in gelatin, and so comes to resemble a reduced stock or demiglace.

The Grains, or Cereals

Of the approximately 8,000 species in the grass family, only a handful play a significant role in the human diet. Aside from bamboo and sugar cane, these are the cereals. While their grains are very similar in structure and composition, the differences have made for widely divergent culinary histories.

The major Eurasian cereals — wheat, barley, rye, and oats — originally grew wild in extensive stands on the temperate high plains of the Near East. Groups of early humans could harvest enough wheat and barley from these wild fields in a few weeks to sustain themselves for a year. Some 12,000 to 14,000 years ago, the first agriculturalists began to plant and tend wheat and barley seeds selected for their size and the ease with which they could be harvested and used; and farmers gradually spread these crops throughout western and central Asia, Europe, and north Africa. Each cereal had its advantages. Barley was especially hardy, while rye and oats were able to adapt to wet, cold climates, and wheat produced a uniquely elastic paste that could be filled with tiny bubbles and baked into tender raised breads. Around the same time, the inhabitants of tropical and semitropical Asia domesticated rice, with its special ability to grow in wet, hot growing conditions. Somewhat later in warm central and South America arose maize, or corn, whose plants and kernels dwarf those of the other cereals.

Grain Structure
and Composition

The edible portion of the cereal plant, commonly called the grain or kernel, is technically a complete fruit whose ovary-derived layer is very thin and dry. Three of the cereals — barley, oats, and rice — bear fruits that are covered by small, tough, leaf-like structures that fuse to form the husk or hull. Bread and durum wheats, rye, and maize bear naked fruits and don’t have to be husked before milling.

All the grains have the same basic structure. The fruit tissue consists of a layer of epidermis and several thin inner layers, including the ovary wall; altogether, it’s only a few cells thick. Just underneath the seed coat is the aleurone layer, only one to four cells thick and yet containing oil, minerals, protein, vitamins, enzymes, and flavor out of proportion to its size. The aleurone layer is the outer layer and only living part of the endosperm; the rest is a mass of dead cells that stores most of the carbohydrates and protein, and that takes up most of the grain’s volume. Abutting onto the endosperm from one side is the scutellum, a single modified leaf that absorbs, digests, and conducts food from the endosperm to the embryo, or “germ,” which is at the base of the fruit, and which is also well endowed with oil, enzymes, and flavor.

The endosperm (from the Greek: “within the seed”) is often the only part of the grain consumed. It consists of storage cells that contain starch granules embedded in a matrix of protein. This matrix is made up of normal cell proteins and membrane materials, and sometimes of spherical bodies of special storage proteins which, squeezed together as the starch granules grow, lose their individual identity and form a monolithic mass. There’s generally more starch and less protein per cell near the center of the grain than there is near the surface. This gradient means that the more grains are refined by milling and polishing, the less nutritious they get.

Milling and Refining

People began treating the grains to remove their tough protective layers in prehistoric times. Milling breaks the grains into pieces, and refining sifts away the bran and germ. The very different mechanical properties of endosperm, germ, and bran make this separation possible: the first is easily fragmented, and the others are oily and leathery respectively. The germ and the bran — which in practice include the aleurone layer just underneath it — together account for most of the fiber, oil, and B vitamins contained in the whole grain, as well as some 25% of its protein. Yet these parts of the grain are usually removed entirely or in part from rice and barley grains, and from cornmeal and wheat flours. Why this waste? Refined grains are easier to cook and to chew, and more attractively light in color. And in the case of flours, the high lipid concentrations in the germ and aleurone layer shorten the shelf life of whole-grain flours substantially. The oils are susceptible to oxidation and develop rancid flavors (stale aroma, harsh taste) in a matter of weeks. Today most refined cereals in industrial countries are fortified with B vitamins and iron in order to compensate for the nutrients lost with the bran.

Breakfast Cereals

Apart from breads and pastries, the most common form in which Americans consume grain is probably the breakfast cereal. There are two basic types of breakfast cereals: hot, which require cooking, and ready-to-eat, which are eaten as is, often with some cold milk.

The anatomy of a wheat kernel. It’s a miniature but complete fruit, with a dry rather than fleshy ovary wall. The large mass of endosperm cells stores food to nourish the early growth of the embryo or “germ.”

Hot Cereals Hot cereals have been eaten since the dawn of civilization in the form of gruels, porridges, and congees. Corn grits, oatmeal, and cream of wheat are modern examples. Cooking the whole or milled cereal in excess of hot water softens the cell walls, gelates the starch grains and leaches starch molecules out, and produces a digestible, bland mush. The only significant improvement brought by the machine age has been a reduction in cooking time, either by grinding the cereal finely enough that it’s quickly cooked, or by partly precooking it. it

Ready-to-Eat Cereals Ready-to-eat cereals are the more common breakfast cereal by far in the United States. Ironically, the industry that has come under fire for giving children little more than empty calories, a sort of early-morning junk food, began as a “pure” and “scientific” health food, an alternative to the destructive diet of turn-of-the-century America. Its story involves a uniquely American mix of eccentric health reformers, fringe religion, and commercial canniness.

In the middle third of the 19th century, a vegetarian craze arose in opposition to the diet of salt beef and pork, hominy, condiments, and alkali-raised white bread that was prevalent at the time. A pure, plain diet for America was the object, and the issue was not only medical but moral. As Dr. John Harvey Kellogg put it somewhat later in his Plain Facts for Old and Young, “A man that lives on pork, fine-flour bread, rich pies and cakes, and condiments, drinks tea and coffee, and uses tobacco, might as well try to fly as to be chaste in thought.” Kellogg and his brother Will Keith Kellogg, C. W. Post, and others invented such virtuous preparations as shredded wheat, wheat and corn flakes, and Grape Nuts. These precooked cereals did offer a light, simple alternative to the substantial breakfasts of the day, became widely popular, and quickly generated a large, inventive, and profitable industry. Today there are several major varieties of ready-to-eat cereals:

• Muesli is a simple mixture of thinly rolled grains, sugar, dried fruits, and nuts.
• Flakes are made from whole grains (wheat) or grain fragments (corn) that are flavored, steam-cooked, cooled, rolled into thin flakes, and toasted in a drum oven.
• Granola, a term coined by the Kelloggs 100 years ago, is now rolled oats flavored with sweeteners (honey, malt, sugar) and spices, enriched with vegetable oil, toasted and mixed with nuts and/or dried fruit.
• Oven-puffed rice and corn are made by cooking rice grains or corn grits with water and flavorings, partly drying and lightly rolling them, then toasting in an oven that may reach 650ºF/340ºC, when the remaining moisture evaporates quickly enough to expand the grain structure.
• Puffed rice and wheat are made from whole grains, which are wetted and enclosed in a pressure-cooker “gun” at a temperature of 500–800ºF/260– 430ºC. The steam pressure reaches 14 atmospheres, and is suddenly released, expelling the grains. As the steam within the grains expands from the pressure drop, it expands the grain structure, which then sets as it cools down into a light, porous mass.
• Baked cereals follow in the mold of the 19th century original, C. W. Post’s Grape Nuts: dough of some sort is formed, baked, sometimes granulated and rebaked.
• Extruded cereals, usually small crunchy shapes, are made from doughs that are forced at high pressure through small openings, much as dried pastas are made. The pressure and friction generate high temperatures that cook the dough as it’s shaped, and the pressure drop as the formed dough exits the extruder can cause it to expand as well.

Grains are still the base for these cereals, but they may actually be outweighed by sugar and other sweeteners. Sucrose is especially favored for its ability to give a frosty or glassy surface to the crisp grain flakes and slow the penetration of milk and resulting sogginess.

Wheat

Wheat was one of the first food plants to be cultivated by humans, and was the most important cereal in the ancient Mediterranean civilizations. After a long hiatus from the Middle Ages to the 19th century, when hardier but less versatile cereals and potatoes were the principal staple foods, it regained its preeminence in much of Europe. Wheat was brought to America early in the 17th century and had reached the Great Plains by 1855. Compared to other temperate-zone cereals, wheat is a demanding crop. It’s susceptible to disease in warm, humid regions and does best in a cool climate, but it can’t be grown as far north as rye and oats.

Ancient and Modern Wheats A handful of different wheats have been grown from prehistoric times to the present. Their evolution is fascinating and still somewhat mysterious, and is summarized in the box on p. 466. The simplest wheat and one of the first to be cultivated was einkorn, which had the standard genetic endowment of most plants and animals: namely two sets of chromosomes (a “diploid” species). Somewhat less than a million years ago, a chance mating of a wild wheat with a wild goatgrass produced a wheat species with four sets of chromosomes, and this “tetraploid” species gave us the two most important wheats of the ancient Mediterranean world, emmer and durum. Then, just 8,000 years ago, another unusual mating between a tetraploid wheat species and a goatgrass gave an offspring with six sets of chromosomes: and this offspring gave us our modern bread wheats. The extra chromosomes are thought to contribute to the agricultural and culinary diversity found in modern wheats, most importantly the elasticity of the gluten proteins. Today 90% of the wheat grown in the world is hexaploid bread wheat. Most of the remaining 10% is durum wheat, whose main purpose is making pasta (p. 571). The other wheats are still cultivated on a small scale.

Durum Wheat Durum wheat, T. turgidum durum, is the most important of the tetraploid wheats. It arose in the Near East and spread to the Mediterranean before Roman times, when it was one of two major wheats. Emmer was better suited to humid climates and had a starchy grain, while durum was better suited to semiarid conditions and had a glassy grain. Both were used to make breads leavened and unleavened, bulgur, couscous, injera, and other preparations. Southern and central Italy is now the main producer in Europe; India, Turkey, Morocco, Algeria, and the United States and Canada are large producers elsewhere.

Einkorn Wheat Einkorn wheat, T. monococcum, was rediscovered in the early 1970s in the Vaucluse region of France and the southern Alps, where it was being grown to make a local porridge. It was probably the first wheat to be cultivated, around 10,000 years ago. It grows best in cool conditions, tends to be rich in yellow carotenoid pigments and is high in protein. However, where the proportions of elastic glutenin and flowing gliadin (p. 521) are 1 to 1 in bread wheat, in einkorn they’re 1 to 2. The result is a sticky, fluid gluten that’s unsuited to breadmaking.

Emmer Wheat or Farro Emmer wheat, T. turgidum dicoccum, was probably the second wheat to be cultivated. It grew in warmer climates than einkorn, and became the most important cultivated form from the Near East through northern Africa and Europe until early Roman times, when it was superseded by durum and bread wheats. But pockets of emmer cultivation survived in parts of Europe, and emmer is now widely available under its Italian name, farro. In Tuscany whole farro grains go with beans into a winter soup; the pre-soaked grains are also made into a risotto-like dish called farrotto.

Kamut Kamut is the registered trademark for an ancient relative of durum wheat, a subspecies of T. turgidum. The modern production and commercialization of kamut (Egyptian for “wheat”) began after World War II, when seeds said to have been collected in Egypt were planted in Montana. It’s characterized by a large grain size and a high protein content, though its gluten is better suited to pasta than to raised breads.

Spelt Spelt, T. spelta became known as Dinkel in southern Germany, where it has been grown since 4000 BCE. It’s often confused with emmer (farro). Spelt is remarkable for its high protein content, as much as 17%. It’s still used to make breads and soups. Central Europeans make Grünkern, or “green kernel,” by gently drying or roasting the green grain and milling it for use in soups and other preparations.

Varieties of Bread and Pasta Wheats Something on the order of 30,000 varieties of wheat are known, and they’re classified into a few different types according to planting schedule and endosperm composition. They’re mostly used to make breads, pastries, and pastas, and are described in the next chapter.

Wheat Pigments Most wheat varieties have a reddish-brown bran layer that owes its color to various phenolic compounds and to browning enzymes (p. 269) that assemble them into large colored aggregates. Less common are white wheats, whose bran layer is cream-colored due to a much lower content of phenolic compounds and browning enzymes. White wheats have a less astringent taste and discolor less when some of the bran is included in the flour; they’re used to replace ordinary wheats when an especially mild flavor or light color is desired.

The color of durum wheat, its coarse semolina flour, and dry pasta is due mainly to the carotenoid xanthophyll lutein, which can be oxidized to a colorless form by enzymes in the grain and oxygen. This maturation has traditionally been desired in wheats (remember that the name comes from an ancient root meaning “white”), but is not in durum. Some of the minor wheats are also rich in carotenoid pigments.

Wheat Gluten

Gluten in Wheat Flour Doughs Wheat has long been the West’s premier grain primarily because its storage proteins have unique chemical properties. When flour is mixed with water, the gluten proteins bond to each other and form an elastic mass that can expand to accommodate gas bubbles produced by yeast. Without wheat, then, we would not have raised breads, cakes, and pasta as we know them. Gluten quantity and quality vary significantly among different wheats, and determine the uses to which a given type is put.

Gluten as a Separate Ingredient Because they’re both cohesive and insoluble in water, the gluten proteins are easily separated from the rest of the flour: you simply make a dough, then knead it in water. The starch and water-soluble substances wash away, and tough, chewy gluten remains. Gluten as a unique food ingredient was discovered by Chinese noodle makers around the 6th century, and by the 11th was known as mien chin, or the “muscle of flour.” (The Japanese call it seitan.) When cooked, concentrated gluten does develop a chewy, slippery texture like that of meats from animal muscle. Mien chin became a major ingredient in the vegetarian cooking that developed in Buddhist monasteries; there are recipes dating from the 11th century for imitation venison and jerky, and for fermented gluten. Because gluten contains a high proportion of glutamic acid, fermentation breaks it down into a condiment that was an early version of savory-tasting MSG (p. 342). One of the simplest ways to prepare gluten is to pinch off small bits and deep-fry them; they puff up into light chewy balls that readily absorb the flavor from a sauce. Today gluten is widely available and used to make a variety of vegetarian “meats.”

Notable Wheat Preparations Whole grains of wheat, often called wheat berries, are usually sold with their bran fully intact, and can take an hour or more to cook unless presoaked. Farro is now available with part of its bran milled away — similar to partly milled pigmented rice and wild rice — and cooks much more quickly, while retaining the stronger flavor and integrity of separate grains provided by the bran.

Wheat germ is sometimes added to baked goods or other foods; it is a good source of protein (20% by weight), oil (10%), and fiber (13%). Wheat bran is mainly fiber, with about 4% oil. Their oil content makes both bran and germ susceptible to developing stale flavors. They’re best stored in the refrigerator.

Bulgur Bulgur or burghul is an ancient preparation of wheat — usually durum — that’s still popular in North Africa and the Middle East. It’s made by cooking whole grains in water, drying them so that the interior becomes glassy and hard, then moistening them to toughen the outer bran layer, and finally pounding or milling to remove the bran and germ and leave the endosperm in coarse chunks. It’s the wheat version of parboiled rice (p. 473). The result is a nutritious form of wheat that keeps indefinitely and cooks relatively quickly. Coarse bulgur (to 3.5 mm across) is used much as rice or couscous is, boiled or steamed to go with a moist dish or made into a pilaf or a salad, while fine bulgur (0.5–2 mm) is made into falafel (deep-fried balls of bulgur and fava-bean flour), and various pudding-like sweets.

Green, or Immature Wheat Green wheat grains have also been enjoyed for their sweetness and unusual flavor. The stalks are cut while the grains are still moist inside, the grains charred over a small straw fire to weaken the husks and add flavor, then eaten fresh or dried for keeping (Turkish firig, Arab frikke).

