Eating Animals

The Essence of the Animal: Mobility from Muscle

Humans as Meat Eaters

The History of Meat Consumption

Why Do People Love Meat?

Meat and Health

Meat’s Ancient and Immediate Nutritional Advantages…

…And Modern, Long-Term Disadvantages

Meat and Food-Borne Infections

“Mad Cow Disease”

Controversies in Modern Meat Production

Hormones

Antibiotics

Humane Meat Production

The Structure and Qualities of Meat

Muscle Tissues and Meat Texture

Muscle Fiber Types: Meat Color

Muscle Fibers, Tissues, and Meat Flavor

Production Methods and Meat Quality

Meat Animals and Their Characteristics

Domestic Meat Animals

Domestic Meat Birds

Game Animals and Birds

The Transformation of Muscle into Meat

Slaughter

Rigor Mortis

Aging

Cutting and Packaging

Meat Spoilage and Storage

Meat Spoilage

Refrigeration

Irradiation

Cooking Fresh Meat: The Principles

Heat and Meat Flavor

Heat and Meat Color

Heat and Meat Texture

The Challenge of Cooking Meat: The Right Texture

Meat Doneness and Safety

Cooking Fresh Meat: The Methods

Modifying Texture Before and After Cooking

Flames, Glowing Coals, and Coils

Hot Air and Walls: Oven “Roasting”

Hot Metal: Frying, or Sautéing

Hot Oil: Shallow and Deep Frying

Hot Water: Braising, Stewing, Poaching, Simmering

Water Vapor: Steaming

Microwave Cooking

After the Cooking: Resting, Carving, and Serving

Leftovers

Offal, or Organ Meats

Liver

Foie Gras

Skin, Cartilage, and Bones

Fat

Meat Mixtures

Sausages

Pâtés and Terrines

Preserved Meats

Dried Meats: Jerky

Salted Meats: Hams, Bacon, Corned Beef

Smoked Meats

Fermented Meats: Cured Sausages

Confits

Canned Meats

Of all the foods that we obtain from animals and plants, meat has always been the most highly prized. The sources of that prestige lie deep in human nature. Our primate ancestors lived almost exclusively on plant foods until 2 million years ago, when the changing African climate and diminishing vegetation led them to scavenge animal carcasses. Animal flesh and fatty bone marrow are more concentrated sources of food energy and tissue-building protein than nearly any plant food. They helped feed the physical enlargement of the brain that marked the evolution of early hominids into humans. Later, meat was the food that made it possible for humans to migrate from Africa and thrive in cold regions of Europe and Asia, where plant foods were seasonally scarce or even absent. Humans became active hunters around 100,000 years ago, and it’s vividly clear from cave paintings of wild cattle and horses that they saw their prey as embodiments of strength and vitality. These same qualities came to be attributed to meat as well, and a successful hunt has long been the occasion for pride, gratitude, and celebratory feasting. Though we no longer depend on the hunt for meat, or on meat for survival, animal flesh remains the centerpiece of meals throughout much of the world.

Paradoxically, meat is also the most widely avoided of major foods. In order to eat meat, we necessarily cause the death of other creatures that feel fear and pain, and whose flesh resembles our own. Many people throughout history have found this a morally unacceptable price for our own nourishment and pleasure. The ethical argument against eating meat suggests that the same food that fueled the biological evolution of modern humans now holds us back from full humaneness. But the biological and historical influences on our eating habits have their own force. However culturally sophisticated we may be, humans are still omnivorous animals, and meat is a satisfying and nourishing food, an integral part of most food traditions.

The structure of muscle tissue and meat. A piece of meat is composed of many individual muscle cells, or fibers. The fibers are in turn filled with many fibrils, which are assemblies of actin and myosin, the proteins of motion. When a muscle contracts, the filaments of actin and myosin slide past each other and decrease the overall length of the complex.

Muscle contraction. The view through a light microscope of rabbit muscle fibers, relaxed (above) and contracted (below).

Less philosophical questions, but more immediate ones for the cook, have been raised by the changing quality of meat over the last few decades. Thanks to the industrial drive toward greater efficiency, and consumer worries about animal fats, meat has been getting younger and leaner, and therefore more prone to end up dry and flavorless. Traditional cooking methods don’t always serve modern meat well, and cooks need to know how to adjust them.

Our species eats just about everything that moves, from insects and snails to horses and whales. This chapter gives details for only the more common meats of the developed world, but the general principles apply to the flesh of all animals. Though fish and shellfish are as much flesh foods as meat and poultry, their flesh is unusual in several ways. They are the subject of chapter 4.

Eating Animals

By the word meat we mean the body tissues of animals that can be eaten as food, anything from frog legs to calf brains. We usually make a distinction between meats proper, muscle tissue whose function is to move some part of the animal, and organ meats, such innards as the liver, kidneys, intestine, and so on.

The Essence of the Animal: Mobility from Muscle

What is it that makes a creature an animal? The word comes from an Indo-European root meaning “to breathe,” to move air in and out of the body. The definitive characteristic of animals is the power to move the body and nearby parts of the world. Most of our meats are muscles, the propulsive machinery that moves an animal across a meadow, or through the sky or sea.

The job of any muscle is to shorten itself, or contract, when it receives the appropriate signal from the nervous system. A muscle is made up of long, thin cells, the muscle fibers, each of which is filled with two kinds of specialized, contractile protein filaments intertwined with each other. This packing of protein filaments is what makes meat such a rich nutritional source of protein. An electrical impulse from the nerve associated with the muscle causes the protein filaments to slide past each other, and then lock together by means of cross-bridging, or forming bonds with each other. The change in relative position of the filaments shortens the muscle cell as a whole, and the cross bridges maintain the contraction by holding the filaments in place.

Portable Energy: Fat Like any machine, the muscle protein machine requires energy to run. Almost as important to animals as their propulsive machinery is an energy supply compact enough that it doesn’t weigh them down and impede their movement. It turns out that fat packs twice as many calories into a given weight as carbohydrates do. This is why mobile animals store up energy almost exclusively in fat, and unlike stationary plants, are rich rather than starchy.

Because fat is critical to animal life, most animals are able to take advantage of abundant food by laying down large stores of fat. Many species, from insects to fish to birds to mammals, gorge themselves in preparation for migration, breeding, or surviving seasonal scarcity. Some migratory birds put on 50% of their lean weight in fat in just a few weeks, then fly 3,000 to 4,000 kilometers from the northeast United States to South America without refueling. In seasonally cold parts of the world, fattening has been part of the resonance of autumn, the time when wild game animals are at their plumpest and most appealing, and when humans practice their cultural version of fattening, the harvest and storing of crops that will see them through winter’s scarcity. Humans have long exploited the fattening ability of our meat animals by overfeeding them before slaughter, to make them more succulent and flavorful (p. 135).