Barley

Barley, Hordeum vulgare, may have been the first cereal to be domesticated in the grasslands of southwest Asia, where it grew alongside wheat. It has the advantage of a relatively short growing season and a hardy nature; it’s grown from the Arctic Circle to the tropical plains of northern India. It was the primary cereal in ancient Babylon, Sumeria, Egypt, and the Mediterranean world, and was grown in the Indus valley civilization of western India long before rice. According to Pliny, barley was the special food of the gladiators, who were called hordearii, or “barley eaters”; barley porridge, the original polenta, was made with roasted flaxseed and coriander. In the Middle Ages, and especially in northern Europe, barley and rye were the staple foods of the peasantry, while wheat was reserved for the upper classes. In the medieval Arab world, barley dough was fermented for months to produce a salty condiment, murri, that food historian Charles Perry has discovered tastes much like soy sauce.

Today, barley is a minor food in the West; half of production is fed to animals, and a third is used in the form of malt. Elsewhere, barley is made into various staple dishes, including the Tibetan roasted barley flour tsampa, often eaten simply moistened with tea; it’s an important ingredient in the Japanese fermented soy paste miso; and in Morocco (the largest per capita consumer) and other countries of north Africa and western Asia it’s used in soups, porridges, and flat breads. In Ethiopia there are white, black, and purple-grained barleys, some of which are made into drinks. Water simmered with raw or roasted barley has been enjoyed for two thousand years or more, from western Europe to Japan.

The barley grain is notable for containing significant quantities — about 5% each of the grain weight — of two carbohydrates other than starch: the pentosans that give rye flours their stickiness, and the glucans that give oats their gelatinous and cholesterol-lowering qualities (pp. 470, 471). Both are found in the walls of endosperm cells as well as in the bran, and together with barley’s water-insoluble proteins they contribute to the distinctively springy texture of the cooked grain. They also cause barley flour to absorb twice the water that wheat flour does.

Pearled Barley There are hull-less barleys, but most food varieties have adherent hulls that are removed as part of the milling process. Barley has more of its grain removed than does rice, the other grain frequently prepared as a whole grain. This is partly because barley bran is brittle and doesn’t come off in large flakes, so it can’t be removed during normal milling; and partly because processors eliminate the deep crease in the barley grain to give it a more uniform appearance. The process of “pearling” in a stone mill removes the hull and then portions of the bran. “Pot barley” has lost 7–15% of the grain, but retains the germ and some of the bran, and so more nutrients and flavor. Fine pearled barley has lost the bran, germ, and aleurone and subaleurone layers, a loss of about 33% of the grain’s initial weight.

Barley Malt The most important form in which we consume barley is malt, a major ingredient in beers and some distilled liquors, and a minor ingredient in many baked goods. Malt is a powder or syrup made from barley grains that are moistened and allowed to germinate, and that become sweet with sugars. Its production and qualities are described below (pp. 679, 743).

Rye

Rye apparently arose in southwest Asia, migrated with domesticated wheat and barley as a weed in the crops of early farmers, reached the coast of the Baltic Sea around 2000 BCE, grew better than the other cereals in the typically poor, acid soil and cool, moist climate, and was domesticated around 1000 BCE. It’s exceptionally hardy, and is grown as far north as the Arctic Circle and as high as 12,000 feet/4,000 meters. Up through the last century it was the predominant bread grain for the poor of northern Europe, and even today the taste for rye persists, especially in Scandinavia and eastern Europe. Poland, Germany, and Russia are the leading producers. In Germany, wheat production exceeded rye for the first time only in 1957.

Rye has unusual carbohydrates and proteins, and as a result produces a distinctive kind of bread. It’s described in the next chapter (p. 545).

Rye Carbohydrates Rye contains a large quantity, up to 7% of its weight, of carbohydrates called pentosans (an old term; the new one is arabinoxylans). These are medium-sized aggregates of sugars that have the very useful property of absorbing large amounts of water and producing a thick, viscous, sticky consistency. Thanks to its pentosans, rye flour absorbs eight times its weight in water, while wheat flour absorbs two. Unlike starch, the pentosans don’t retrograde and harden after being cooked and cooled. So they provide a soft, moist texture that helps gives rye breads a shelf life of weeks. Rye pentosans also help control appetite; the dried carbohydrates in rye crisps swell in the stomach, thus giving the sensation of fullness, and they are slowly and only partly digested.

Oats

The world produces more oats than rye today, but 95% of the crop is fed to animals. Oats are the grains of Avena sativa, a grass that probably originated in south-west Asia and gradually came under cultivation as a companion of wheat and barley. In Greek and Roman times it was considered a weed or a diseased form of wheat. By 1600 it had become an important crop in northern Europe, in whose wet climate it does best; oats require more moisture than any other cereal but rice. Other countries, however, continued to disdain it. Samuel Johnson’s Dictionary (London, 1755) gives this definition for oats: “A grain, which in England is generally given to horses, but in Scotland supports the people.”

Today the United Kingdom and the United States are the largest consumers of food oats. U.S. consumption was boosted in the late 19th century by Ferdinand Schumacher, a German immigrant who developed quick-cooking rolled oats for breakfast, and Henry Crowell, who was the first to turn a cereal from a commodity into a retail brand by packaging oats neatly with cooking instructions, labeling it “Pure,” and naming it “Quaker Oats.” Oats are now a mainstay in ready-to-eat granolas, mueslis, and manufactured breakfast cereals.

There are several reasons for the relatively minor status of oats. Like barley, oats have no gluten-producing proteins, which means that they can’t be made into light raised breads. The kernel has adherent husks that make it difficult to process. Oats contain from two to five times the fat that wheat does, mainly in the bran and endosperm rather than the germ, and also carry large amounts of a fat-digesting enzyme. The combination means that oats have a tendency to become rancid. They require a heat treatment that inactivates the enzyme in order to prevent rapid deterioration during storage.

On the other hand, oats do have several virtues. They’re rich in indigestible carbohydrates called beta-glucans, which absorb and hold water, give hot oatmeal its smooth, thick consistency, have a tenderizing, moistening effect in baked goods, and help lower our blood cholesterol levels. The glucans are found mainly in the outer layers of the endosperm under the aleurone layer, and so are especially concentrated in oat bran. Oats also contain a number of phenolic compounds that have antioxidant activity.

Oat Processing Oats are generally used as whole grains, also called groats, because they’re much softer than wheat or corn and don’t break cleanly into endosperm, germ, and bran. The first stage in their processing is a low-temperature “roasting,” which gives the grain much of its characteristic flavor and inactivates the fat-splitting enzyme. (This step also denatures the storage proteins and makes them less soluble, giving the grain greater integrity during cooking.) The whole groats are then processed into various shapes, all of which have the same nutritional value. Steel-cut oats are simply whole groats cut into two to four pieces for faster cooking. Rolled oats are whole kernels that are steamed to make them soft and malleable, then pressed between rollers to make them thin and quick to reabsorb water during cooking or simple soaking (as for muesli). The thinner the oats are rolled, the faster they rehydrate: regular oats are about 0.8 mm thick, “quick-cooking” oats are around 0.4 mm, and “instant” even thinner.

Rice

Rice is the principal food for about half of the world’s population, and in such countries as Bangladesh and Cambodia provides nearly three-quarters of the daily energy intake. Oryza sativa is a native of the tropical and semitropical Indian subcontinent, northern Indochina, and southern China, and was probably domesticated in several places independently, the short-grain types around 7000 BCE in the Yangtze River valley of south-central China, and long-grain types in Southeast Asia somewhat later. A sister species with a distinctive flavor and red bran, Oryza glaberrima, has been grown in west Africa for at least 1,500 years.

Rice found its way from Asia to Europe via Persia, where the Arabs learned to grow and cook it. The Moors first grew large quantities in Spain in the 8th century, then somewhat later in Sicily. The valley of the Po River and the Lombardy plain in northern Italy, the home of risotto, first produced rice in the 15th century. The Spanish and Portuguese introduced rice throughout the Americas in the 16th and 17th centuries. South Carolina was the location of the first commercial American planting in 1685, where the rice-growing expertise of African slaves was important; today most U.S. rice comes from Arkansas and the lower Mississippi region, Texas, and California.

Kinds of Rice There are thought to be more than 100,000 distinct varieties of rice throughout the world. They all fall into one of two traditionally recognized subspecies of Oryza sativa. Indica rices are generally grown in lowland tropics and subtropics, accumulate a large amount of amylose starch, and produce a long, firm grain. Japonica rices, with upland varieties that do well both in the tropics (Indonesian and Filipino types sometimes known as javanicas) and in temperate climates (Japan, Korea, Italy, and California), accumulate substantially less amylose starch than the indicas, and produce a shorter, stickier grain. There are also varieties that are intermediate between indica and japonica. Generally, the higher the amylose content in a rice variety, the more organized and stable the starch granules, and so the more water, heat, and time it takes to cook the grains.

Most rice is milled to remove the bran and most of the germ, and then “polished” with fine wire brushes to grind away the aleurone layer and its oil and enzymes. The result is a very stable refined grain that keeps well for months.

Common categories of rice include the following:

• Long-grain rice has an elongated shape, its length four to five times its width. Thanks to its relatively high proportion of amylose (22%), it tends to require the largest proportion of water to rice (1.7 to 1 by weight, 1.4 to 1 by volume), and to produce separate springy grains that become firm as they cool, and distinctly hard if chilled. Most Chinese and Indian rices are long-grain indicas, as is most of the rice sold in the United States.
• Medium-grain rice is two to three times longer than it is wide, contains less amylose (15–17%) than long-grain rice and requires less water, and develops tender grains that cling to each other. Italian risotto rices and Spanish paella rices are medium-grain japonicas.
• Short-grain rice is only slightly longer than it is wide, and otherwise similar to medium-grain rice. Short-and medium-grain japonicas are the preferred types in north China, Japan, and Korea. They’re ideal for sushi because they cling together in small masses and remain tender even when served at room temperature.
• Sticky rice, also called waxy, glutinous, or sweet rice, is a short-grain type whose starch is practically all amylopectin. It requires the least water (1 to 1 by weight, 0.8 to 1 by volume) and becomes very clingy and readily disintegrates when cooked (it’s often soaked and then steamed, not boiled). Despite its names, it contains no gluten and isn’t sweet, though it’s often used to make sweet dishes in Asia. It’s the standard rice in Laos and northern Thailand.
• Aromatic rices are a distinctive group of mainly long-and medium-grain varieties that accumulate unusually high concentrations of volatile compounds. Indian and Pakistani basmati (Urdu for “fragrant,” accent on the first syllable), Thai jasmine (an unusual long-grain but low-amylose type), and U.S. Della are well-known aromatic rices.
• Pigmented rices have bran layers that are rich in anthocyanin pigments. Red and purple-black colors are the most common. The bran may be left intact, or partly milled away so that only traces of color are left.

Brown Rice Brown rice is unmilled, its bran, germ, and aleurone layers intact. Any kind of rice, whether long-grain, short-grain, or aromatic, may be sold in its brown form. It takes two to three times longer to cook than the milled version of the same variety, and has a chewy texture and a rich aroma, often described as nutty. Thanks to the oil in its bran and germ, it’s more susceptible to staling than polished rice, and is best stored in the refrigerator.

Parboiled or Converted Rice For more than 2,000 years, rice producers in India and Pakistan have parboiled nonaromatic varieties before they remove the hull and mill them to white rice. They steep the freshly harvested grain in water, boil or steam it, and then dry it again before hulling and milling. This precooking brings several advantages. It improves the nutritional quality of the milled grain by causing vitamins in the bran and germ to diffuse into the endosperm, and causing the aleurone layer to adhere to the grain. Precooking the starch also hardens the grain and makes its surface less sticky, so when cooked again, parboiled rice produces separate firm intact grains. Parboiled rice also has a distinctive nutty flavor; the soaking activates enzymes that generate sugars and amino acids that then participate in browning reactions during drying; and partial breakdown of lignin in the attached hull provides vanillin and related compounds. Parboiled rice takes longer to cook than ordinary white rice, a third to half again the time, and its texture is so firm that it can seem coarse.

Different forms of rice. Brown rice includes the outer fruit and seed coats that make up the bran, and the embryo and oil-and enzyme-rich aleurone layer. Polished rice is the central mass of endosperm cells, freed from all other parts of the grain; it’s mainly starch and protein. Wild rice is the whole grain of a North American grass; it is heated to dry it out and develop flavor, and this processing gives its endosperm a distinctive glassy appearance.

Quick-Cooking Rice Quick-cooking rice is manufactured by cooking white, brown, or parboiled rice, thus disrupting its cell walls and gelating its starch, then fissuring the grain in order to speed the infiltration of hot water when the consumer cooks it, and finally drying it. The fissuring may be accomplished with dry heat, rolling, microwave treatments, or freeze-drying.

Rice Flavor The flavor of rice depends on the variety and the degree to which it is milled. The outer portions of the rice grain contain more free amino acids, sugars, and minerals, and proportionally less starch. The more a rice kernel is milled, and so the more of its surface is removed, the less flavor and the higher proportion of starch it contains.

The aroma of standard white rices has green, mushroomy, cucumber-like, and “fatty” components (from 6, 8, 9, and 10-carbon aldehydes), as well as a slight popcorn note and floral, corn-like, hay-like, and animal qualities. Brown rices contain these and also small amounts of vanillin and maple-sugar-like sotolon. Aromatic rices are especially rich in the popcorn-like aromatic component (acetylpyrroline), which is also an important element in screwpine leaves (p. 411), and cooked popcorn and bread crust. Because it is volatile and not regenerated during cooking, the popcorn aromatic escapes during cooking, and its concentration declines. This is one reason for pre-soaking aromatic rices; this step shortens the cooking and minimizes aroma loss.

Cooking with Rice

Many Traditional Methods The cooking of rice is a matter of introducing moisture throughout the grains and heating them enough to gelate and soften the starch granules. Indian cooks boil the rice in an excess of water that’s poured off when the rice is done, so the grains end up intact and separate. Chinese and Japanese cooks boil rice with just enough water to moisten and cook it through in a closed pot, which produces a mass of grains that cling together and are easily eaten with chopsticks. Where rice has always been an everyday staff of life, through much of East Asia, it’s usually prepared simply in water, and judged by the intactness of its grains and their whiteness, gloss, tenderness, and flavor. Where rice was more unusual and even a luxury, in central Asia, the Middle East, and the Mediterranean, it’s often enriched with broths, oils, butter, and other ingredients to make such dishes as pilafs, risottos, and paellas. Iranians, perhaps the most sophisticated rice cooks, make polo by partly boiling long-grain rice in excess water, layering it with a variety of cooked meats, vegetables, dried fruits, and nuts, then gently steaming to finish the cooking, and managing the heat so that a brown crust of rice, the prized tahdig, forms at the bottom.

Rinsing and Soaking An initial rinsing of the dry rice removes surface starch and thus a source of added stickiness. Some rices, notably basmatis and Japanese varieties, are either soaked in water or allowed to rest for 20–30 minutes after washing; they thus absorb some water, which will speed the subsequent cooking. Brown and wild rices can be treated similarly.

After Cooking: Resting, Reheating Once cooked, rice benefits from a resting period to allow the grains to cool down somewhat and become firmer, so that they aren’t as easily broken when scooped from the pot and served. Leftover rice is often hard due to the retrogradation of the starch, which is cured by heating it up to the gelation temperature again. Rice is easily softened by reheating to 160ºF/70ºC or above, either with a little added water in a pot or in the microwave oven, or fried to make fried rice, rice cakes, or croquettes.

Keeping Rice Safe Cooked rice turns out to be a potential source of food poisoning. Raw rice almost always carries dormant spores of the bacterium Bacillus cereus, which produces powerful gastrointestinal toxins. The spores can tolerate high temperatures, and some survive cooking. If cooked rice is left for a few hours at room temperature, the spores germinate, bacteria multiply, and toxins accumulate. Ordinary cooked rice should therefore be served promptly, and leftovers refrigerated to prevent bacterial growth. The rice in Japanese sushi is served at room temperature, but the surface of its cooked grains are coated with a flavorful and antimicrobial mixture of rice vinegar and sugar. Rice salads should be similarly acidified with vinegar, lemon or lime juice.