Humans as Meat Eaters

Meat became a predictable part of the human diet beginning around 9,000 years ago, when early peoples in the Middle East managed to tame a handful of wild animals — first dogs, then goats and sheep, then pigs and cattle and horses — to live alongside them. Livestock not only transformed inedible grass and scraps into nutritious meat, but constituted a walking larder, a store of concentrated nourishment that could be harvested whenever it was needed. Because they were adaptable enough to submit to human control, our meat animals have flourished and now number in the billions, while many wild animals are being squeezed by the growth of cities and farmlands into ever smaller habitats, and their populations are declining.

The History
of Meat Consumption

The Scarcity of Meat in Agricultural Societies Around the time that our ancestors domesticated animals, they also began to cultivate a number of grasses, plants that grow in extensive stands and produce large numbers of nutritious seeds. This was the beginning of agriculture. With the arrival of domesticated barley and wheat, rice and maize, nomadic peoples settled down to farm the land and produce food, populations boomed — and most people ate very little meat. Grain crops are simply a far more efficient form of nourishment than animals grazing on the same land, so meat became relatively expensive, a luxury reserved for the rulers. From the prehistoric invention of agriculture to the Industrial Revolution, the great majority of people on the planet lived on cereal gruels and breads. Beginning with Europe and the Americas in the 19th century, industrialization has generally made meat less expensive and more widely available thanks to the development of managed pastures and formulated feeds, the intensive breeding of animals for efficient meat production, and improved transportation from farms to cities. But in less developed parts of the world, meat is still a luxury reserved for the wealthy few.

Abundant Meat in North America From the beginning, Americans have enjoyed an abundance of meat made possible by the size and richness of the continent. In the 19th century, as the country became urbanized and more people lived away from the farm, meats were barreled in salt to preserve them in transit and in the shops; salt pork was as much a staple food as bread (hence such phrases as “scraping the bottom of the barrel” and “pork-barrel politics”). In the 1870s a wider distribution of fresh meat, especially beef, was made possible by several advances, including the growth of the cattle industry in the West, the introduction of cattle cars on the railroads, and the development of the refrigerated railroad car by Gustavus Swift and Philip Armour.

Today, with one fifteenth of the world’s population, the United States eats one third of the world’s meat. Meat consumption on this scale is possible only in wealthy societies like our own, because animal flesh remains a much less efficient source of nourishment than plant protein. It takes much less grain to feed a person than it does to feed a steer or chicken in order to feed a person. Even today, with advanced methods of production, it takes 2 pounds of grain to get 1 pound of chicken meat, and the ratios are 4 to 1 for pork, 8 to 1 for beef. We can afford to depend on animals as a major source of food only because we have a surplus of seed proteins.

Why Do People Love Meat?

If meat eating helped our species survive and then thrive across the globe, then it’s understandable why many peoples fell into the habit, and why meat would have a significant place in human culture and tradition. But the deepest satisfaction in eating meat probably comes from instinct and biology. Before we became creatures of culture, nutritional wisdom was built into our sensory system, our taste buds, odor receptors, and brain. Our taste buds in particular are designed to help us recognize and pursue important nutrients: we have receptors for essential salts, for energy-rich sugars, for amino acids, the building blocks of proteins, for energy-bearing molecules called nucleotides. Raw meat triggers all these tastes, because muscle cells are relatively fragile, and because they’re biochemically very active. The cells in a plant leaf or seed, by contrast, are protected by tough cell walls that prevent much of their contents from being freed by chewing, and their protein and starch are locked up in inert storage granules. Meat is thus mouth-filling in a way that few plant foods are. Its rich aroma when cooked comes from the same biochemical complexity.

Meat and Health

Meat’s Ancient and Immediate Nutritional Advantages…

The meat of wild animals was by far the most concentrated natural source of protein and iron in the diet of our earliest human ancestors, and along with oily nuts, the most concentrated source of energy. (It’s also unsurpassed for several B vitamins.) Thanks to the combination of meat, calcium-rich leaf foods, and a vigorous life, the early hunter-gatherers were robust, with strong skeletons, jaws, and teeth. When agriculture and settled life developed in the Middle East beginning 10,000 years ago, human diet and activity narrowed considerably. Meats and vegetables were displaced from the diet of early farmers by easily grown starchy grains that are relatively poor in calcium, iron, and protein. With this and the higher prevalence of infectious disease caused by population growth and crowding, the rise of agriculture brought about a general decline in human stature, bone strength, and dental health.

A return to something like the robustness of the hunter-gatherers came to the industrialized world beginning late in the 19th century. This broad improvement in stature and life expectancy owed a great deal to improvements in medicine and especially public hygiene (water quality, waste treatment), but the growing nutritional contribution of meat and milk also played an essential role.

…And Modern, Long-Term Disadvantages

By the middle of the 20th century, we had a pretty good understanding of the nutritional requirements for day-to-day good health. Most people in the West had plenty of food, and life expectancy had risen to seven or eight decades. Medical research then began to concentrate on the role of nutrition in the diseases that cut the good life short, mainly heart disease and cancer. And here meat and its strong appeal turned out to have a significant disadvantage: a diet high in meat is associated with a higher risk of developing heart disease and cancer. In our postindustrial life of physical inactivity and essentially unlimited ability to indulge our taste for meat, meat’s otherwise valuable endowment of energy contributes to obesity, which increases the risk of various diseases. The saturated fats typical of meats raise blood cholesterol levels and can contribute to heart disease. And to the extent that meat displaces from our diet the vegetables and fruits that help fight heart disease and cancer (p. 255), it increases our vulnerability to both.

It’s prudent, then, to temper our species’ infatuation with meat. It helped make us what we are, but now it can help unmake us. We should eat meat in moderation, and accompany it with the vegetables and fruits that complement its nutritional strengths and limitations.

Minimizing Toxic By-Products in Cooked Meats We should also prepare meat with care. Scientists have identified three families of chemicals created during meat preparation that damage DNA and cause cancers in laboratory animals, and that may increase our risk of developing cancer of the large intestine.

Heterocyclic Amines HCAs are formed at high temperatures by the reaction of minor meat components (creatine and creatinine) with amino acids. HCA production is generally greatest at the meat surface where the temperature is highest and the meat juices collect, and on meats that are grilled, broiled, or fried well done. Oven roasting leaves relatively few HCAs on the meat but large amounts in the pan drippings. Acid marinades reduce HCA production, as does cooking gently and aiming for a rare or medium doneness. Vegetables, fruits, and acidophilus bacteria (p. 47) appear to bind HCAs in the digestive tract and prevent them from causing damage.