Some Other Rice Preparations and Products Cultures across the world have found many different inventive uses for rice. Here is a brief sampling.

Rice Flour Rice flour is notable for being around 90% starch, and for having the smallest starch granules of the major cereals, a half to a quarter the size of wheat starch granules. When used to thicken sauces or fillings, it provides an especially fine texture. And thanks to its low protein content, the dry flour absorbs relatively little water. This means that when it’s used to make a frying batter for Japanese tempura, rice flour gives a thin consistency with relatively little water, and so the batter readily fries to a crisp, dry texture.

Because rice flour contains no elastic gluten proteins, it can’t be used to make raised breads. But the same lack of gluten makes rice flour a useful ingredient for people with gluten intolerance. Bakers make a reasonable approximation of raised bread by supplementing rice flour with xanthan or guar gum or other long-chain carbohydrates, which help bind the dough together and retain the gas bubbles produced by yeasts or chemical leavenings.

Rice Powder Rice powder is a condiment made in Vietnam and Thailand by roasting the grains, then grinding them; it’s sprinkled on a variety of dishes just before eating.

Rice Noodles and Rice Paper Despite rice’s lack of gluten, noodles and thin sheets can be made from rice-flour doughs (p. 579). Rice paper is used as a wrapper to enclose meat and vegetable preparations, and can be eaten either simply moistened or fried.

Mochi Mochi is the Japanese name for a chewy, almost elastic preparation of sticky rice that may be formed into balls or into thin sheets for wrapping around a filling of some kind. It’s made by steaming sticky rice, then pounding it to a paste, or by making a dough from sticky rice flour and kneading it for 30 minutes. The pounding or kneading organizes the bushy amylopectin starch molecules into an intermeshed mass that resists changes in its structure.

Lao Chao Lao chao is a Chinese fermented rice made from sticky rice. The rice is steamed, cooled, made into small cakes with a starter that includes the mold Aspergillus oryzae (p. 755) and yeasts, and held at room temperature for two to three days until it becomes soft, sweet, and tart, with a fruity and alcoholic aroma.

Wild Rice Wild rice is not a species of the true tropical rice genus Oryza. It’s a distant relative, a cool-climate water grass that produces unusually long grains, to three-quarters of an inch (2 cm), with a dark seedcoat and a complex, distinctive flavor. Zizania palustris is a native of the upper midwestern Great Lakes region of North America, where it grows in shallow lakes and marshes and was gathered in canoes by the Ojibway and other native peoples. It’s the only cereal from North America to have become important as a human food. Wild rice is unusual among the cereals for containing double the usual amount of moisture at maturity, around 40% of the kernel weight. It thus requires more elaborate processing than true rice in order to be stored. It’s first matured in moist piles for a week or two, during which immature grains continue to ripen and microbes grow on the grain surfaces, generating flavor and weakening the husks. Then it is parched over a fire to dry the grain, flavor it, and make the husk brittle; and finally it’s threshed to remove the husk.

Texture and Flavor Wild rice has a firm, chewy texture thanks to its intact bran layer and the parching process, which gelates and then anneals the starch much as parboiling does for true rice. It takes longer to cook than most grains, sometimes an hour or more, because its starch has been precooked into a hard, glassy mass, and because its bran layers are impregnated with cutins and waxes (p. 262) to resist the absorption of water (in nature, the grains fall into the water and lie dormant for months or even years before germinating). The dark pigmentation may also contribute; it is partly green-black chlorophyll derivatives and partly black phenolic complexes generated by browning enzymes. Producers often slightly abrade the grains to improve their water absorption and shorten cooking time. Cooks can also pre-soak the grains for hours in warm water.

The flavor of the raw grain has earthy and green, flowery, tea-like notes. Curing amplifies the tea notes (from pyridines) but may add an undesirable mustiness; parching generates browning reactions and a toasted, nutty character (from pyrazines). Different producers use different methods for curing (none, brief, extended) and parching (low or high temperatures, open fires or indirectly heated metal drums), so the flavor of wild rice varies greatly.

Domesticated Wild Rice Relatively little wild rice is still gathered from uncultivated, naturally occurring stands. Today most is grown in artificially flooded paddies, and harvested mechanically after the fields are drained. Cultivated wild rice therefore has more consistently mature, dark seedcoats than the gathered grain. To taste truly wild rice from its native region and savor the differences among small producers, it’s necessary to read labels carefully.

Maize, or Corn

Maize, known in the United States as “corn” and among biologists as Zea mays, was domesticated in Mexico some 7,000 to 10,000 years ago from a large grass called teosinte (Zea mexicana), which grows in open woodlands. Unlike the Old World cereals and the legumes, which human selection altered in relatively minor ways, corn is the result of several drastic changes in the structure of teosinte that concentrated pollen production at the top of the plant and female flower production — and cob and kernel production — along the main stalk. The large size of both plant and fruit made corn agriculture relatively easy, and corn quickly became the basic food plant of many other early American cultures. The Incas of Peru, the Mayas and Aztecs of Mexico, the cliff dwellers of the American Southwest, Mississippi mound builders, and many seminomadic cultures in North and South America depended on corn as a dietary staple. Columbus brought corn back with him to Europe, and within a generation it was being grown throughout southern Europe.

Corn is now the third largest human food crop in the world after wheat and rice, and is the primary nourishment for millions of people in Latin America, Asia, and Africa. In Europe and the United States, where more corn is fed to livestock than to people, it’s appreciated for its unique flavor, for the texture and substance it contributes to a variety of boiled, baked and fried foods, and as a snack food. Corn also provides mash for making whiskey, corn starch for thickening sauces and fillings, corn syrup for flavoring and lending viscosity to various sweet preparations, and corn oil. Different parts of the plant are also turned into many industrial products.

Kinds and Colors of Corn There are five general kinds of corn, each characterized by a different endosperm composition. It appears that a high-protein popcorn type was the first corn to be cultivated, but all five were known to native Americans long before the coming of Europeans.

• Popcorn and flint corn have a relatively large amount of storage protein that surrounds granules of high-amy-lose starch.
• Dent corn, the variety most commonly grown for animal feed and for milled food ingredients (grits, meals, flours), has a localized deposit of low-amylose, “waxy” starch at the crown of the kernel, which produces a depression, or dent, in the dried kernel.
• Flour corns, including the standard varieties of blue corn, are soft and easily ground because their endosperm is a discontinuous and weak combination of relatively little protein, mostly waxy starch, and air pockets. What we call Indian corn today are flour and flint varieties with variegated kernels.
• Sweet corn, a popular vegetable in the United States when immature, stores more sugar than starch, and therefore has translucent kernels and loose, wrinkled skins (starch grains reflect light and plump out the kernels in the other types). Most corn-producing countries also eat immature corn, but use the other general-purpose corn types. The native Americans who first developed it apparently enjoyed sweet corn for its full flavor when parched.

The different kinds of corn also come in various colors, some of which were originally selected by native Americans for ceremonial use. The interior is usually either unpigmented and white, or yellow with nutritionally valuable fat-soluble carotenes and xanthophylls (beta carotene, lutein, zeaxanthin). Blue, purple, and red kernels carry water-soluble anthocyanins in their aleurone layer, the nutrient-rich cell layer just under the hull.

Alkaline Treatment: Several Benefits Corn is unusual among the grains for its large size, and for the thickness and toughness of its outer pericarp, or hull. Early corn eaters developed a special pretreatment to ease the removal of the hull, which is called nixtamalization (from an Aztec word): they cooked the kernels in water made alkaline with a variety of substances. The Mayas and Aztecs used ashes or lime; North American tribes, ashes and naturally occurring sodium carbonate deposits; and a contemporary Mayan group burns mussel shells for the same purpose. One of the major glue-like components of plant cells walls, hemicellulose, is especially soluble in alkaline conditions. Nixtamalization softens the hull and partly detaches it from the rest of the kernel so that it can be rubbed off and washed away. It also helps transform the kernels into a cohesive dough for making tortillas and other preparations (see below), and it releases much of their bound niacin so that we can absorb and benefit from it.

Corn Flavor Corn has a distinctive flavor unlike that of any other grain. Popcorn and other dry corn products toasted at a high temperature develop a number of characteristic carbon-ring compounds, including one that they share with basmati rice (acetylpyrroline). Alkaline processing gives rise to yet another set of distinctive aroma molecules, including one that is a breakdown product of the amino acid tryptophan, and a close chemical and aromatic relative of a characteristic note in concord grapes and wood strawberries (aminoacetophenone, related to the fruits’ methyl anthranilate). Masa can also have violet-like and spicy notes (from ionone and vinylguaiacol).

Types of corn. Left to right: Kernels of pop, dent, and sweet corn. Its abundant hard endosperm helps popcorn contain the steam pressure that eventually explodes it.

Whole-grain Corns: Hominy, Corn Nuts Common corn ingredients and foods can be divided into two general groups: those based on the whole grain, and those based on ground grain. There’s also a basic division between dry, untreated materials and “wet-processed” alkaline-treated materials.

Whole-grain versions of corn are relatively few, with popcorn by far the most common. Hominy consists of whole corn kernels, preferably white, cooked for 20–40 minutes in a solution of lime or lye, then washed of their hulls and excess alkaline solution. Hominy is used in soups (pozole), stews, and side dishes, and has a dense, chewy consistency. Corn Nuts are a familiar snack food made from the largest kernels known, the Cuzco gigante variety from Peru. The kernels are treated with alkali to remove the hulls, soaked for some hours in warm water, fried to develop color, flavor, and a crunchy texture, then flavored.

Popcorn It appears from archaeological remains in Mexico that popping in the embers of a fire may have been the first method for cooking corn. Early explorers described popped corn among the Aztecs, Incas, and North American tribes. In the 19th century, Americans served popcorn as a breakfast cereal, made it into porridges, puddings, and cakes, added it to soups, salads, and main dishes, and mixed it with molasses to make an ancestor of the sweet popcorn ball and Cracker Jack. Popcorn was a popular finger food in the United States in the 1880s, then became associated with movie theatres, and later with watching television in the home. In the 21st century, most of the popcorn sold in supermarkets is packaged for microwave cooking.

How Popcorn Pops Some flint and dent varieties of corn will explode and form a crisp puff, but expand far less than true popping varieties, which are generally smaller and contain a greater proportion of hard translucent endosperm. Thanks to a denser arrangement of cellulose fibers, the popcorn hull (pericarp) conducts heat several times faster than the hull of ordinary corn; and thanks to both its density and greater thickness, it is several times stronger: so the hull transmits heat more rapidly to the endosperm, and can withstand higher steam pressure from within before giving way.

As the temperature inside the corn kernel reaches and passes the boiling point, the protein matrix and starch granules soften, and moisture in the granules turns into steam. The steam softens the starch even more, and the many thousands of little steam pockets exert a growing pressure against the hull. The softening of starch and protein continues until the internal pressure approaches seven times the external pressure of the atmosphere, at which point the hull breaks open. The sudden pressure drop inside the kernel causes the pockets of steam to expand, and with them expands the soft protein-starch mixture, which puffs up and then stiffens as it cools off, becoming light and crisp. (If the popping is done in a tightly covered pan that offers no escape for the water vapor, the endosperm will retain it and be tough and chewy; the pan lid should be left slightly ajar.)

Popcorn pops best at a temperature around 380ºF/190ºC, and can be popped in hot oil, in hot air poppers, and in the microwave oven. Different hybrids pop best with different methods. Microwave popcorn bags develop the necessary high temperatures by means of a thin layer of microwave-reflecting mylar.

Dry-milled Corn Foods: Grits, Cornmeal, Corn Flour Most corn is prepared and eaten in ground form, and dry-milled products are ground directly from the stored grain, usually yellow dent corn, without any pretreatment. These days they’re generally refined to exclude the hull and germ, an innovation that dates from around 1900 and that made large-scale milling practical. The rarer whole-grain corn meal and flour, sometimes ground between stone wheels, are richer in fiber, flavor, and nutrients, but also stale rapidly thanks to the oils and related substances in the germ, which become oxidized on contact with air.

Grits are relatively coarse corn endosperm particles between 0.6 and 1.2 mm across. They’re used to manufacture breakfast cereals, snacks, and beer, and are cooked into a kind of porridge that’s especially beloved in the American South. Grits were once made from alkaline-treated hominy, but this is now rare.

Cornmeal is finer than grits, with particles down to 0.2 mm across, absorbs water and cooks faster than grits, and provides a subtler graininess. It’s used to make unleavened mush, polenta, and johnnycakes as well as corn breads, muffins, and other baked and fried foods that include some wheat flour and leavening for lightness.

Corn flour is the finest-ground form of corn, with particles smaller than 0.2 mm, and is usually mixed with other ingredients to provide flavor in various baked and fried foods.

Wet-milled Corn: Masa, Tortillas, Tamales, Chips Tortillas, tamales, and corn chips are made from corn grains that are milled when wet, after they have undergone the preliminary cooking step called nixtamalization (p. 478). The corn is first cooked in a solution (0.8–5%) of calcium hydroxide, or lime, for a few minutes to an hour, then is left to steep and slowly cool for 8 to 16 hours. During the steeping, the alkalinity softens the hull and cell walls throughout, causes the storage proteins to bond to each other, and breaks apart some of the corn oil into excellent emulsifiers (monoand diglycerides). After steeping, the soaking solution and softened hulls are washed away, and the kernels, including the germ, are then stone ground to produce the dough-like material called masa. Stone grinding cuts the kernels, mashes them, and kneads the mass, mixing together starch, protein, oils, emulsifiers, and cell wall materials, and the lime’s molecule-bridging calcium. With further kneading, this combination develops into a cohesive, plastic dough.

The convenience form of masa is masa harina, a flour made by flash-drying freshly made masa into small particles. Because it’s made with less water than normal masa and then is dried, masa harina has less masa aroma and an added browned, toasty aroma, and produces a softer texture than fresh masa.

Tortillas, Tamales, and Corn Chips Tortillas are made by forming finely ground masa into thin sheets, then quickly cooking them, traditionally on a hot pan for a minute or two, now in continuous commercial ovens for 20–40 seconds. Tamales are small cakes of masa that enclose a filling, and are traditionally formed in the papery husks of corn ears and steamed. The dough is moistened with a broth and enriched, flavored, and aerated by beating it thoroughly with lard. The lard is semisolid at room temperature and helps lubricate the masa materials and trap air bubbles in a fluffy mass that expands during steaming. And fried chips are made both from tortillas and directly from masa. Tortilla chips are made by deep-frying tortillas, while corn chips are made by forming strips of lower-moisture, coarse masa and then deep-frying them.

Minor Cereals

The following cereals are only occasionally encountered in Europe and the United States, though some are very important in the dry tropics and subtropics.

Fonio Fonio and black fonio are African grasses distantly related to maize and sorghum. Digitaria exilis and D. iburua were domesticated on the West African savanna around 5000 BCE, and are typical cereals in most respects. The tiny grains are made into porridge and couscous, popped, brewed into beer, and mixed with wheat to make breads.

Millet Millet is the name used for a number of different grains, all of them with very small round seeds, 1–2 mm in diameter (species of Panicum, Setaria, Pennisetum, Eleusine). The millets are native to Africa and Asia, and have been cultivated for 6,000 years. They’re especially important in arid lands because they have one of the lowest water requirements of any cereal, and will grow in poor soils. The grains are remarkable for their high protein content, from 16 to 22%, and are popped and also made into porridge, breads, malts, and beers.