Polycyclic Aromatic Hydrocarbons PAHs are created when nearly any organic material, including wood and fat, is heated to the point that it begins to burn (p. 448). Cooking over a smoky wood fire therefore deposits PAHs from the wood on meat. A charcoal fire is largely smokeless, but will create PAHs from fat if the fat is allowed to fall and burn on the coals, or if the fat ignites on the meat surface itself. Small quantities of PAHs can also be formed during high-temperature frying. The PAH hazard can be minimized by grilling over wood only when it has been reduced to coals, by leaving the grill uncovered so that soot and vapors can dissipate, by avoiding fat flareups, and by eating smoked meats only rarely.

Nitrosamines Nitrosamines are formed when nitrogen-containing groups on amino acids and related compounds combine with nitrite, a chemical that has been used for millennia in salt-cured meats, and that suppresses the bacterium that causes botulism (p. 174). This reaction between amino acids and nitrites takes place both in our digestive system and in very hot frying pans. Nitrosamines are known to be powerful DNA-damaging chemicals, yet at present there’s no clear evidence that the nitrites in cured meats increase the risk of developing cancer. Still, it’s probably prudent to eat cured meats in moderation and cook them gently.

Meat and
Food-Borne Infections

Beyond the possibility that it may chip away at our longevity by contributing to heart disease and cancer, meat can also pose the much more immediate hazard of causing infection by disease microbes. This problem remains all too common.

Bacterial Infection Exactly because it is a nutritious material, meat is especially vulnerable to colonization by microbes, mainly bacteria. And because animal skins and digestive tracts are rich reservoirs of bacteria, it’s inevitable that initially clean meat surfaces will be contaminated during slaughter and the removal of skin, feathers, and innards. The problem is magnified in standard mechanized operations, where carcasses are handled less carefully than they would be by skilled butchers, and where a single infected carcass is more likely to contaminate others. Most bacteria are harmless and simply spoil the meat by consuming its nutrients and eventually generating unpleasant smells and a slimy surface. A number, however, can invade the cells of our digestive system, and produce toxins to destroy the host cells and defenses and to speed their getaway from the body. The two most prominent causes of serious meat-borne illness are Salmonella and E. coli.

Salmonella, a genus that includes more than 2,000 distinct bacterial types, causes more serious food-borne disease in Europe and North America than any other microbe, and appears to be on the rise. It’s a resilient group, adaptable to extremes of temperature, acidity, and moisture, and found in most if not all animals, including fish. In the United States it’s especially prevalent in poultry and eggs, apparently thanks to the practices of industrial-scale poultry farming: recycling animal by-products (feathers, viscera) as feed for the next generation of animals, and crowding the animals together in very close confinement, both of which favor the spread of the bacteria. Salmonella often have no obvious effect on the animal carriers, but in humans can cause diarrhea and chronic infection in other parts of the body.

Escherichia coli is the collective name for many related strains of bacteria that are normal residents of the intestines of warm-blooded animals, including humans. But several strains are aliens, and if ingested will invade the cells of the digestive tract and cause illness. The most notorious E. coli, and the most dangerous, is a special strain called O157:H7 that causes bloody diarrhea and sometimes kidney failure, especially in children. In the United States, about a third of people diagnosed with E. coli O157:H7 need to be hospitalized, and about 5% die. E. coli O157:H7 is harbored in cattle, especially calves, and other animals, but has little if any effect on them. Ground beef is by far the most common source of E. coli O157:H7 infection. Grinding mixes and spreads what may be only a small contaminated portion throughout the entire mass of meat.

Prevention Prevention of bacterial infection begins with the well warranted assumption that all meat has been contaminated with at least some disease bacteria. It requires measures to ensure that those bacteria are not spread to other foods, and are eliminated from the meats during cooking. Hands, knives, cutting boards, and countertops used to prepare meats should be cleaned with hot soapy water before being used to prepare other foods. E. coli are killed at 155ºF/68ºC, so ground meats are safest if their center gets at least this hot. Salmonella and other bacteria can multiply at significant rates between 40 and 140ºF/5–60ºC, so meats should not be left in this range for more than two hours. Buffet dishes should be kept hot, and leftovers promptly refrigerated and reheated at least to 160ºF/70ºC.

Trichinosis Trichinosis is a disease caused by infection with the cysts of a small parasitic worm, Trichina spiralis. In the United States, trichinosis was long associated with undercooked pork from pigs fed garbage that sometimes included infected rodents or other animals. Uncooked garbage was banned as pork feed in 1980, and since then the incidence of trichinosis in the United States has declined to fewer than ten cases annually. Most of these are not from pork, but from such game meats as bear, boar, and walrus.

For many years it was recommended that pork be cooked past well done to ensure the elimination of trichinae. It’s now known that a temperature of 137ºF/58ºC, a medium doneness, is sufficient to kill the parasite in meat; aiming for 150ºF/65ºC gives reasonable safety margin. Trichinae can also be eliminated by frozen storage for a period of at least 20 days at or lower than 5ºF/–15ºC.

“Mad Cow Disease”

“Mad cow disease” is the common name for bovine spongiform encephalopathy, or BSE, a disease that slowly destroys the brains of cattle. It’s an especially worrisome disease because the agent of infection is a nonliving protein particle that cannot be destroyed by cooking, and that appears to cause a similar and fatal disease in people who eat infected beef. We still have a lot to learn about it.

BSE originated in the early 1980s when cattle were fed by-products from sheep suffering from a brain disease called scrapie, whose cause appears to be a chemically stable protein aggregate called a prion. The sheep prions somehow adapted to their new host and began to cause brain disease in the cattle.

Humans are not susceptible to sheep scrapie. But there’s a mainly hereditary human brain disease similar to scrapie and caused by a similar prion; it is called Creutzfeldt-Jakob disease (CJD), typically strikes old people with loss of coordination and then dementia, and eventually kills them. In 1995 and 1996, ten relatively young Britons died from a new variant of CJD, and the prion agent found in their bodies was closely related to the BSE prion. This strongly suggests that humans can contract a devastating disease by eating meat from BSE-infected cattle. The cattle brain, spinal cord, and retina are thought to be the tissues in which prions are concentrated, but a 2004 report suggests that they may also be found in muscles and thus in common cuts of beef.