Sorghum Sorghum (Sorghum bicolor) evolved in the steppes and savannas of central and south Africa, was domesticated there around 2000 BCE, and soon after was taken to India and then to China. Thanks to their tolerance of drought and heat, sorghums have become established in most warm countries with marginal croplands. The fruits are small, around 4 mm long and 2 mm wide, and are boiled like rice, popped, and used in many different variations on porridges, flatbreads, couscous, and beers. Sorghum shouldn’t be sprouted; as the seed germinates, it produces a protective cyanide-generating system (p. 258).

Teff Teff, Eragrostis tef, is the major crop in Ethiopia, but rarely grown elsewhere. Its tiny (1 mm) seeds come in a variety of colors, from dark to red and brown to white, with the pigmented varieties said to have more flavor. Teff is most often made into the spongy flatbread called injera, which unlike most breads stays soft and chewy for several days.

Triticale Triticale is a modern, artificial cross between wheat and rye (Triticum x Secale), first documented late in the 19th century and grown commercially around1970. There are many different forms, the most commonly grown a cross between durum wheat and rye. Its grains are generally more similar to wheat than to rye, though the breadmaking qualities of most varieties aren’t as good as wheat’s. Triticale is now mostly grown for animal feed, and is sometimes sold in health food stores.

Pseudocereals

Amaranth, buckwheat, and quinoa are not members of the grass family and so are not true cereals, but their seeds resemble the cereal grains and are used in similar ways.

Amaranth Amaranth is the tiny seed, just 1–2 mm across, of three species of Amaranthus that originated in Mexico and Central and South America, and were cultivated more than 5,000 years ago. (There are also species of amaranth native to the Old World, but they are used exclusively as green vegetables.) Today amaranth supplements other grains in many baked goods, breakfast cereals, and snacks. The Aztec combination of popped seeds and sticky sweetener lives on in the Mexican alegria (“joy”) and Indian laddoo. Amaranth seeds contain substantially more protein and oil than the cereals.

Buckwheat Buckwheat, Fagopyrum esculentum, is a plant in the Polygonum family, a relative of rhubarb and sorrel. It’s a native of central Asia, was domesticated in China or India relatively recently, around 1,000 years ago, and was brought to northern Europe during the Middle Ages. It tolerates poor growing conditions and matures in a little over two months, so it has long been valued in cold regions with short growing seasons.

Buckwheat kernels are triangular, a sixth to a third of an inch/4–9 mm across, with a dark hull (pericarp). The inner seed is a mass of starchy endosperm surrounding a small embryo and contained in a light green-yellow seed coat. Intact seeds with the hull removed are called groats. Buckwheat is about 80% starch and 14% protein, mostly salt-soluble globulins. It contains about double the oil of most cereals, and this limits the shelf life of groats and flour. The hulled groats are about 0.7% phenolic compounds, some of which give the grain its characteristic astringency. The distinctive aroma of cooked buckwheat has nutty, smoky, green, and slightly fishy notes (due respectively to pyrazines, salicylaldehyde, aldehydes, and pyridines).

Buckwheat flour contains a small amount of mucilage, a complex carbohydrate a bit like amylopectin — it’s made up of about 1,500 sugar molecules bonded together into a branched structure. Though a minor component in the flour, the mucilage absorbs water and may provide some of the stickiness that barely holds an all-buckwheat noodle together (p. 577).

Buckwheat is a staple food in parts of China, Korea, and Nepal. In the Himalayan region, buckwheat is used to make chillare, a flatbread, as well as fritter-like pakoras and sweets. In northern Italy, it’s mixed with wheat to make flat noodles called pizzoccheri, and mixed with corn meal in polenta. In Russia it’s used to make the small pancakes called blini; and whole groats are toasted to make the nutty-tasting porridge kasha. In Brittany it produces distinctive crêpes. The Japanese make soba, buckwheat noodles. In the United States it’s most often encountered in pancakes, to which it contributes tenderness and a nutty aroma.

Quinoa Quinoa is a native of northern South America, was domesticated near Lake Titicaca in the Andes around 5000 BCE, and was a staple food of the Incas, second in importance only to the potato. Chenopodium quinoa is in the same family as beets and spinach. The grains are small yellow spheres between 1 and 3 mm across. The outer pericarp of many quinoa varieties contains bitter defensive compounds called saponins, which can be removed by brief washing and rubbing in cold water (prolonged soaking deposits saponins within the seed). Quinoa can be cooked like rice or added to soups and other liquid dishes; it’s also popped, and is ground and made into a variety of flatbreads.

Legumes:
Beans and Peas

Beans and peas belong to the third largest family among the flowering plants (after the orchid and daisy families), and the second most important family in the human diet, after the grasses. The distinctive contribution of the legumes is their high content of protein, two to three times that of wheat and rice, which they develop thanks to their symbiosis with certain soil bacteria. Species of Rhizobium bacteria invade the roots of legume plants and convert abundant nitrogen in the air into a form that the plant can use directly to make amino acids and thus proteins. Legumes have long been an essential alternative to protein-rich but more costly animal foods, and are especially prominent in the foods of Asia, Central and South America, and the Mediterranean. A remarkable sign of their status in the ancient world is the fact that each of the four major legumes known to Rome lent its name to a prominent Roman family: Fabius comes from the fava bean, Lentulus from the lentil, Piso from the pea, and Cicero — most distinguished of them all — from the chick pea. No other food group has been so honored!

There are about 20 different species of legume cultivated on a large scale (see box, p. 484). The oil crops, soybean and peanut, far outdistance the legumes eaten more or less whole; the oils are used industrially as well as in the kitchen, and soybeans are a major livestock feed in the United States.

Legume Structure and Composition

Legume seeds consist of an embryonic plant surrounded by a protective seed coat. The embryo in turn is made up of two large storage leaves, the cotyledons, together with a tiny stem. The cotyledons provide the bulk of the nourishment, as the endosperm does in the grains. In fact, the cotyledons are actually a transformed endosperm. When pollen joins ovule in the process of fertilization, both an embryo and a primitive nutritional tissue, the endosperm, are formed. In the grains, the endosperm develops along with the embryo and remains the storage organ of the mature fruit. But in the legumes, the endosperm is absorbed by the embryo, which repackages the nutrients in its cotyledons.

Some Common Beans and Peas

Common Name

Scientific Name

Natives of Europe and Southwest Asia

Chickpea, garbanzo, bengal gram

Cicer arietinum

Lentil, masoor dal

Lens culinaris

Pea

Pisum sativum

Fava bean, broad bean

Vicia faba

Lupine

Lupinus species

Alfalfa

Medicago sativa

Natives of India and East Asia

Soybean

Glycine max

Mung bean, green/golden gram

Vigna radiata

Black gram, urad dal

Vigna mungo

Azuki bean

Vigna acutifolia

Rice bean

Vigna umbellata

Moth bean

Vigna aconitifolia

Pigeon pea, red gram

Cajanus cajan

Lathyrus, vetch, khesari dal

Lathyrus sativus

Hyacinth bean

Lablab purpureus

Winged bean

Psophocarpus tetragonolobus

Natives of Africa

Black-eyed pea, cowpea, crowder

Vigna unguiculata

Bambara groundnut

Vigna subterranea

Natives of Central and South America

Bean, common bean, haricot, etc.

Phaseolus vulgaris

Lima bean, butter bean

Phaseolus lunatus

Tepary bean

Phaseolus acutifolius

Runner bean

Phaseolus coccineus

Peanut

Arachis hypogaea

The seed coat is interrupted only at the hilum, the small depression where the seed has been attached to the pod, and where it will absorb water once it’s in the ground or the pot. The seed coat may be fairly thin, as in the peanut, but is as much as 15% by weight of the chickpea and 30% of the lupin. The legume seed coat is almost entirely cell-wall carbohydrates, and includes most of the seed’s indigestible fiber. The coats of colorful varieties — pinks, reds, black — are rich in anthocyanin pigments and related phenolic compounds, and therefore in antioxidant power.

Most beans and peas are mainly protein and starch (see box, p. 489). The major exceptions are soybeans and peanuts, which are around 25% and 50% oil respectively. Many legumes are several percent sucrose by weight, and noticeably sweet.

Some legume seeds are rich in defensive secondary compounds (p. 258), notably protease inhibitors, lectins, and in the case of tropical lima beans, cyanide-generating compounds (American and European lima varieties generate little or no cyanide). Animals fed a diet of raw beans will actually lose weight. All of these potentially toxic compounds are disabled or removed by cooking.

Seed Colors The colors of beans and peas are determined mainly by anthocyanin pigments in the seed coat. Solid reds and blacks generally survive cooking, while mottled patterns become washed out when the water-soluble pigments leak into adjacent nonpigmented areas and into the cooking water. The intensity of color is best maintained by minimizing the amount of cooking water; start the beans in just enough water to cover, and add water only as needed to keep them barely covered. Persistently green peas and dried beans owe their color to chlorophyll.

Pale beans with translucent seed coats sometimes develop a delicate pink color in the small embryonic stem when they’re cooked. This is probably a result of the same reaction that causes the reddening of poached quinces and pears (p. 281).

Legumes and Health:
The Intriguing Soybean

Beans and peas are generally excellent sources of a number of nutrients, including protein, iron, various B vitamins, folic acid, and starch or oil. Varieties with colored seed coats provide valuable antioxidants. Among all the legumes, however, soybeans appear to have unusual potential for affecting human health. Epidemiological studies have shown that countries in which soybeans are a staple food, notably China and Japan, have significantly lower rates of heart disease and cancer. It may be that soybeans are part of the explanation.

The anatomy of a legume seed. A side view with one of the two cotyledons removed to show the embryo. The hilum is a small pore through which water can pass directly to the embryo; it and the seed coat control the rate at which dry beans and peas absorb water and soften during cooking.

It turns out that soybeans contain storage forms of several phenolic compounds called isoflavones, which are liberated by the action of our intestinal bacteria as active compounds (genistein, daidzein, and glycitein) that resemble the human hormone estrogen. The active forms are therefore referred to as “phytoestrogens” (from the Greek phyton, “leaf”). Mung beans and other legumes also contain isoflavones, but in much smaller quantities. (Of commonly eaten soy foods, the boiled whole beans contain by far the greatest concentration of isoflavones, about double the amount found in tofu.) Phytoestrogens do appear to have hormone-like and other effects on the human body. There’s evidence that they may slow bone loss and the development of prostate cancer and heart disease. However, some studies suggest that phytoestrogens can worsen preexisting breast cancer, and are protective against some cancers only when consumed during adolescence. Our understanding of phytoestrogens is still very incomplete. It’s too early to say whether soybeans are more beneficial to human health than any other seed, or whether it’s a good idea to eat them often.

Saponins are soap-like defensive compounds that have a water-soluble end and a fat-soluble end, so they can act as emulsifiers and foam stabilizers. They’re one of the reasons that a pot of soybeans boils over so readily! Soybeans are a rich source of saponins, which may make up 5% of their total weight, about half of which is in the hulls. Some plant saponins are so strong that they damage our cell membranes. Soy saponins are gentler, and bind to cholesterol so that the body can’t absorb it efficiently. Soybeans are also a good source of phytosterols, chemical relatives of cholesterol that also interfere with our absorption of cholesterol and thus lower blood cholesterol levels.

The Problem of Legumes
and Flatulence

Several chemical constituents of beans are responsible for an uncomfortable, sometimes embarrassing consequence of eating legumes: the generation of gas in the digestive system.

The Cause: Indigestible Carbohydrates Everyone produces a mixture of gases from their intestine, about a quart a day, thanks to the growth and metabolism of our resident bacteria. Many legumes, especially soy, navy, and lima beans, cause a sudden increase in bacterial activity and gas production a few hours after they’re consumed. This is because they contain large amounts of carbohydrates that human digestive enzymes can’t convert into absorbable sugars. These carbohydrates therefore leave the upper intestine unchanged and enter the lower reaches, where our resident bacterial population does the job we are unable to do.

One kind of troublesome carbohydrate is the oligosaccharides, molecules consisting of three, four, and five sugar molecules linked together in an unusual way. But the latest research suggests that the oligosaccharides are not the primary source of gas. The cell-wall cements generate just as much carbon dioxide and hydrogen as the oligosaccharides — and beans generally contain about twice as much of these carbohydrates as they do oligosaccharides.

The Cures: Soaking, Long Cooking A commonly used method for reducing the gassiness of beans is to boil them briefly in excess water, let them stand for an hour, then discard the soaking water and start the cooking with fresh water. This does leach out most of the water-soluble oligosaccharides — but it also leaches out significant quantities of water-soluble vitamins, minerals, simple sugars, and seed-coat pigments: that is, nutrients, flavor, color, and antioxidants. That’s a high price to pay. An alternative is simple prolonged cooking, which helps by eventually breaking down much of the oligosaccharides and cell-wall cements into digestible single sugars. Oligosaccharides are also consumed by the bean during germination, and consumed by microbes during fermentation: so sprouts, miso, and soy sauce, as well as extracts like bean curd, are less offensive than whole beans.

Bean Flavor

Beans owe their typical beany flavor to a large endowment of the enzyme lipoxygenase, which breaks unsaturated fatty acids into small, odorous molecules. The main components of beaniness are grassy hexanal and hexanol and mushroomy octenol. Lipoxygenase gets its chance to act when the bean cells are damaged and there’s enough moisture and oxygen available: for example, when fresh beans are bruised, or dried damaged beans are soaked or brought slowly to a boil. The strong beaniness of soybean products is generally accepted in Asia but objected to in the West, where food scientists have developed techniques to minimize it (see box, p. 494). The aroma of cooked beans also has a distinct sweet note, which comes from lactones, furans, and maltol.

Some beans may be warehoused for years before they find their way to supermarkets or into prepared foods. Prolonged storage causes legumes to lose some typical flavor notes and accumulate stale ones.

Bean Sprouts

Bean sprouts are best known from the cooking of China, where mung bean sprouts became popular in the south and soybean sprouts in the north about 1,000 years ago. Many other legumes are sprouted in Asia and elsewhere, from the tiny alfalfa seed to the massive fava bean. Cooks sometimes trim larger sprouts of their rootlets, primordial leaves, and dense cotyledons, so that the subtle texture and flavor of the stems can be enjoyed without distraction. Sprouts are generally cooked minimally if at all to preserve the delicate flavor and tender but crunchy texture.

Cooking Legumes

Most mature legume seeds are starchy, and require cooking in water to soften the cotyledon cell walls and starch granules. Fresh shell beans are mature but still moist, and so cook fairly quickly, in 10 to 30 minutes. They’re also sweeter than the dried beans. Peas, lima beans, cranberry beans, and soybeans (edamame) are the legumes most commonly eaten fresh.

Whole dried beans and peas can take an hour or two to cook, much longer than the dried grains. This is due in part to their larger size, but also to the effectiveness of their seed coat at controlling the absorption of water, which is necessary for softening the cell walls and starch. Initially water can enter only through the hilum, the little pore on the curved back of the bean. After 30–60 minutes in cool water (more quickly in hot), the seed coat has become fully hydrated and expanded. From this point on, most of the water flowing into the bean passes across the entire seed coat surface, but the rate of flow is still limited. Legumes whose hulls have been removed — split peas, many Indian dals — cook more quickly and disintegrate into a mush.

The Cooking Liquid The quality of cooked beans and the time it takes to cook them depend on the cooking liquid. In vegetable cooking, large volumes of vigorously boiling water minimize enzyme damage to vitamins and pigments by keeping the temperature high when the vegetables are added. Long-cooked legumes are a different story. The greater the volume of cooking water, the more color, flavor, and nutrients are leached out of the beans, and the more they’re diluted. So these seeds are best cooked in just enough water for them to soak up and to cook in. And though boiling temperatures speed cooking, the turbulence of boiling water can damage the seed coats and cause the beans to disintegrate; lower temperatures (180–200ºF/80–93ºC) are slower but gentler.