BSE appears to have been eliminated in Britain thanks to the culling of affected herds, changes in feeding, and surveillance. But diseased cattle have turned up elsewhere in Europe, as well as in the United States, Canada, and Japan. As a precautionary measure, a number of countries have suspended some traditional practices at least temporarily. These include eating flavorful meat from older animals (which are more likely to carry BSE), as well as beef brains, sweetbreads and spleen (immune-system organs), and intestines (which contain immune-system tissues). Some countries also forbid the use of “mechanically recovered meat” — tiny scraps removed from the skeleton by machine and incorporated into ground beef — from the head and spinal column. These rules will probably be modified as rapid tests for the animal disease are developed and implemented, and as we learn more about how it is transmitted to people.

To date, the known human death toll from BSE-infected beef numbers in the low hundreds, and the overall risk of contracting the prion disease from beef appears to be very small.

Controversies in Modern
Meat Production

Meat production is big business. In the United States just a few decades ago, it was second only to automobile manufacturing. Both industry and government have long underwritten research on innovative ways to control meat production and its costs. The result has been a reliable supply of relatively inexpensive meat, but also a production system increasingly distant from its origins in the family farmer’s pasture, pigsty, and chicken coop, and troubling in various ways. Many innovations involve the use of chemicals to manipulate animal metabolism. These chemicals act as drugs in the animals, and raise worries that they may influence human health as well. Other innovations involve the animals’ living conditions, which have become increasingly artificial and crowded, and their feed, which often includes reprocessed waste materials from various agricultural industries, and which contributed to the origin of mad cow disease and the persistence of salmonella in chickens. The scale and concentration of modern meat production, with hundreds of thousands of animals confined in a single facility, have caused significant water, soil, and air pollution. Enough consumers and producers have become uneasy about these developments that there is now a modest segment of the industry devoted to meats raised more traditionally, on a smaller scale, and with more attention to the quality of the animals’ life and meat.

Hormones

The manipulation of animal hormones is an ancient technology. Farmers have castrated male animals for thousands of years to make them more docile. Testicle removal not only prevents the production of sex hormones that stimulate aggressive behavior, but also turns out to favor the production of fat tissue over muscle. This is why steers and capons have long been preferred as meat animals over bulls and cocks. The modern preference for lean meat has led some producers to raise uncastrated animals, or to replace certain hormones in castrates. Several natural and synthetic hormones, including estrogen and testosterone, produce leaner, more muscular cattle more rapidly and on less feed. There is ongoing research into a variety of growth factors and other drugs that would help producers fine-tune the growth and proportions of fat to lean in cattle and other meat animals.

Currently, beef producers are allowed to treat meat cattle with six hormones in the United States, Canada, Australia, and New Zealand, but not in Europe. Hormone treatments were outlawed in the European Economic Community in 1989 in response to well-publicized abuses; a few Italian veal producers injected their calves with large quantities of the banned steroid DES, which ended up in bottled baby food and caused changes in the sexual organs of some infants. Laboratory studies indicate that meat from animals treated with allowed hormone levels contains only minute hormone residues, and that these residues are harmless when ingested by humans.

Antibiotics

Efficient industrial-scale meat production requires that large numbers of animals be raised in close confinement, a situation that favors the rapid spread of disease. In order to control animal pathogens, many producers routinely add antibiotics to their feed. This practice turns out to have the additional advantage of increasing growth rate and feed efficiency.

Antibiotic residues in meat are minute and apparently insignificant. However, there’s good evidence that the use of antibiotics in livestock has encouraged the evolution of antibiotic-resistant campylobacter and salmonella bacteria, and that these bacteria have caused illness in U.S. consumers. Because resistant bacteria are more difficult to control, Europe and Japan restrict the use of antibiotics in animals.

Humane Meat Production

To many people, the mass production of livestock is itself undesirable. In a series of legislative acts and executive orders dating back to 1978, Switzerland has mandated that producers accommodate the needs of their animals for such things as living space, access to the outdoors, and natural light, and limit the size of herds and flocks. The European Union is also adopting animal welfare guidelines for meat production, and producers in a number of countries have grouped together to establish and monitor their own voluntary guidelines.

Mass production has certainly made meat a more affordable food than it would be otherwise. But because we raise meat animals in order to eat them, it seems only just that we try to make their brief lives as satisfying as possible. It would certainly be a challenge to raise meat animals economically while taking their nature and instincts into account and allowing them the opportunity to roam, nest, and nurture their young. But it’s a challenge at least as worthy as finding a way to trim another 1% from production costs.

The Structure
and Qualities of Meat

Lean meat is made up of three basic materials: it’s about 75% water, 20% protein, and 3% fat. These materials are woven into three kinds of tissue. The main tissue is the mass of muscle cells, the long fibers that cause movement when they contract and relax. Surrounding the muscle fibers is the connective tissue, a kind of living glue that harnesses the fibers together and to the bones that they move. And interspersed among the fibers and connective tissue are groups of fat cells, which store fat as a source of energy for the muscle fibers. The qualities of meat — its texture, color, and flavor — are determined to a large extent by the arrangement and relative proportions of the muscle fibers, connective tissue, and fat tissue.

Muscle Tissues
and Meat Texture

Muscle Fibers When we look at a piece of meat, most of what we see are bundles of muscle cells, the fibers that do the moving. A single fiber is very thin, around the thickness of a human hair (a tenth to a hundredth of a millimeter in diameter), but it can be as long as the whole muscle. The muscle fibers are organized in bundles, the larger fibers that we can easily see and tease apart in well-cooked meat.

The basic texture of meat, dense and firm, comes from the mass of muscle fibers, which cooking makes denser, dryer, and tougher. And their elongated arrangement accounts for the “grain” of meat. Cut parallel to the bundles and you see them from the side, lined up like the logs of a cabin wall; cut across the bundles and you see just their ends. It’s easier to push fiber bundles apart from each other than to break the bundles themselves, so it’s easier to chew along the direction of the fibers than across them. We usually carve meat across the grain, so that we can chew with the grain.

Muscle fibers are small in diameter when the animal is young and its muscles little used. As it grows and exercises, its muscles get stronger by enlarging — not by increasing the number of fibers, but by increasing the number of contractile protein fibrils within the individual fibers. That is, the number of muscle cells stays the same, but they get thicker. The more protein fibrils there are packed together in the cells, the harder it is to cut across them. So the meat of older, well exercised animals is tougher than the meat of young animals.

Connective Tissue Connective tissue is the physical harness for all the other tissues in the body, muscle included. It connects individual cells and tissues to each other, thus organizing and coordinating their actions. Invisibly thin layers of connective tissue surround each muscle fiber and hold neighboring fibers together in bundles, then merge to form the large, silver-white sheets that organize fiber bundles into muscles, and the translucent tendons that join muscles to bones. When the fibers contract, they pull this harness of connective tissue with them, and the harness pulls the bones. The more force that a muscle exerts, the more connective tissue it needs for reinforcement, and the stronger the tissue needs to be. So as an animal’s growth and exercise bulk up the muscle fibers, they also bulk up and toughen the connective tissue.