The cooking water’s content of dissolved substances also affects cooking times and textures. Hard water with high levels of calcium or magnesium actually reinforces the bean cell walls (p. 282). It can therefore slow the softening of the beans or even prevent them from softening fully. Acidic cooking liquids slow the dissolving of cell-wall hemicelluloses and therefore the softening process, while alkaline cooking water has the reverse effect. Finally, many cooks and cookbooks say that adding salt to the cooking water prevents beans from softening. It does slow the rate at which they absorb water, but they do eventually absorb it and soften. And when beans are pre-soaked in salted water, they actually cook much faster (below).

Maintaining the Texture of Cooked Beans Three substances slow the softening of beans and therefore make it possible for the cook to simmer beans for hours or reheat them without disintegrating them. Acids make the cell-wall hemicelluloses more stable and less dissolvable; sugar helps reinforce cell-wall structure and slows the swelling of the starch granules; and calcium cross-links and reinforces cell-wall pectins. So such ingredients as molasses — somewhat acid and rich in both sugar and calcium — and acidic tomatoes can preserve bean structure during long cooking or reheating, as for example in baked beans.

Reducing Cooking Times by Presoaking Though beans are an ideal food for slow, easy cooking in a low oven, it’s sometimes desirable to cook them faster. In mountainous areas, where high altitude lowers the boiling point, the cooking of dry beans can become an all-day affair.

There are several different ways to reduce the cooking time of beans and peas. The simplest way is to soak dried beans in water before cooking them. This reduces cooking time by 25% or more, and for a very basic reason: heat penetrates a dry seed faster than water does. If beans are cooked directly from the dry state, much of the cooking time is actually spent waiting for water to get to the center. Meanwhile the outer portions of the bean cook more than they need to and may get undesirably fragile.

Soaking Times Depend on Temperature Medium-sized beans absorb more than half of their total water capacity in the first two hours of soaking, and plateau at about double their original weight after 10–12 hours. As the soaking temperature goes up, absorption accelerates; and if the beans are first blanched for 1.5 minutes in boiling water, the subsequent water absorption takes only two to three hours in cool water, because the blanching rapidly hydrates the seed coat that controls water movement.

Salt and Baking Soda Speed Cooking Cooking times can be reduced even more by adding various salts to the soaking water. Plain salt at a concentration around 1% (10 g/l, or 2 teaspoons/qt) speeds cooking greatly, apparently because the sodium displaces magnesium from the cell-wall pectins and so makes them more easily dissolved. Baking soda at 0.5% (1 teaspoon/qt) can reduce the cooking time by nearly 75%; it contains sodium and in addition is alkaline, which facilitates the dissolving of the cell-wall hemicelluloses. Of course, added salts affect both the taste and texture of the cooked beans. The alkalinity of baking soda can give an unpleasantly slippery mouth feel and soapy taste. And salt reduces the swelling and gelation of starch granules within beans, which means that it favors a mealy internal texture over a creamy one.

Pressure Cooking Thanks to its temperature of around 250ºF/120ºC, pressure cooking can cut the cooking time of beans and peas by half or more. Salt-presoaked beans may take just 10 minutes.

Persistently Hard Beans One problem that cooks commonly encounter when cooking dry beans is that some batches take unusually long to soften, or never quite do soften. This may have been caused by growing conditions on the farm, or storage conditions after harvest.

“Hard-seed” is a characteristic found in beans when temperatures are high and humidity and water supply are low during the growing season. The outer seed coat gets very water-resistant, so it takes much longer for water to move into the bean interior. Hard-seed beans are usually smaller than normal beans, so they can sometimes be avoided by picking over the beans and discarding the smallest ones before cooking.

“Hard-to-cook” beans, on the other hand, are normal when harvested, but become resistant to softening when they’re stored for a long time — months — at warm temperatures and high humidities. This resistance results from a number of changes in bean cell walls and interiors, including the formation of woody lignin, the conversion of phenolic compounds into tannins that cross-link proteins, and the denaturation of storage proteins to form a water-resistant coating around the starch granules. There’s no way to reverse these changes and make hard-to-cook beans as soft as regular beans. And there’s no way to spot them before cooking. Once cooked, they’re likely to be smaller than normal and so may be picked out before serving.

The Composition of Dry and Sprouted Legumes

Legume Seed

Water

Protein

Carbohydrate

Oil

Common bean

14

22

61

2

Fava bean

14

25

58

1

Lima bean

14

20

64

2

Mung bean

14

24

60

1

sprout

90

4

7

0.2

Soybean

10

37

34

18

sprout

86

6

6

1

Lentil

14

25

60

1

Chickpea

14

21

61

5

Pea

14

24

60

1

Roasting Though most legumes are cooked in liquid to soften their starch and cell walls, a few are parched in dry heat to create a crisp texture. Peanuts are the most commonly roasted of the legumes, thanks to their nut-like oil content and relatively tender cotyledons. Other beans with lower oil contents, notably soybeans and chickpeas, are also roasted to make a nut-like seed. Because their cotyledons are harder, they’re soaked in water first, then roasted. The initial high temperature and moisture soften the cotyledon cell walls and starch granules; continued roasting evaporates most of the water to give a crisp rather than hard texture. The roasting can be done in a hot pan or oven, or — as is done in Asia — in sand that has been heated to 500–600ºF/ 250–300ºC. In India, for example, chickpeas are heated to around 180ºF/80ºC, moistened with water, rested for some hours, then roasted in hot sand so that they puff and the seed coat can be rubbed off.

Characteristics of Some
common Legumes

Fava or Broad Beans The fava bean or broad bean, Vicia faba, is the largest of the commonly eaten legumes, and was the only bean known to Europe until the discovery of the New World. It apparently originated in west or central Asia, and was among the earliest domesticated plants. Larger cultivated forms have been found in Mediterranean sites dating to 3000 BCE. There are several sizes, the largest of which seems to have been developed in the Mediterranean region around 500 CE. China is the world’s largest producer.

Fava beans are unusual in having a thick, tough seed coat that’s often removed from both the meaty cotyledons of the unripe green seeds and from the hard dry seeds. A blanching in alkaline water loosens and softens the coat. In Egypt, the popular dish called ful medames is made by boiling the mature beans until soft, then flavoring with salt, lemon juice, oil, and garlic. Mature fava beans are also sprouted, then boiled to make a soup.

Favism Eating fava beans is the cause of a serious disease, favism, in people who have an inherited deficiency of a particular enzyme. Most victims are children who live in the southern Mediterranean and Middle East, or whose ancestors came from that region. When they are exposed to two unusual amino-acid relatives (vicine and convicine) in the beans and in the flower pollen, their bodies metabolize these chemicals to forms that damage their red blood cells and cause serious, sometimes fatal anemia. The enzyme deficiency also turns out to suppress the growth of the malaria parasite in red blood cells, so it may actually have been an advantageous genetic trait before malaria was brought under control.

Chickpea or Garbanzo Chickpeas are a native of arid southwest Asia, and like the fava bean, pea, and lentil have been cultivated for about 9,000 years. There are two general types, desi and kabuli. Desi are closer to the wild chickpea, with small seeds, a thick, tough seed coat, and a dark color from abundant phenolic compounds. They’re the main variety grown in Asia, Iran, Ethiopia, and Mexico. The kabuli type, more common in the Middle East and Mediterranean, is larger, cream-colored, with a thin, light seed coat. There are also varieties with dark green cotyledons. Chickpeas are notable among the legumes for being about 5% oil by weight; most others are 1–2%.

The name comes from the bean’s Latin name, cicer; in the botanical name, Cicer arietinum, the second word means “ram-like” and refers to the seed’s resemblance to a ram’s head, complete with curling horns. The Spanish garbanzo derives from the Greek name. Today, this legume is a frequent ingredient in many Middle Eastern and Indian dishes. Hummus is a chickpea paste flavored with garlic, paprika, and lemon that is popular in the eastern Mediterranean; in parts of Italy, flatbreads are made from chickpea flour. Chickpeas are the most important legume in India, where they’re hulled and split to make chana dal, ground into flour for papadums, pakoras, and other fried goods, and are boiled, roasted, and sprouted.

Common Bean, Lima Bean, Tepary Bean The common bean, lima bean, and tepary bean are the important domesticated species of the 30 or so species in the Central American genus Phaseolus.

Common Bean The most important species of Phaseolus is P. vulgaris, or the common bean. The ancestral plant was a native of southwestern Mexico, and the highest consumption of the common bean is still in Latin America. It first came under cultivation about 7,000 years ago, and gradually diffused both north and south, reaching the major continents about 2,000 years ago, and Europe during the age of exploration. The common bean has been developed into many hundreds of varieties of different sizes, shapes, seed-coat colors and color patterns, shininess, and flavors. Most large-seeded varieties (kidney, cranberry, large red, and white) came originally from the Andes, and became established in the American Northeast, Europe, and Africa; smaller-seeded central American types (pinto, black, small red, and white) were concentrated in the American Southwest. In the United States, there are more than a dozen commercial categories based on color and size. Beans are cooked in many ways: simply boiled, made into stews, soups, pastes, cakes, and sweet desserts.

Popping Bean A special kind of common bean is the nuña, or popping bean, which has been cultivated for several thousand years in the high Andes. It can be popped by just 3–4 minutes of high dry heat — a great advantage in the fuel-poor mountains — or in the microwave oven. It doesn’t expand nearly as much as popcorn and remains fairly dense, with a powdery texture and nutty flavor.

Lima Bean The use of the common bean in Peru was predated by the larger lima bean — the name derives from Peru’s capital — which was native to Central America and domesticated somewhat later than the common bean. Both species were exported to Europe by Spanish explorers. The lima bean was introduced to Africa via the slave trade, and is now the main legume of that continent’s tropics. The wild type and some tropical varieties contain potentially toxic quantities of a cyanide defense system, and must be thoroughly cooked to be safe (common commercial varieties are cyanide-free). Lima beans are eaten both fresh and dried.

Tepary Bean Tepary beans, small brown natives of the American southwest, are unusually tolerant of heat and water stress. They’re especially rich in protein, iron, calcium, and fiber, and have a distinctive, sweet flavor reminiscent of maple sugar or molasses.

Lentil The lentil is probably the oldest cultivated legume, contemporaneous with wheat and barley and often growing alongside these grasses. Its native ground is arid Southwest Asia, and it’s now commonly eaten across Europe and Asia. Most lentils are produced in India and Turkey, with Canada a distant third. The Latin word for lentil, lens, gives us our word for a lentil-shaped, or doubly convex, piece of glass (the coinage dates from the 17th century). Lentils contain low levels of antinutritional factors and cook quickly.

Lentils are divided into two groups: varieties with flat and large seeds, 5 mm or more across, and varieties with small, more rounded seeds. Large varieties are more commonly grown, while the small, finer-textured ones include the prized green French lentille du Puy, the black beluga, and the green Spanish pardina. There are varieties with brown, red, black, and green seedcoats; most have yellow cotyledons, though some are red or green. Green seed coats can turn brown with age and during cooking, thanks to the clustering of phenolic compounds into large pigmented complexes (p. 269). Because they are flat and thin, with thin seed coats, cooking water only has to penetrate a millimeter or two from each side, so lentils soften much more quickly than most beans and peas, in an hour or less.

Traditional lentil dishes include Indian masoor dal, whole or hulled and split red lentils cooked into a porridge, and Middle Eastern koshary or mujaddharah, a mixture of whole lentils and rice.

Pea, Black-eyed Pea, Pigeon Pea

Pea The pea has been cultivated for around 9,000 years and spread quite early from the Middle East to the Mediterranean, India, and China. It’s a cool-climate legume that grows during the wet Mediterranean winter and in the spring of temperate countries. It was an important protein source in Europe in the Middle Ages and later, as the old children’s rhyme attests: “Pease porridge hot, Pease porridge cold, Pease porridge in the pot, Nine days old.” Today, two main varieties are cultivated: a starchy, smooth-coated one that gives us dried and split peas, and a wrinkly type with a higher sugar content, which is usually eaten when immature as a green vegetable. Peas are unusual among legumes in retaining some green chlorophyll in their dry cotyledons; their characteristic flavor comes from a compound related to the aroma compound in green peppers (a methoxy-isobutyl pyrazine).

Black-eyed Pea The so-called black-eyed pea or cowpea is not really a pea, but an African relative of the mung bean that was known to Greece and Rome and brought to the southern United States with the slave trade. It has an eye-like anthocyanin pigmentation around the hilum, and a distinctive aroma. A variety that produces a very long pod and small seeds is the yard-long bean, a common green vegetable in China (p. 336).

Pigeon Pea Pigeon pea is a distant relative of the common bean, native to India, and now grown throughout the tropics. In India it’s called toor dal or redgram because the tough seed coat of many varieties is reddish brown, though it’s most often hulled and split, and the cotyledons are yellow. It’s been cultivated for around 2,000 years, and is made into a simple porridge. Like the other grams, it contains little in the way of antinutritional factors.

Mung Bean, Black Gram, Azuki

The Grams The legume genus Vigna, which is native to the Old World, provides the small-seeded “grams” of India and a few other Asian and African seeds. Most of them have the advantages of being small, quick-cooking, and relatively free of antinutritional and discomforting compounds. Green gram, or mung beans, are native to India, spread early on to China, and are now the most widely grown of this group thanks to the popularity of their sprouts. Black gram or urad dal is the most prized of the legumes in India, where it has been cultivated for more than 5,000 years and is eaten whole, split and dehulled, and ground into flour for cakes and breads.

Rice beans are eaten primarily in Thailand and elsewhere in Indochina. The African bambara groundnut resembles the peanut in being borne underground and containing oil, but it isn’t nearly as rich as the peanut. In West Africa, the seeds are eaten fresh, canned, boiled, roasted, and made into porridges and cakes.

Azuki Bean Azuki or adzuki (Chinese chi dou) is an East Asian species of Vigna, V. angularis, about 8 by 5 by 5 mm, and most commonly a deep maroon color, which makes it a favorite ingredient for festive occasions. It was cultivated in Korea and China at least 3,000 years ago, and taken later to Japan; it’s now the second most important legume after the soybean in both Korea and Japan. Azuki are a favorite sprouting seed, and are also candied, infused with sugar to make a dessert topping, and used as a base for a hot drink. In Japan most of the azuki crop is made into an, a sweet paste composed of equal parts sugar and ground twice-boiled azuki, which are kneaded together.

Lupins Lupins, lupini in Italian, come from several different species of Lupinus (albus, angustifolius, luteus). They’re unusual because they contain no starch — they’re 30–40% protein, 5–10% oil, and up to 50% soluble but indigestible carbohydrates (soluble fiber, p. 258). Though there are some “sweet” types that require no special processing, many varieties contain bitter and toxic alkaloids and so are soaked in water for up to several days to leach these substances out. They’re then boiled until soft, and served in oil, or toasted and salted. A New World species, L. mutabilis, grown in the Andes, has a protein content approaching 50% of the dry seed weight.

Soybeans and Their
Transformations

Finally, the most versatile legume. Soybeans were domesticated in northern China more than 3,000 years ago, and eventually became a staple food throughout much of Asia; their spread was probably contemporary with and encouraged by the vegetarian doctrine of Buddhism. They were little known in the West until late in the 19th century, but today the United States supplies half of the world production, with China in fourth place after Brazil and Argentina. However, most U.S. soybeans feed not people but livestock, and much of the rest are processed to make cooking oil and a host of industrial materials.