Connective tissue includes some living cells, but consists mainly of molecules that the cells secrete into the large spaces between them. The most important of these molecules for the cook are the protein filaments that run throughout the tissue and reinforce it. One, a protein called elastin for its stretchiness, is the main component of blood vessel walls and ligaments, and is especially tough; its cross-links cannot be broken by the heat of cooking. Fortunately there isn’t much of it in most muscle tissue.

The major connective-tissue filament is the protein called collagen, which makes up about a third of all the protein in the animal body, and is concentrated in skin, tendons, and bones. The name comes from the Greek for “glue producing,” because when it’s heated in water, solid, tough collagen partly dissolves into sticky gelatin (p. 597). So unlike the muscle fibers, which become tougher with cooking, the connective tissue becomes softer. An animal starts out life with a large amount of collagen that’s easily dissolved into gelatin. As it grows and its muscles work, its total collagen supply declines, but the filaments that remain are more highly crosslinked and less soluble in hot water. This is why cooked veal seems gelatinous and tender, mature beef less gelatinous and tougher.

Fat Tissue Fat tissue is a special form of connective tissue, one in which some of the cells take on the role of storing energy. Animals form fat tissue in three different parts of the body: just under the skin, where it can provide insulation as well as energy; in well-defined deposits in the body cavity, often around the kidneys, intestine, and heart; and in the connective tissue separating muscles and the bundles within muscles. The term “marbling” is used to describe the pattern of white splotches in the red matrix of muscle.

Tissues and Textures The texture of tender meat is as distinctive and satisfying as its flavor: a “meaty” food is something you can sink your teeth into, dense and substantial, initially resistant to the tooth but soon giving way as it liberates its flavor. Toughness is a resistance to chewing that persists long enough to become unpleasant. Toughness can come from the muscle fibers, the connective tissue surrounding them, and from the lack of marbling fat.

Generally, the toughness of a cut of meat is determined by where it comes from in the animal’s body, and by the animal’s age and activity. Get down on all fours and “graze,” and you’ll notice that the neck, shoulders, chest, and front limbs all work hard, while the back is more relaxed. Shoulders and legs are used continually in walking and standing, and include a number of different muscles and their connective-tissue sheaths. They are therefore relatively tough. The tenderloin is appropriately named because it is a single muscle with little internal connective tissue that runs along the back and gets little action; it’s tender. Bird legs are tougher than breasts for the same reasons; the protein in chicken legs is 5–8% collagen compared to 2% in the breast. Younger animals — veal, lamb, pork, and chicken all come from younger animals than beef does — have tenderer muscle fibers because they are smaller and less exercised; and the collagen in their connective tissue is more rapidly and completely converted to gelatin than older, more cross-linked collagen.

Connective tissue. Muscle fibers are bundled, held in place, and reinforced by sheets of connective tissue. The more connective tissue in a given piece of meat, the tougher its texture.

Fat contributes to the apparent tenderness of meat in three ways: fat cells interrupt and weaken the sheet of connective tissue and the mass of muscle fibers; fat melts when heated rather than drying out and stiffening as the fibers do; and it lubricates the tissue, helping to separate fiber from fiber. Without much fat, otherwise tender meat becomes compacted, dry, and tough. Beef shoulder muscles contain more connective tissue than the leg muscles, but they also include more fat, and therefore make more succulent dishes.

Muscle Fiber Types:
Meat Color

Why do chickens have both white and dark meat, and why do the two kinds of meat taste different? Why is veal pale and delicate, beef red and robust? The key is the muscle fiber. There are several different kinds of muscle fiber, each designed for a particular kind of work, and each with its own color and flavor.

White and Red Fibers Animals move in two basic ways. They move suddenly, rapidly, and briefly, for example when a startled pheasant explodes into the air and lands a few hundred yards away. And they move deliberately and persistently, for example when the same pheasant supports its body weight on its legs as it stands and walks; or a steer stands and chews its cud. There are two basic kinds of muscle fibers that execute these movements, the white fibers of pheasant and chicken breasts, and the red fibers of bird and steer legs. The two types differ in many biochemical details, but the most significant difference is the energy supply each uses.

White Muscle Fibers White muscle fibers specialize in exerting force rapidly and briefly. They are fueled by a small store of a carbohydrate called glycogen, which is already in the fibers, and is rapidly converted into energy by enzymes right in the cell fluids. White cells use oxygen to burn glycogen, but if necessary they can generate their energy faster than the blood can deliver oxygen. When they do so, a waste product, lactic acid, accumulates until more oxygen arrives. This accumulation of lactic acid limits the cells’ endurance, as does their limited fuel supply. This is why white cells work best in short intermittent bursts with long rest periods in between, during which the lactic acid can be removed and glycogen replaced.

Steer anatomy and cuts of beef. The shoulder, arm, and leg do most of the work of supporting the animal. They therefore contain a large proportion of reinforcing connective tissue, are tough, and best cooked thoroughly for an hour or more to dissolve the connective-tissue collagen into gelatin. The rib, short loin, and sirloin do less work, are generally the tenderest cuts, and are tender even when cooked briefly to a medium doneness.

Red Muscle Fibers Red muscle fibers are used for prolonged efforts. They are fueled primarily by fat, whose metabolism absolutely requires oxygen, and obtain both fat (in the form of fatty acids) and oxygen from the blood. Red fibers are relatively thin, so that fatty acids and oxygen can diffuse into them from the blood more easily. They also contain their own droplets of fat, and the biochemical machinery necessary to convert it into energy. This machinery includes two proteins that give red cells their color. Myoglobin, a relative of the oxygen-carrying hemoglobin that makes blood red, receives oxygen from the blood, temporarily stores it, and then passes it to the fat-oxidizing proteins. And among the fat oxidizers are the cytochromes, which like hemoglobin and myoglobin contain iron and are dark in color. The greater the oxygen needs of the fiber, and the more it’s exercised, the more myoglobin and cytochromes it will contain. The muscles of young cattle and sheep are typically 0.3% myoglobin by weight and relatively pale, but the muscles of the constantly moving whale, which must store large amounts of oxygen during its prolonged dives, have 25 times more myoglobin in their cells, and are nearly black.

Fiber Proportions: White Meat and Dark Meat Because most animal muscles are used for both rapid and slow movements, they contain both white and red muscle fibers, as well as hybrid fibers that combine some characteristics of the other two. The proportions of the different fibers in a given muscle depend on the inherited genetic design for that muscle and the actual patterns of muscle use. Frogs and rabbits, which make quick, sporadic movements and use very few of their skeletal muscles continuously, have very pale flesh consisting mainly of white fast fibers, while the cheek muscles of ruminating, perpetually cud-chewing steers are exclusively red slow fibers. Chickens and turkeys fly only when startled, run occasionally, and mostly stand and walk; so their breast muscles consist predominantly of white fibers, while their leg muscles are on average half white fibers, half red. The breast muscles of such migratory birds as ducks and pigeons are predominantly red fibers because they’re designed to help the birds fly for hundreds of miles at a time.

Muscle Pigments The principal pigment in meat is the oxygen-storing protein myoglobin, which can assume several different forms and hues depending on its chemical environment. Myoglobin consists of two connected structures: a kind of molecular cage with an iron atom at the center, and an attached protein. When the iron is holding onto a molecule of oxygen, myoglobin is bright red. When the oxygen is pulled away by enzymes in the muscle cell that need it, the myoglobin becomes dark purple. (Similarly, hemoglobin is red in our arteries because it’s fresh from our lungs, and blue in our veins because it has unloaded oxygen into our cells.) And when oxygen manages to rob the iron atom of an electron and then escape, the iron atom loses its ability to hold oxygen at all, has to settle for a water molecule, and the myoglobin becomes brown.

White and red muscle fibers. Fast muscle cells are thicker than slow cells, contain little oxygen-storing myoglobin pigment and few fat-burning mitochondria. The thinness of slow, red muscle fibers speeds the diffusion of oxygen from the external blood supply to the center of the fibers.

Each of these myoglobins — the red, the purple, and the brown — is present in red meat. Their relative proportions, and so the meat’s appearance, are determined by several factors: the amount of oxygen available, the activity of oxygen-consuming enzymes in the muscle tissue, and the activity of enzymes that can resupply brown myoglobin with an electron, which turns it purple again. Acidity, temperature, and salt concentration also matter; if any is high enough to destabilize the attached protein, myoglobin is more likely to lose an electron and turn brown. Generally, fresh red meat with active enzyme systems will be red on the surface, where oxygen is abundant, and purple inside, where the little oxygen that diffuses through is consumed by enzymes. When we cut into raw meat or into a rare steak, the initially purple interior quickly “blooms,” or reddens, thanks to its direct exposure to the air. Similarly, vacuum-packed meat appears purple due to the absence of oxygen, and reddens only when removed from the package.

The pink color of salt-cured meats comes from yet another alteration of the myoglobin molecule (p. 148).

Muscle Fibers, Tissues,
and Meat Flavor

The main source of meat’s great appeal is its flavor. Meat flavor has two aspects: what might be called generic meatiness, and the special aromas that characterize meats from different animals. Meatiness is largely provided by the muscle fibers, character aromas by the fat tissue.

Muscle Fibers: The Flavor of Action Meaty flavor is a combination of mouth-filling taste sensations and a characteristic, rich aroma. Both arise from the proteins and energy-generating machinery of the muscle fibers — after they have been broken down into small pieces by the muscle’s enzymes and by the heat of cooking. Some of these pieces — single amino acids and short chains of them, sugars, fatty acids, nucleotides, and salts — are what stimulate the tongue with sweet, sour, salty, and savory sensations. And when they’re heated, they react with each other to form hundreds of aromatic compounds. In general, well-exercised muscle with a high proportion of red fibers (chicken leg, beef) makes more flavorful meat than less exercised, predominantly white-fibered muscle (chicken breast, veal). Red fibers contain more materials with the potential for generating flavor, in particular fat droplets and fat-like components of the membranes that house the cytochromes. They also have more substances that help break these flavor precursors down into flavorful pieces, including the iron atoms in myoglobin and cytochromes, the oxygen that those molecules hold, and the enzymes that convert fat into energy and recycle the cell’s proteins.

Meat pigments. Left: The heme group, a carbon-ring structure at the center of both hemoglobin and myoglobin molecules that holds oxygen for use by the animal body’s cells. The protein portion of these molecules, the globin, is a long, folded chain of amino acids, and is not shown here. Right: Three different states of the heme group in uncooked meat. In the absence of oxygen, myoglobin is purple. Myoglobin that has bound a molecule of oxygen gas is red. When little oxygen is available for some time, the iron atom in the heme group is readily oxidized — robbed of an electron — and the resulting pigment molecule is brownish (right).

This connection between exercise and flavor has been known for a very long time. Nearly 200 years ago, Brillat-Savarin made fun of “those gastronomes who pretend to have discovered the special flavor of the leg upon which a sleeping pheasant rests his weight.”

Fat: The Flavor of the Tribe The machinery of the red or white muscle fiber is much the same no matter what the animal, because it has the specific job of generating movement. Fat cells, on the other hand, are essentially storage tissue, and any sort of fat-soluble material can end up in them. So the contents of fat tissue vary from species to species, and are also affected by the animal’s diet and resident gastrointestinal microbes. It’s largely the contents of the fat tissue that give beef, lamb, pork, and chicken their distinctive flavors, which are composites of many different kinds of aroma molecules. The fat molecules themselves can be transformed by heat and oxygen into molecules that smell fruity or floral, nutty or “green,” with the relative proportions depending on the nature of the fat. Compounds from forage plants contribute to the “cowy” flavor of beef. Lambs and sheep store a number of unusual molecules, including branched-chain fatty acids that their livers produce from a compound generated by the microbes in their rumen, and thymol, the same molecule that gives thyme its aroma. The “piggy” flavor of pork and gamy flavor of duck are thought to come from intestinal microbes and their fat-soluble products of amino-acid metabolism, while the “sweetness” in pork aroma comes from a kind of molecule that also gives coconut and peach their character (lactones).

Grass versus Grain In general, grass or forage feeding results in stronger-tasting meat than grain or concentrate feeding, thanks to the plants’ high content of various odorous substances, reactive polyunsaturated fatty acids, and chlorophyll, which rumen microbes convert into chemicals called terpenes, relatives of the aroma compounds in many herbs and spices (p. 273). Another important contributor to grass-fed flavor is skatole, which on its own smells like manure! The deep “beefy” flavor of beef, however, is more prominent in grain-fed animals. And the flavor carried in fat gets stronger as animals get older, as more of the flavor compounds are put into storage. This is why lamb is generally more popular than mutton from mature sheep.

Production Methods
and Meat Quality

Full-flavored meat comes from animals that have led a full life. However, exercise and age also increase muscle fiber diameter and the cross-linking of connective tissue: so a full life also means tougher meat. In centuries past, most people ate mature, tough, strongly flavored meat, and developed long-cooked recipes to soften it. Today, most of us eat young, tender, mild meat that is at its best quickly cooked; long-cooking often dries it out. This shift in meat quality has resulted from a shift in the way the animals are raised.