The soybean’s many guises have been inspired by both its great virtues and its defects. Soybeans are exceptionally nutritious, with double the protein content of other legumes, a near-ideal balance of amino acids, a rich endowment of oil, and a number of minor constituents that may contribute to our long-term health (p. 485). At the same time, they’re pretty unappealing. They contain abundant antinutritional factors and gas-producing oligosaccharides and fiber. When boiled in the usual way, they develop a strong “beany” flavor. And when cooked whole as other beans are, they don’t become appealingly creamy; since they contain a negligible amount of starch, their texture remains somewhat firm. The Chinese and others developed two basic ways of making soybeans more palatable: extracting their protein and oil in the form of a milk and then concentrating them in cheese-like curds; and encouraging the growth of microbes that consume undesirable substances and generate an appealing flavor. The results were bean curd and soymilk skins; and soy sauce and miso, tempeh and natto.

Fresh Soybeans One other way to make soybeans more palatable is to eat them before they’re fully mature, when they’re sweeter, contain lower levels of gassy and antinutritional substances, and have a less pronounced beany flavor. Fresh soybeans, Japanese edamame or Chinese mao dou, are specialized varieties harvested at 80% maturity, still sweet and crisp and green, then boiled for a few minutes in salted water. Green soybeans are around 15% protein and 10% oil.

Soybean Milk The traditional method for making soymilk is to soak the beans until soft, grind them, and either sieve out the solids and cook the milk (China) or cook the slurry and then sieve out the solids (Japan). The result is a watery fluid filled with soy proteins and microscopic droplets of soy oil. Either method results in a strong soy flavor. The modern method that minimizes enzyme action and soy flavor is to soak the dry beans (an hour at 150ºF/65ºC allows them to absorb their full weight in water without significant cell damage), and then either quickly cook them to 180–212ºF/80–100ºC before grinding, or grind them in that temperature range in a preheated grinder and preheated water.

In the West, soymilk has become a popular alternative to cow’s milk, with a roughly similar protein and fat content, but the fat less saturated (soy milk must be fortified with calcium in order to be a good nutritional substitute). But it is dilute, textureless, bland, and not very versatile. The Chinese found two ways to make it more interesting (and to remove the gas-causing oligosaccharides): coagulate the milk into surface skins, or coagulate it into curd.

Soymilk Skin When animal or seed milks are heated in an uncovered pot, a skin of coagulated protein forms on the surface. The skin forms because proteins unfolded by the heat concentrate at the surface, get tangled up with each other, and then lose their moisture to the dry room air. As they dry, they get even more tightly tangled, and form a thin but solid protein sheet, entrapping oil droplets and developing a fibrous, chewy texture.

Such skins are usually an annoyance, but some cultures make a virtue of them and turn them into a dish. The Indians do this with cow’s milk, and for several centuries the Chinese have been using soymilk to make dou fu pi, the Japanese yuba, which they layer together to form a variety of sweet and savory products, some of them shaped into flowers, fish, birds, even pigs’ heads. The skins are also meltingly delicious when eaten just as they’re taken from the milk. At some Japanese restaurants, a small pot of soy milk is heated at the table so diners can remove and eat the skins as they form, then add a pinch of salts to the remaining liquid and coagulate it into soft tofu.

Bean Curd, or Tofu Bean curd is curdled soy milk, a concentrated mass of protein and oil formed by coagulating the dissolved proteins with salts that yoke them and the protein-coated oil droplets together. Bean curd was invented in China around 2,000 years ago, was well known by 500 CE, and became a daily food beginning around 1300. Chinese bean curd is traditionally coagulated with calcium sulfate, Japanese bean curd and bean curd from coastal regions of China with what the Japanese call nigari, a mixture of magnesium and calcium salts left over when table salt, sodium chloride, is crystallized from seawater.

Making Bean Curd To make bean curd, cooked soy milk is cooled to about 175ºF/78ºC, then coagulated with calcium or magnesium salts dissolved in a small amount of water. The coagulation takes 8–30 minutes. When the delicate, cloud-like curds have formed, the remaining “whey” is ladled off, or the curd is broken up to release water and drained. The resulting mass is then pressed for 15–25 minutes while still quite hot, around 160ºF/70ºC, in order to form a cohesive mass that’s around 85% water, 8% protein, and 4% oil. In commercial production, the curd is cut into blocks, packaged in water, and the packages pasteurized by immersion in hot water.

Soft or silken tofu, with a custard-like texture, is made by coagulating the soymilk in the package so that the curd remains intact, full of moisture, and delicate.

Freezing Bean Curd Tofu is one of the few foods that can be usefully altered by freezing. When it freezes, the coagulated proteins become even more concentrated, and the solid ice crystals form pockets in the protein network. When the frozen curd thaws, the liquid water flows from the toughened spongy network, especially when the curd is pressed. The sponge is then ready to absorb flavorful cooking liquids, and has a chewier, meatier texture.

Fermented Bean Curd Sufu (tou fu ru, fu ru) is soybean curd fermented by molds in the genera Actinomucor and Mucor, producing the Chinese and vegetarian equivalent of mold-ripened milk cheeses.

Fermented Soybean Products: Soy Sauce, Miso, Tempeh, Natto The great appeal of miso and soy sauce, long-fermented soy products, is their strong, distinctive, and delicious flavor. It develops when microbes break down the bean proteins and other components and transform them into savory substances that then react with each other to generate additional layers of flavor. Tempeh and natto are quick-fermented soy products with their own unusual qualities.

Two-Stage Fermentations Asian mold fermentations generally involve two distinct stages. In the first, dormant green spores of Aspergillus molds are mixed with cooked grains or soybeans, which are then kept warm, moist, and well aerated. The spores germinate and develop into a mass of thread-like hyphae, which produce digestive enzymes that break down the food for energy and building blocks. The second stage begins after about two days, when the enzymes are at their peak. The mixture of food and hyphae, called chhü in China and koji in Japan, is now immersed in a salt brine, often along with more cooked soybeans. In the oxygen-poor brine, the molds die, but their enzymes continue to work. At the same time, microbes that thrive in the absence of oxygen — salt-tolerant lactic acid bacteria and yeasts — grow in the brine, consume some of the building blocks, and contribute their own flavorful by-products to the mixture.

The Origins of Miso and Soy Sauce The first foods that the ancient Chinese fermented in brine were pieces of meat or fish. These were eventually replaced by whole soybeans around the 2nd century BCE. Soy paste became the major condiment around 200 CE and remained so through around 1600, when it was replaced by soy sauce. Soy sauce began as a residue resulting when soy paste was made with excess liquid, but it became more popular than the paste, and by 1000 was prepared for its own sake.

Fermented soy pastes and soy sauce were carried by Buddhist monks to Japan, where sometime around 700 CE a new Japanese name, miso — mi meaning flavor — was given to distinctive Japanese versions of the paste. These involved the use of a grain-based koji that provided sweetness, alcohol, finer aromatics, and delicacy. Until the 15th century, Japanese soy sauce was simply the excess fluid, or tamari, ladled from finished soybean miso. By the 17th century, the now-standard formula of roasted cracked wheat and soybeans had been established for making the sauce, and the resulting product given a new name, shoyu. Shoyu began to appear on western tables as an exotic and expensive item by the 17th century.

Miso Miso is used as a soup base, as a seasoning for various dishes, in marinades, and as a medium for pickling vegetables. There are dozens of different varieties.

Miso is made by cooking a grain or legume — usually rice, sometimes barley, sometimes soybean — and fermenting it in shallow trays with koji starter for several days to develop enzymes. The resulting koji is then mixed with ground cooked soybeans, salt (5–15%), and a dose of an earlier batch of miso (to provide bacteria and yeasts). In traditional miso making, the mixture is allowed to ferment (and eventually age) in barrels for months to years at a warm 86–100ºF/30–38ºC. Various lactic acid bacteria (Lactobacilli, Pediococci) and salt-tolerant yeasts (Zygosaccharomyces, Torulopsis) break down the seed proteins, carbohydrates, and oils and produce a host of flavor molecules and flavor precursors. Browning reactions generate deeper layers of flavor and color.

Traditionally made miso ends up with a rich, savory, complex flavor dominated by sweet and roasted notes, and sometimes by esters reminiscent of pineapple and other fruits. Modern industrial production cuts the fermentation and aging from months to a few weeks, and compensates for the resulting lack of flavor and color with various additives.

Soy Sauce Soy sauce is made in several different styles today. Broadly speaking, the flavor of traditional soy sauce depends on the proportions of soybeans and wheat. Most Chinese soy sauces, and Japanese tamari, are made primarily or exclusively from soybeans. Japanese soy sauce is generally made from an even mixture of soybeans and wheat, and the starch from the wheat gives it a characteristic sweetness, a higher alcohol content, and more alcohol-derived aromatics. Shiro, or “white” soy sauce, lighter in color and flavor, is made with more wheat than soybeans.

Making Japanese Soy Sauce

Japanese Soy Sauce Most of the soy sauce sold in the West is made in Japan or in the Japanese style, which is summarized in the box on p. 498. During the initial brief fermentation, the Aspergillus mold produces enzymes that will break down wheat starch into sugars, wheat and soy proteins into amino acids, and seed oils into fatty acids. Then during the longer main fermentation, these enzymes do their work; yeasts produce alcohol and a range of taste and aroma compounds; and bacteria produce lactic, acetic, and other acids, and yet other aromas. Over time, the various enzymes and microbial products also react with each other, the sugars and amino acids forming roasty-smelling pyrazines, acids and alcohols combining to form fruity esters. The high-temperature pasteurization develops yet another layer of flavor by encouraging browning reactions between amino acids and sugars. The result is a liquid that’s salty, tart, sweet, savory (from a high concentration of amino acids, mainly glutamic acid), with a rich aroma. Several hundred aroma molecules have been identified in soy sauce, with roasty compounds (furanones and pyrazines), sweet maltol, and a number of meaty sulfur compounds among the more prominent. All in all, soy sauce is a concentrated, mouth-filling liquid, a versatile flavor enhancer for other foods.

Tamari Tamari names a kind of Japanese soy sauce closest to its Chinese original: made with little or no wheat, and therefore poor in alcohol and fruity esters derived from it, but with a darker color and richer flavor thanks to the higher concentration of soybean amino acids. Today tamari is sometimes stabilized with added alcohol, which makes its aroma closer to that of ordinary shoyu. Even stronger than true tamari is twice-fermented saishikomi, made by making up the mash not with salt water, but with a previous batch of soy sauce.

“Chemical” Soy Sauce Industrial producers have been making nonfermented approximations of soy sauce since the 1920s, when the Japanese first used chemically modified soy protein (“hydrolyzed vegetable protein”) as an ingredient. Nowadays, defatted soy meal, the residue of soybean oil production, is broken down — hydrolyzed — into amino acids and sugars with concentrated hydrochloric acid. This caustic mixture is then neutralized with alkaline sodium carbonate, and flavored and colored with corn syrup, caramel, water, and salt. Such quick “chemical” soy sauce has a very different character from the slow fermented version, and is usually blended with at least some genuine fermented soy sauce to make it palatable.

OPPOSITE: Making soy sauce. The more involved and time-consuming fermentation produces a much more flavorful result than the quick chemical production method.

To make sure you’re buying genuine soy sauce, read the label carefully, and avoid products that include added flavorings and colors.

Tempeh Tempeh was invented in Indonesia, and unlike miso and soy sauce is not a salty preserved condiment but an unsalted, quick-fermented, perishable main ingredient. It’s made by cooking whole soybeans, forming them into thin layers, and fermenting with a mold, Rhizopus oligosporus or R. oryzae, for 24 hours at a warm, tropical temperature (85–90ºF/30–33ºC). The mold grows and produces thread-like hyphae, which penetrate the beans and bind them together, and digest significant amounts of protein and oil to flavorful fragments. Fresh tempeh has a yeasty, mushroomy aroma; when sliced and fried, it develops a nutty, almost meaty flavor.

Natto

Natto has been made in Japan for at least 1,000 years, and is notable for being distinctly alkaline (from the breakdown of amino acids into ammonia) and for developing a sticky, slippery slime that can be drawn with the tip of a chopstick into threads up to 3 ft/1 m long! As with tempeh, no salt is used and the product is perishable. The whole beans are cooked, inoculated with a culture of the bacterium Bacillus subtilis natto, and held at about 100ºF/40ºC for 20 hours. Some bacterial enzymes break down proteins into amino acids and oligosaccharides into simple sugars, while others produce a range of aroma compounds (buttery diacetyl, various volatile acids, nutty pyrazines), as well as long chains of glutamic acid and long branched chains of sucrose, which form the slimy strings. Natto is served atop rice or noodles, in salads and soups, or cooked with vegetables.

Some Traditional Fermented Soybean Preparations

Nuts and Other
Oil-Rich Seeds

From the first, the English word nut meant an edible seed surrounded by a hard shell, and this remains the common meaning. Botanists later appropriated the word to refer specifically to one-seeded fruits with a tough, dry fruit layer rather then a fleshy, succulent one. Under this restricted definition, among common nuts only acorns, hazelnuts, beechnuts, and chestnuts qualify as true nuts. The details of anatomy aside, the various seeds that we call nuts differ from grains and legumes in three important ways: they’re generally larger, richer in oil, and require little or no cooking to be edible and nourishing. This combination of qualities made nuts an important source of nourishment in prehistoric times. Today, they’re especially appreciated for their characteristic rich flavor.

Walnuts, hazelnuts, chestnuts, and pine nuts all have both Old World and New World species, because nut-bearing trees have been around a lot longer than the other food plants, long enough that they existed before North America and Europe split apart some 60 million years ago. Over the last few centuries, humans have spread their prized nut species to nearly every region on the globe with a suitable climate. California has become the largest producer of southwest Asian almonds and walnuts, South American peanuts are grown throughout the subtropics, and Asian coconuts throughout the tropics.

Nut Structures and Qualities

The bulk of most nuts consists of the embryo’s swollen storage leaves, or cotyledons, but coconuts and pine nuts are monolithic masses of endosperm, and the Brazil nut is a swollen embryonic stem. Unlike most grains and legumes, nuts are delicious when eaten in their dry, nutrient-concentrated state, somewhat crisped and browned by a quick roasting. Their weak cell walls make them tender, their low starch content prevents them from seeming floury, and their oil gives them a mouth-watering moistness.

An important feature of the nuts is the skin, a protective layer of varying thickness that adheres to the kernel. Chestnut skins are thick and tough, hazelnut skins papery and brittle. The nut skin is usually reddish-brown in color and astringent to the taste. Both qualities are due to the presence of tannins and other phenolic compounds, which may make up a quarter of the skin’s dry weight. Many of these same phenolic compounds are effective antioxidants and so nutritionally valuable. But because they’re astringent and discolor other ingredients (walnut skins turn breads purple-gray), cooks often remove the skins from nuts.

The chestnut, with its shell and tough, adherent seed coat.

The Nutritional Value of Nuts

Nuts are very nutritious. After pure fats and oils, they’re the richest foods that we eat, averaging around 600 calories (kcal) per quarter-pound/100 gm; by comparison, fatty beef averages 200 calories, and dry starchy grains 350. Nuts can be 50% or more oil, 10–25% protein, and are a good source of several vitamins and minerals and of fiber. Notable among the vitamins is the antioxidant vitamin E, especially concentrated in hazelnuts and almonds, and folic acid, which is thought to be important for cardiovascular health. Most nut oils are made up primarily of monounsaturated fatty acids, and have more polyunsaturates than saturated fats (exceptions are coconuts with a large dose of saturated fat, and walnuts and pecans, which are predominantly polyun-saturated). And nut seed coats are rich in antioxidant phenolic compounds. This cluster of characteristics — a favorable balance of fats, copious antioxidants, and folic acid — may explain why epidemiological surveys have found nut consumption to be associated with a reduced risk of heart disease.