Rural and Urban Styles of Meat There are two traditional, indeed ancient ways of obtaining meat from animals, and they produce meats of distinctive qualities.

One method is to raise animals primarily for their value as living companions — oxen and horses for their work in the fields, laying hens for their eggs, cows and sheep and goats for their milk and for wool — and turn them into meat only when they are no longer productive. In this system, slaughtering animals for meat is the last use of a resource that is more valuable when alive. The meat comes from mature animals, and is therefore well exercised and relatively tough, lean but flavorful. This method was by far the most common one from prehistoric times until the 19th century.

The second way of obtaining meat from animals is to raise the animals exclusively for that purpose. This means feeding the animals well, sparing them unnecessary exercise, and slaughtering them young to obtain tender, mild, fatty flesh. This method also goes back to prehistory, when it was applied to pigs and to the otherwise useless male offspring of hens and dairy animals. With the rise of cities, meat animals were confined and fattened exclusively for the urban elite who could afford such a luxury, an art represented in Egyptian murals and described by Roman writers.

For many centuries, rural and urban meats coexisted, and inspired the development of two distinct styles of meat preparation: roasting for the tender, fattened meats of the wealthy, and stewing for the tough, lean meats of the peasants.

The Rural Style Disappears With the Industrial Revolution, draft animals were slowly replaced by machines. City populations and the middle class grew, and along with them the demand for meat, which encouraged the rise of large-scale specialized meat production. In 1927 the U.S. Department of Agriculture enshrined the identification of quality with urban-style fattiness when it based its beef grading system on the amount of “marbling” fat deposited within the muscles (see box). Meat from mature animals began to disappear in North America, and ever more efficient industrial production took the urban style to new extremes.

Mass Production Favors Immaturity Today nearly all meat comes from animals raised exclusively for that purpose. Mass production methods are dictated by a simple economic imperative: the meat should be produced at minimum cost, which generally means in the shortest possible time. Animals are now confined to minimize the expenditure of feed on unnecessary movement, and they’re slaughtered before they reach adulthood, when the growth of their muscles slows down. Rapid, confined growth favors the production of white muscle fibers, so modern meats are relatively pale. They’re also tender, because the animals get little exercise, because rapid growth means that their connective-tissue collagen is continuously taken apart and rebuilt and develops fewer strong cross-links, and because rapid growth means high levels of the protein-breaking enzymes that tenderize meat during aging (p. 143). But many meat lovers feel that meat has gotten less flavorful in recent decades. Life intensifies flavor, and modern meat animals are living less and less.

Changing Tastes for Fat: The Modern Style In the early 1960s, American consumers began to abandon well marbled beef and pork for less fatty cuts and for lean poultry. Since marbling develops only after the animals’ rapid muscle growth slows, the meat industry was happy to minimize fattening and improve its production efficiency. Consumer and producer preferences for lean beef led the USDA to reduce its marbling requirements for the top grades in 1965 and 1975.

The modern style of meat, then, combines elements of the traditional styles: young like the city meats, lean like the country meats, and therefore both mild and easily dried out during cooking. Cooks now face the challenge of adapting hearty country traditions to these finicky ingredients.

Quality Production: A French Example There have been small but significant exceptions to this general trend toward producing meat as cheaply as possible. In the 1960s, the French poultry industry found that many consumers were dissatisfied with the standard chicken’s bland flavor and tendency to shrink and fall off the bone when cooked. Some producers then developed a production scheme guided by considerations of quality as well as efficiency. The result was the popular label rouge, or “red label,” which identifies chickens that have been produced according to specific standards: they are slow-growing varieties, fed primarily on grain rather than artificially concentrated feeds, raised in flocks of moderate size and with access to the outdoors, and slaughtered at 80 or more days of age rather than 40 to 50. Red-label chickens are leaner and more muscular than their standard industrial equivalent, lose a third less of their moisture during cooking, are firmer in texture, and have a more pronounced flavor. Similar quality-based meat production schemes exist today in a number of countries.

So economic forces have conspired to make mild, tender meat the modern norm, but small producers of more mature, flavorful meats, sometimes from rare “heirloom” breeds, are finding their own profitable market among consumers willing to pay a premium for quality.

Meat Animals and
Their Characteristics

Each of the animals that we raise for food has its own biological nature, and its own history of being shaped by humans to meet their changing needs and tastes. This section sketches the distinctive qualities of our more common meats, and the main styles in which they’re now produced.

Domestic Meat Animals

Cattle Cattle are descendents of the wild ox or aurochs, Bos primigenius, which browsed and grazed in forests and plains all across temperate Eurasia. Cattle are our largest meat animals and take the longest to reach adulthood, about two years, so their meat is relatively dark and flavorful. Breeders began to develop specialized meat animals in the 18th century. Britain produced the compact, fat-carcassed English Hereford and Shorthorn and Scots Angus, while continental meat breeds remained closer to the rangy, lean draft type; these include the French Charolais and Limousin, and the Italian Chianina, which is probably the largest breed in the world (4,000-pound bulls, double the size of the English breeds).

American Beef The United States developed a uniform national style when federal grading standards for beef were introduced in 1927 (see box, p. 136), with the highest “Prime” grade reserved for young, fine-textured meat with abundant marbling. Purebred Angus and Hereford beef were the model for three decades. The shift in consumer preference to lower-fat meat brought revisions of the USDA grades to allow leaner meat to qualify for the Prime and Choice grades (see box below). Nowadays, U.S. beef comes mainly from steers (males castrated as calves) and heifers (females that have never calved) between 15 and 24 months old, and fed on grain for the last four to eight months. Recent years have brought a new interest in beef from cattle raised exclusively on grass, which is leaner and stronger in flavor (p. 134) than mainstream beef.

European Beef Other beef-loving countries raise their cattle differently and have produced distinctive beefs. Italy prefers young meat from animals slaughtered at 16–18 months. Until the advent of BSE, much French and British beef came from dairy stock several years old. According to a standard French handbook, Technologie Culinaire (1995), the meat of an animal less than two years old is “completely insipid,” while meat “at the summit of quality” comes from a steer three to four years old. But because the risk of an animal having BSE rises as it grows older, a number of countries now require that meat cattle be slaughtered at less than three years of age. In 2004, most French and British beef came from animals no older than 30 months.

Japanese Beef Japan prizes its shimofuri, or highly marbled beef, of which the best known comes from the Kobe region. Steers of the native Wagyu draft breed are slaughtered at 24–30 months. High-quality heifers (and some steers) are identified and then fattened for a further year or more on grain. (Currently Japan tests all meat cattle for BSE.) This process produces beef that is mature, flavorful, tender, and very rich, with as much as 40% marbling fat. The best cuts are usually sliced very thin, in 1.5–2 mm sheets, and simmered in broth for a few seconds in the one-pot dishes called sukiyaki and shabu shabu.