Nut Flavor

Nuts provide us with a distinctive, appealing, and versatile set of flavors. Nuttiness is a cluster of qualities: slightly sweet, slightly fatty, slightly roasted or toasted; a delicate flavor, yet with some depth. The nuts’ ample endowment of oil is key to their character; the less rich grains take on a pleasant flavor when simply toasted dry, but develop an added dimension when cooked in oil or fat. The quality of nuttiness complements many other foods, whether savory or sweet, all the way from fish to chocolate.

Most nuts contain at least traces of free sugars. Some contain more than a trace and are noticeably sweet; these include chestnuts, cashews, pistachios, and pine nuts.

Handling and Storing Nuts

The same high oil content that makes nuts nutritious and delicious also makes them much more fragile than grains and legumes: that oil readily absorbs odors from the surroundings, and goes rancid when it’s split into its component fatty acids and the fatty acids are then fragmented by oxygen and light. The fatty acids have an irritating effect on the mouth, while their fragments have cardboard, paint-like aromas. Walnuts, pecans, cashews, and peanuts are rich in fragile polyunsaturated fats and are especially susceptible to staling. Fat rancidity is favored by bruising, light, heat, and moisture, so it’s best to store nuts in opaque containers at cool temperatures. Shell-less kernels are best refrigerated. Because they contain very little water and so don’t suffer from the formation of damaging ice crystals, nuts can be frozen for long keeping. Storage containers should be truly air-and odor-tight — glass jars, for example, rather than permeable plastic bags.

Nuts are at their best when they’re freshly harvested, usually in late summer and fall (early summer for almonds). Newly harvested nuts are too moist to keep without being vulnerable to molds, so producers dry them with as little heat as possible, usually at 90–100ºF/32–38ºC. When buying fresh nuts, look for an opaque, off-white interior. Any translucency or darkening is a sign that the cells are damaged, oil has been released, and rancidity is developing.

Cooking Nuts

Unlike most other seed foods, nuts are good simply oven-toasted or fried for a few minutes, which transforms the chewy, pliable, bland, pale seeds into crisp, flavorful, browned morsels. They can also be roasted in the microwave oven. Since nuts are small and dry, frying is generally done at relatively low temperatures for relatively short times, 250–350ºF/120–175ºC for a few minutes, with lower temperatures and longer times for large nuts (Brazil nuts, macadamias). Doneness should be judged by color and flavor, not texture; heat softens the tissue, which gets crisp as it cools. Stop the cooking just short of the ideal doneness, since nuts continue to cook for some time after they’re taken from the heat. Nuts are less brittle when they’re warm, so slicing them while warm can give cleaner pieces with fewer flakes and crumbs.

Commercially prepared nuts are often roasted, salted with special flake-shaped particles that have more of a surface to adhere to the nut, then coated with a layer of oil or a protein-emulsifier blend to help retain the salt. Peanuts are salted in the shell by being soaked in brine under a vacuum, which pulls the air from inside the shell and forces the brine in.

Removing Skins Many preparations call for nut skins to be removed so that they don’t discolor the dish or add unwanted astringency. Thin skins — those on peanuts and hazelnuts, for example — can often be made brittle enough to rub off by a brief toasting in the oven. The thicker skins of almonds are toughened and loosened by a minute or two in boiling water. Others can often be removed by immersing the nuts in hot water made alkaline with baking soda (3 Tb soda per quart/45 gm per liter), rubbing the softened skins off (alkalinity helps dissolve hemicellulose cement in the cell walls), then reimmersing the nuts in a dilute acid solution to neutralize the slight amount of absorbed alkaline liquid. The color and astringency of hard-to-remove walnut skins can be lightened significantly by a brief boiling in acidified water, which leaches out tannins and bleaches the color of those that remain. Tough chestnut skins are softened by roasting or boiling in the shell, or by a brief period in the microwave oven. They’re also simply peeled off like the skin of an apple.

Nut Pastes and Butters All dry and fatty nuts can be ground in a mortar or blender into a butter-like paste, with the oil from ruptured cells coating and lubricating the cell fragments and particles of intact cells. One of the most venerable nut pastes is the Middle Eastern tahini, made from ground sesame seeds; it’s used with chickpeas to make hummus, and with eggplant to make baba ghanoush. Throughout the world, nut pastes are added to soups and stews to contribute flavor, richness, and body; almond soups are made in Spain and Turkey, walnut soups in Mexico, coconut soups in Brazil, pecan and peanut soups in the American South.

Nut Oils The oils of a number of nuts are prized for their flavor — walnut oil and coconut oil, for example — and several others as ordinary cooking oils (peanut oil, sunflower seed oil). Oils are extracted from nuts by two different means. “Cold-pressed” or “expeller-pressed” nut oils are made by crushing the nut cells and forcing the oil out with mechanical pressure. The nuts get hot from the pressure and friction, but generally don’t exceed the boiling point. Solvent-extracted oils are made by dissolving the oil out of the crushed nuts with a solvent at temperatures around 300ºF/150ºC, then separating the oil from the solvent. They are more refined than pressed oils, having fewer of the trace compounds that make oils both flavorful and potentially allergenic (p. 455). Cold-pressed oils are generally used as a flavoring, refined oils as cooking oils. Nut oils have a stronger flavor if the nuts are roasted before extraction. Because they often have a large proportion of fragile polyunsaturated fatty acids, they’re more vulnerable to oxidation than ordinary vegetable oils, and are best kept in dark bottles in the refrigerator. The leftover solids — nut meal or flour — make a flavorful and nutritious contribution to baked goods.

Nut Milks If nuts are ground while dry, their microscopic oil bodies (p. 459) merge and coalesce to make oil the continuous liquid phase of the paste. But if the raw nuts are first soaked in water, then grinding releases the oil bodies relatively intact into the continuous water phase. When the solid nut particles are strained off, this leaves behind a fluid similar to milk, with oil droplets, proteins, sugars, and salts dispersed in water. In medieval Europe, which learned about them from the Arabs, almond milks and creams were both luxurious ingredients and dairy substitutes for fasting days. Today, the most common seed milk is made from coconuts, but it can be made from any oil-rich nut and from soybeans (p. 494).

Modern cooks can use nut milks to make rich and delicious ices, and to enrich sauces and soups. Thanks to the tendency of the nut proteins to coagulate, cooks can thicken nut milks with acid into the equivalent of yogurt, and cook them into a cross between a pudding and custard. Almonds with their high protein content produce the most easily thickened milk. Other nut milks can be boiled to coagulate the proteins into curds, then the curds can be drained of excess fluid, blended until smooth, and heated gently to thicken them further. To impart more flavor to the milk, a small fraction of the nuts can be roasted before grinding.

Characteristics
of Some Common Nuts

Almonds Almonds are the world’s largest tree-nut crop. They’re the seed of a plum-like stone fruit, or drupe; the tree is a very close relative of the plum and peach. There are several dozen wild or minor species, but the cultivated almond, Prunus amygdalus, came from western Asia and had been domesticated by the Bronze Age. California is now the largest producer. Thanks to their high content of antioxidant vitamin E and low levels of polyunsaturated fats, almonds have a relatively long shelf life.

Almonds are the main ingredient in marzipan, a paste of sugar and almonds finely ground together and molded and dried into decorative shapes, a Middle Eastern invention that became popular in Europe during the medieval Crusades. Leonardo da Vinci made marzipan sculptures for the Milanese court of Ludovico Sforza in 1470, and wrote that he “observed with pain that [they] gobble up all the sculptures I give them, right to the last morsel.” Almond paste is also commonly used as a pastry filling or the base for macaroons, cookies whose only other structural ingredient is egg whites.

Why Almonds Don’t Taste Like Almond Flavoring Curiously, standard domesticated almonds taste delicately nutty, nothing like the strong and distinctive flavoring called “almond extract.” Strong almond flavor is found only in wild or bitter almonds, which are inedibly bitter and toxic. They contain a defensive system that generates deadly and bitter hydrogen cyanide when the kernel is damaged (p. 258). It’s estimated that eating a few bitter almonds at a sitting could kill a child. But it turns out that one by-product of cyanide production is benzaldehyde, a volatile molecule that is the essence of wild almond flavor, and that contributes to the aromas of cherry, apricot, plum, and peach. Our safe “sweet” almond varieties lack both the bitterness and the characteristic aroma.

Bitter almonds are generally unavailable in the United States, while in Europe they’re used like a spice, added in small numbers to flavor marzipan made from sweet almonds, as well as to amaretti cookies, amaretto liqueur, and other dishes. Apricot and peach kernels are readily available alternative sources of benzaldehyde, though they don’t have the intense and otherwise fine flavor of bitter almonds. German cooks make versions of marzipan called persipan with apricot and peach kernels.

Brazil Nuts Brazil nuts are unusually large, an inch/2.5 cm or more long, and double the weight of almonds and cashews. They’re the seeds of a large tree (Bertholletia excelsa, 150 ft/50 m tall, 6 ft/2 m across) native to the Amazon region of South America, where they develop in groups of 8 to 24 inside a hard, coconutsized shell. South American countries are still the main producers. The pods are gathered only after they fall to the ground. Because they weigh about 5 pounds, they can be lethal missiles, and harvesters must carry shields to protect themselves. The edible portion of the seed is an immensely swollen embryonic stem. Thanks to their size and high oil content, two large Brazil nuts are the caloric equivalent of one egg.

Brazil nuts are notable for containing the highest levels of selenium of any food. Selenium helps to prevent the development of cancer, apparently by several different means, including an antioxidant enzyme and by inducing damaged cells to die. However, an overdose is toxic. The World Health Organization recommends a maximum daily selenium intake corresponding to just a half-oz/14 gm of Brazil nuts.

The almond, a close relative of the peach, plum, and cherry, with its stony shell.

Cashews Like the Brazil nut, cashews come from the Amazon region, whose natives gave us the name. But the tree was successfully transplanted to India and East Africa by the Portuguese, and today these regions are the world’s largest producers. The cashew is second only to the almond in world trade. It’s a relative of poison ivy, and that’s why we never see cashews for sale in the shell. The shell contains an irritating oil that must be driven off by heating before the seed can be carefully extracted without contamination. In the producing countries, the seed-containing fruit is often discarded in favor of the swollen stem tip or “false fruit” called the cashew apple, which is enjoyed either fresh, cooked, or fermented into an alcoholic drink.

Cashews are unusual among oily nuts in containing a significant amount of starch (around 12% of their weight), which makes them more effective than most nuts at thickening water-based dishes (soups, stews, Indian milk-based desserts).

Chestnuts Chestnuts come from several different species of large trees in the genus Castanea, which are found in Europe, Asia, and North America. They’re unlike the other common nuts in storing their energy for the future seedling in the form of starch, not oil. Chestnuts are thus usually thoroughly cooked and have a mealy texture. Since prehistory they have been dried, ground into flour, and used in the same way that the starchy cereals are, to make gruels, breads, pastas, cakes, and provide substance in soups. Before the arrival of the potato and corn from the New World, chestnuts were an essential subsistence food in mountainous and marginal agricultural areas of Italy and France. At the opposite extreme, a luxurious chestnut specialty invented in the 17th century is marrons glacés, large chestnuts that are cooked, slowly infused over a day or two with a vanilla-flavored syrup, then glazed with a more concentrated syrup.

The American enjoyment of our native chestnut, Castanea dentata, was brought to a sad end in the early 20th century, when in the course of a few decades, an imported Asian fungal blight wiped out a tree that used to make up 25% or more of the eastern hardwood forest. Today, the world’s leading chestnut producers are China, Korea, Turkey, and Italy.

Because of its high initial moisture content, the chestnut is quite perishable. Chestnuts are best kept covered and refrigerated, and should be eaten fairly quickly. If freshly gathered, however, they should be cured at room temperature for a few days. This improves the flavor by permitting some starch to be converted into sugar before the cells’ metabolism is slowed down.

Coconuts Coconuts are the largest and most important of all nuts. They are the stone of a drupe, the fruit of Cocos nucifera, large (to 100 ft/30 m) tree-like palms that are more closely related to the grasses than to other nut trees. They’re thought to have originated in tropical Asia, but their hardy fruits apparently floated to many parts of the world before humans began to transport them. They were largely unknown to Europe until the early Middle Ages. About 20 billion nuts are produced each year, mainly in the Philippines, India, and Indonesia. The word coconut comes from the Portuguese coco, which means goblin or monkey. The markings on the stem end of the nut can look uncannily like a face. The tiny embryo resides under one of the eyes, through which it grows when it sprouts.

Coconuts consist of a thick fibrous fruit layer, the husk, within which is the seed proper enclosed in a woody shell. The meat and milk constitute the seed’s endosperm, which contains enough nutrients and moisture to support the seedling’s growth for more than a year. The entire fruit may weight 2–5 lb/1–2 kg, of which about a quarter is meat, 15% free water.

Coconut provides a backbone flavor in many tropical cuisines, from southern India and Southeast Asia to Africa and South America. It’s often used in the form of coconut milk, which provides a rich, flavorful liquid in which to cook all kinds of foods, from meats and fish to vegetables and rice. Since the coconut meat can’t be roasted intact, its flavor is developed by carefully toasting small flakes or shreds. Unlike other nuts, which provide crunchiness or smooth richness depending on how finely they’re broken, coconut has a persistent, chewy texture unless toasted and kept very dry.

The distinctive sweet, rich aroma of coconut is created by derivatives of saturated fatty acids called lactones (octa-, deca-, dodeca-, tetradecalactones) — peaches are also flavored by lactones — while roasting generates more generic nutty notes (from pyrazines, pyrroles, furans).

Coconut Development Coconut fruits are borne and mature year-round. At around four months, the nut fills with liquid; at five, it reaches its full size and begins to develop a jelly-like meat; at seven its shell begins to harden, and it’s mature at a year. Immature coconuts, around five to seven months old, offer their own pleasures: a sweet liquid called coconut water (about 2% sugars); and a moist, delicate, gelatinous meat that’s mainly water, sugars and other carbohydrates. In the mature coconut of 11–12 months, the liquid has become less sweet and less abundant, and the meat has become firm, fatty, and white. The meat is about 45% water, 35% fat, 10% carbohydrate, 5% protein.

The coconut. This massive seed is borne in a thick, dry husk and contains both solid and liquid endosperm to feed the small embryo, which emerges from one of the three “eyes” at the end of the shell.

Coconut Meat and Milk A good fresh coconut should feel heavy and contain enough liquid to slosh audibly. If coconut meat is pounded in a mortar or ground finely in a blender, it forms a thick paste consisting of microscopic oil droplets and cell debris suspended in water, which makes up about half the volume. Coconut milk is made by mixing the paste with some additional water and straining to remove the solid particles. Left to stand for an hour, this milk separates into a fat-rich cream layer and a thin “skim” layer. Coconut milk can also be made from dried shredded coconut, and is readily available canned.

Coconut Oil For part of the 20th century, coconut oil was the most important vegetable oil in the world. It can be produced in large quantities, is very stable, and has a melting point similar to that of milk fat. But the very quality that makes it stable and versatile also made it appear to be nutritionally undesirable. The fats that make up coconut oil are nearly 90% saturated (15% caprylic and capric, 45% lauric, 18% myristic, 10% palmitic, and just 8% monounsaturated oleic), which means that they raise blood cholesterol levels. During the 1970s and ’80s, manufacturers of processed foods therefore replaced coconut oil with less saturated, partly hydrogenated seed oils — which now turn out to contain undesirable trans fatty acids (p. 38).

Given our current and broader understanding of other dietary influences on heart disease (p. 255), there’s no reason not to enjoy the coconut’s riches as part of a balanced diet that includes plenty of protective fruits, vegetables, and other seeds.

Ginkgo Nuts Gingko nuts are the starchy kernels of Ginkgo biloba, the last survivor of a tree family that was prominent during the age of the dinosaurs. The nuts are borne inside fleshy fruits that develop a strong rancid smell when ripe. In Asia, the tree’s home, the fruits are fermented in vats of water to soften and remove the pulp, and the seeds are washed, dried, and roasted or boiled, either in-shell or shelled. The kernel has a distinctive but mild flavor.

Hazelnuts Hazelnuts come from a few of the 15 species of mainly bushy trees in the northern-hemisphere genus Corylus. Corylus avellana and C. maxima are native to temperate Eurasia and were widely exploited in prehistoric times for their nuts and rapidly produced shoots, which were used as walking sticks and a surface for marshy ground. A much taller tree, C. colurna, accounts for much of the production in the Black Sea region of Turkey. Another term for the nut is “filbert,” which in the United Kingdom is applied to the more elongated varieties, and which may come from St. Philibert’s Day in late August, when hazelnuts begin to ripen. The late Roman cookbook of Apicius called for hazelnuts in sauces for birds, boar, and mullet; they’re an alternative to almonds in Spanish picada and romesco sauces, and an ingredient in the spicy Egyptian spread called dukka and the Italian liqueur frangelico. Hazelnuts remain especially popular in Europe, where Turkey, Italy, and Spain are the main producers. In the United States, nearly all hazelnuts are produced in Oregon.

The distinctive aroma of hazelnuts comes from a compound dubbed filbertone (heptenone), which is present in small quantities in the raw nut, but increases 600-to 800-fold when the nuts are fried or boiled.

Macadamia Nuts Macadamia nuts are newcomers to the world’s table. They come from two evergreen tropical trees (Macadamia tetraphylla and M. integrifolia) native to northeastern Australia, where the aborigines enjoyed them for thousands of years before they were noticed and named by Europeans (for John Macadam, a Scots-born chemist, in 1858). Macadamias were introduced to Hawaii in the 1890s, and became commercially significant there around 1930. Today Australia and Hawaii are the main producers, but their output remains relatively small, and macadamias are therefore among the most expensive nuts. Because their shells are extremely hard, they are sold almost exclusively out-of-shell, often packed in cans or bottles to protect them from air and rancidity. Macadamias have the highest fat content of the tree nuts, and it’s mostly monounsaturated (65% oleic acid). Their flavor is mild and delicate.

Peanut This popular nut is not a nut, but the seed of a small leguminous bush, Arachis hypogaea, which pushes its thin, woody fruit capsules below ground as they mature. The peanut was domesticated in South America, probably Brazil, around 2000 BCE, and was an important crop in Peru before the time of the Incas. In the 16th century, the Portuguese took it to Africa, India, and Asia, and it soon became a major source of cooking oil in China (peanuts have double the oil content of soybeans). It wasn’t until the 19th century that Americans thought of peanuts as anything but animal feed, and not until the early 20th century that the remarkable agricultural scientist George Washington Carver encouraged southern farmers to replace weevil-ravaged cotton with peanuts.

Today India and China are by far the largest peanut producers, with the United States a distant third. Most Asian peanuts are crushed for oil and meal; in the United States most are eaten as food. Peanuts are now prominent in several Asian and African traditions. Pureed, they lend richness, substance, and flavor to sauces and soups. Whole and pureed peanuts are used in Thai and Chinese noodle dishes, in sweet bun fillings, in Indonesian dipping sauces and sambal condiments, and in West African stews, soups, cakes, and confections. A popular snack food in both Asia and the southern United States is peanuts boiled in salted water. When boiled in their shells, peanuts develop a potato-like aroma, with sweet vanilla highlights thanks to the liberation of vanillin from the shell.

In the United States, four varieties are grown for different purposes: large Virginia and small Valencia for nuts sold in the shell, Virginia and small Spanish for mixed nuts and candies, and Runner for baked goods and peanut butter, since its higher content of monounsaturated fat makes it less vulnerable to rancidity.

Peanut Butter The modern version of peanut butter was apparently developed around 1890 in St. Louis or in Battle Creek, Michigan. Commercial peanut butter is made by heating the nuts to an internal temperature around 300ºF/150ºC to develop flavor, blanching in hot water to remove the skin, and finally grinding them with about 2% salt and up to 6% sugar. The oil can be prevented from separating from the solid peanut particles by adding 3–5% of a hydrogenated shortening that solidifies as the butter cools and forms a host of tiny crystals that hold the very unsaturated, liquid peanut oil in place. Low-fat peanut butter is made by replacing a portion of the peanuts with soy protein and with sugar.

Peanut Flavor Several hundred volatile compounds have been identified in roasted peanuts. The raw seed has a green, bean-like flavor (mainly from green-leaf hexanal and the pyrazine that characterizes peas). The roasted aroma is a composite of several sulfur compounds, a number of generically “nutty” pyrazines, and others, some of which have fruity, flowery, fried, and smoky characters. During storage and staling, the nutty pyrazines disappear and painty, cardboard notes increase.

Peanut Oil Thanks to the productivity of the peanut plant in warm climates, peanut oil is an important cooking oil, especially in Asia. It’s made by steaming the peanuts to inactivate enzymes and soften the cellular structure, then pressing them; the oil is then clarified and sometimes refined to remove some of the distinctive flavor and impurities that would lower the smoke point.

Pecans Pecans are the soft, fatty seeds of a very large tree, a distant relative of the walnut that is native to the Mississippi and other river valleys of central North America, and found as far south as Oaxaca. Carya illinoiensis is one of about 14 species of hickories, and its nuts among the tastiest and easiest to shell. Wild pecans were enjoyed by the native Americans, and apparently made into a kind of milk that was used for drinking, cooking, and possibly fermenting. The earliest intentional plantings may have been made by the Spanish around 1700 in Mexico, and a few decades later the trees were grown in the eastern British colonies. The first improved varieties were made possible in the 1840s by a Louisiana slave named Antoine, who worked out how to graft wood from superior trees onto seedling stocks. Georgia, Texas, and New Mexico are now the largest producers of pecans.

Compared to the walnut, the pecan is more elongated, the cotyledons thicker and smoother, with a larger proportion of meat to shell. As with walnuts, light-skinned varieties are less astringent than dark-skinned. The distinctive flavor of pecans remains somewhat mysterious. In addition to the generic nutty notes of the pyrazines, one study found a lactone (octalactone) that is also present in coconuts.

Pecans and walnuts are among the nuts with the highest oil and unsaturated fatty acid contents. High oil content generally goes along with fragile texture, which means that the kernels are easily bruised, with seepage of oil to the surface and rapidoxidation and staling. Roasting increases the rate of staling by weakening cells and allowing oil to come into contact with the air. Carefully handled, raw pecans can be stored for years in the freezer.

Pine Nuts Pine nuts are gathered from about a dozen of the 100 species of pines, one of the most familiar evergreen tree families in the Northern Hemisphere. Among the more important sources are the Italian stone pine Pinus pinea, the Korean or Chinese pine P. koraiensis, and the southwestern U.S. pinyons P. monophylla and P. edulis. The nuts are borne on the scales of the pine cone, which takes three years to mature. The cones are sun-dried, threshed to shake out the seeds, and the kernels then hulled, nowadays by machine. They have a distinctive, resinous aroma and are rich even for nuts; Asian pine nuts have a higher oil content (78%) than either American or European types (62% and 45% respectively). They’re used in many savory and sweet preparations, and pressed to make oil. In Korea, pine pollen is used to make sweets, and Romanians flavor game sauces with the green cones.

Pistachios Pistachios are the seeds of a native of arid western Asia and the Middle East, Pistacia vera, a relative of the cashew and the mango. Along with almonds, they have been found at the sites of Middle Eastern settlements dating to 7000 BCE. A close relative, Pistacia lentiscus, provides the aromatic gum called mastic (p. 421). Pistachios first became a prominent nut in America in the 1880s, thanks to their popularity among immigrants in New York City. Iran, Turkey, and California are the major producers today.

Pistachios grow in clusters, with a thin, tannin-rich hull around the inner shell and kernel. As the seeds mature, the outer hull turns purple-red and the expanding kernel cracks the inner shell open. Traditionally, the ripe fruits were knocked from the trees and sun-dried, and the hull pigments stained the shell, so the shells were often dyed to make them a uniform red. Today, most California pistachios are hulled before drying, so the shells are their natural pale tan color.

Pistachios are remarkable among the nuts for having green cotyledons. The color comes from chlorophyll, which remains vivid when the trees grow in a relatively cool climate, for example at high elevation, and when the nuts are harvested early, several weeks before full maturity. Pistachios thus offer not only flavor and texture but a contrasting color in pâtés, sausages, and other meat dishes, and in ice creams and sweets. The color is best retained by roasting or otherwise cooking the kernels at low temperatures that minimize chlorophyll damage.

Walnuts Walnuts come from trees in the genus Juglans, of which there are around 15 species native to southwestern Asia, eastern Asia, and the Americas. The most widely cultivated is the Persian or English walnut, Juglans regia, whose seeds have been enjoyed since ancient times in western Asia and Europe, and among tree nuts are second only to almonds in worldwide consumption. In many European languages, the generic term for nut is also the word for walnut. The United States, France, and Italy are the major producers today. Walnuts have long been pressed for their aromatic oil, were once made into milk in Europe and China, and came to provide the rich, flavorful backbone of sauces in Persia (fesenjan), Georgia (satsivi), and Mexico (nogado). In some countries, immature “green” walnuts are harvested in early summer and pickled (England), used to flavor sweetened alcohol (Sicilian nocino, French vin de noix), or preserved in syrup (the Middle East).

Pine nuts. They are borne on the scales of pine cones, and like the coconut, are mainly endosperm tissue rather than cotyledons.

Like its cousins the pecan and hickories, the walnut is the stone of a thin-walled fruit, the edible portion being two lobed, wrinkled cotyledons. Walnuts are exceptionally rich in the omega-3 polyunsaturated linolenic acid, which makes them nutritionally valuable but also especially liable to become rancid; they should be kept in the cold and dark. The aroma of walnuts is created by a complex mixture of molecules derived from the oil (aldehydes, alcohols, and ketones).

Walnut Relatives A North American relative of the Persian walnut, the black walnut (J. nigra) is smaller, with a harder shell and a stronger, distinctive flavor. It was once commonly used to make breads, confections, and ice creams, but it’s difficult to extract from the shell in large pieces and has been largely ignored. Most still come from wild trees in Missouri. Another American species, the butternut (J. cinerea), is even less known, but remarkable for its high protein content — near 30% — and esteemed by enthusiasts as among the tastiest nuts. The Japanese have an indigenous walnut, J. ailantifolia, one of whose varieties is the distinctively heart-shaped heartnut.

Characteristics
of Other Oil-Rich Seeds

Flaxseed Flaxseed comes from plants native to Eurasia, species of Linum and especially L. usitatissimum, which have been used for more than 7,000 years as a food and to make linen fiber. The small, tough, reddish-brown seed is about 35% oil and 30% protein, and has a pleasantly nutty flavor and an attractively glossy appearance. Two qualities set it apart from other edible seeds. First, its oil is over half linolenic acid, an “omega-3” fatty acid that the body can convert into the healthful long-chain fatty acids (DHA, EPA) found in seafoods (p. 183). Flax oil (also known as linseed oil, and valued in manufacturing for drying to a tough water-resistant layer) is by far the richest source of omega-3 fatty acids among plant foods. Second, flaxseed is about 30% dietary fiber, a quarter of which is a gum in the seed coat made up of long chains of various sugars. Thanks to the gum, ground flaxseed forms a thick gel when mixed with water, is an effective emulsifier and foam stabilizer, and can improve the volume of baked goods.

Poppy Seeds Poppy seeds come from a west Asian plant, Papaver somniferum, that was cultivated by the ancient Sumerians. It’s the same plant whose immature seed capsules are cut to collect the latex called opium, a mixture of morphine, heroin, codeine, and other related alkaloid drugs. The seeds are harvested from the capsules after the latex flow has stopped. They may carry traces of opiate alkaloids as well, not enough to have an effect on the body, but enough to cause positive results in drug tests after the consumption of a poppy-flavored cake or pastry.

Poppy seeds are tiny; it takes 3,300 to make a gram, 90,000 an ounce, 1–2 million a pound. The seed is 50% oil by weight. Poppy seeds sometimes have a bitter, peppery taste, the result of damage to the seeds, which mixes oil with enzymes and generates free fatty acids. The striking blue color of some poppy seeds is apparently an optical illusion. Microscopic examination demonstrates that the actual pigment layer of the seed is brown. Two layers above it, however, is a layer of cells containing tiny crystals of calcium oxalate: and the crystals act like tiny prisms, refracting light rays in such a way that blue wavelengths are selectively reflected.

Pumpkin Seeds Pumpkin seeds come from the fruits of the New World native Cucurbita pepo, are notable for being deep green with chlorophyll, and for containing no starch, as much as 50% oil, and 35% protein. Pumpkin seeds are eaten widely as a snack and in Mexico are used as a sauce thickener. There are “naked” varieties that lack the usual tough, adherent seed coat and are therefore much easier to work with.

Pumpkin seed oil is a prominent salad oil in central Europe. The oil, containing mainly polyunsaturated linoleic and monounsaturated oleic acids, is intriguingly changeable in color. Pumpkin seeds contain both yellow-orange carotenoid pigments, mainly lutein, and chlorophyll. Oil pressed from raw seeds is green; but when the seed meal is wetted and heated to increase the yield, more carotenoids are extracted than chlorophyll. The result is an oil that looks dark brown in the bottle or bowl from the combination of orange and green pigments; but in a thin layer, for example on a piece of bread dipped into the oil, there are fewer pigment molecules to absorb light, the chlorophyll dominates, and the oil becomes emerald green.

Sesame Seeds Sesame seeds are the seeds of Sesamum indicum, a plant of the central African savanna that is now mostly grown in India, China, Mexico, and the Sudan. Sesame seeds are small, with 250–300 per gram and 7,500–9,000 per ounce, come in a variety of colors, from golden to brown, violet, and black, and are about 50% oil by weight. They’re usually lightly toasted (250–300ºF/120–150ºC for 5 minutes) to develop a nutty flavor, which has some sulfur aromatics in common with roasted coffee (furfurylthiol). Sesame seeds are made into the seasoned Middle Eastern paste called tahini, are added to rice balls and made into a tofu-like cake with arrowroot in Japan, and made into a sweet paste in China, as well as decorating a variety of baked goods in Europe and the United States. Sesame oil is also extracted from toasted seeds (360–400ºF/180–200ºC for 10–30 minutes) and used as a flavoring. The oil is remarkable for its resistance to oxidation and rancidity, which results from high levels of antioxidant phenolic compounds (lignans), some vitamin E, and products of the browning reactions that occur during the more thorough toasting.

Sunflower Seeds The flower of Helianthus annuus, the only North American native to become a significant world crop, is a composite of a hundred or more small flowers, each of which produces a small fruit like the “seed” of the strawberry, a single seed contained in a thin hull. The seed is mainly storage cotyledons. The sunflower originated in the American Southwest, was domesticated in Mexico nearly 3,500 years before the arrival of European explorers, and brought to Europe around 1510 as a decorative plant. The first large crops were grown in France and Bavaria in the 18th century to produce vegetable oil. Today, the world’s leading producer by far is Russia. Improved Russian oil varieties were grown in North America during World War II, and sunflower is now one of the top annual oil crops worldwide. The eating varieties are larger than the oil types, with decoratively striped hulls that are easily removed. Sunflower seeds are especially rich in phenolic antioxidants and vitamin E.