Veal Veal is the meat of young male offspring of dairy cows. Veal has traditionally been valued for being as different as possible from beef: pale, delicate in flavor, with a softer fat, and succulently tender thanks to its soluble collagen, which readily dissolves into gelatin when cooked. Calf flesh becomes more like beef with every day of ordinary life, so most veal calves aren’t allowed an ordinary life: they’re confined so that exercise won’t darken, flavor, and toughen their muscles, and fed a low-iron diet with no grass to minimize the production of myoglobin pigment and prevent rumen development (p. 13), which would saturate and thus harden the fat. In the United States, veal generally comes from confined animals fed a soy or milk formula and slaughtered between 5 and 16 weeks old, when they weigh 150 to 500 lb/70–230 kg. “Bob” or “drop” veal comes from unconfined, milk-fed animals three weeks old or less. “Free-range” and “grain-fed” veal have become increasingly common as more humane alternatives, but are more like beef in the color and flavor of their meat.

Sheep Along with goats, sheep were probably the first animals to be domesticated after the dog, thanks to their small size, around a tenth that of cattle, and their herding instinct. Most European breeds of sheep are specialized for milk or wool; there are relatively few specialized meat breeds.

Lamb and Mutton Lamb and sheep meat is finer grained and more tender than beef, but well endowed with red myoglobin and with flavor, including a characteristic odor (p. 134) that becomes more pronounced with age. Pasture-feeding, particularly on alfalfa and clover, increases the levels of a compound called skatole, which also contributes a barnyardy element to pork flavor, while lambs finished on grain for a month before slaughter are milder. In the United States, lambs are sold in a range of ages and weights, from 1 to 12 months and 20–100 lb/9–45 kg, under a variety of names, including “milk” and “hothouse” lamb for younger animals, “spring” and “Easter” lamb for the rest (though production is no longer truly seasonal). New Zealand lamb is pasture-fed but slaughtered at four months, younger than most American lamb, and remains mild. In France, older lambs (mouton) and young female sheep (brebis) are aged for a week or more after slaughter, and develop an especially rich flavor.

Pigs Pigs are descendents of the Eurasian wild boar, Sus scrofa. If beef has been the most esteemed of meats in Europe and the Americas, pork has fed far more people, both there and in the rest of the world: in China the word for “pork” is also the generic word for “meat.” The pig has the virtues of being a relatively small, voracious omnivore that grows rapidly and bears large litters. Its indiscriminate appetite means that it can turn otherwise useless scraps into meat, but that meat can harbor and transmit parasites from infected animals and their remains (see p. 126 on trichinosis). Perhaps in part for this reason, and because pigs are difficult to herd and will devour field crops, pork eating has been forbidden among various peoples, notably Middle Eastern Jews and Muslims.

There are several specialized styles of pigs, including lard breeds, bacon breeds, and meat breeds, some large-boned and massive, some (Iberian and Basque ham pigs) relatively lean, slow-growing, small and dark-fleshed, much like their wild south-Europe ancestors. Today most of the specialized breeds have been displaced by the fast-growing descendents of a few European bacon and meat breeds.

Pork Like modern beef, modern pork comes from much younger and leaner animals than was true a century ago. Pigs are typically slaughtered at six months and 220 lb/100 kg, just as they reach sexual maturity, when the connective tissue is still relatively soluble and the meat tender. Individual cuts of American and European pork generally contain half to a fifth of the fat they did in 1980. Pork is a pale meat because the pig uses its muscles more intermittently than do cattle and sheep, and therefore has a lower proportion of red muscle fibers (around 15%). Some small Chinese and European breeds have darker and significantly more flavorful flesh.

Domestic Meat Birds

Chickens Chickens are descendents of the aggressive, pugnacious red jungle fowl of northern India and southern China. Gallus gallus is a member of the pheasant family or Phasianidae, a large, originally Eurasian group of birds that tend to colonize open forest or the edge between field and wood. Chickens seem to have been domesticated in the vicinity of Thailand before 7500 BCE, and arrived in the Mediterranean around 500 BCE. In the West, they were largely unpampered farmyard scavengers until the 19th-century importation of large Chinese birds created a veritable chicken-breeding craze in Europe and North America. Mass production began in the 20th century, when much of the genetic diversity in meat chickens evaporated in favor of a fast-growing cross between the broad-breasted Cornish (developed in Britain from Asian fighting stock) and the U.S. White Plymouth Rock.

Chicken Styles The modern chicken is a product of the drive to breed fast-growing animals and raise them as rapidly and on as little feed as possible. It’s an impressive feat of agricultural engineering to produce a 4-pound bird on 8 pounds of feed in six weeks! Because such a bird grows very fast and lives very little, its meat is fairly bland, and that of the younger “game hen” or “poussin” even more so.

Largely in reaction to the image of industrial chicken, so-called “free range” chickens are now sold in the United States, but the term only means that the birds have access to an outdoor pen. “Roasting” chickens and capons (castrated males) are raised to double or more the age of the standard broiler, are heavier, and so have given their leg muscles more exercise; the capon may also be more succulent thanks to the infiltration of marbling fat.

Turkeys Turkeys are also members of the sedentary pheasant family. Meleagris gallopavo descended from ancestors that once ranged through North America and Asia. The modern colossal turkey dates from 1927–1930, when a breeder in British Columbia developed a 40 lb/18 kg bird with oversized flight and thigh muscles, and breeders in the U.S. northwest used his stock to perfect the Broad-Breasted Bronze. The little-used breast muscle is tender, mild, and lean; the leg muscles that support the breast are well-exercised, dark, and flavorful.

Today, industrial facilities produce 14–20 lb/6–9 kg birds year-round in 12–18 weeks; some small American farms extend the period to 24 weeks, while the name-controlled French Bresse turkey is raised for 32 weeks or more, confined and fattened for the last several weeks on corn and milk.

Ducks and Squab Ducks and squab are notable for having dark, flavorful breast meat, abundantly endowed with myoglobin-rich red muscle fibers, thanks to their ability to fly hundreds of miles in a day with few stops. The most common breeds of duck in China, much of Europe, and the United States are descendents of the wild green-headed mallard, Anas platyrhynchos, an aquatic migratory bird that puts on as much as a third of its carcass weight in fat for fuel and under-skin insulation. Ducks are eaten at two ages: in the egg as 15–20-day embryos (the Philippine boiled delicacy balut), and at 6 to 16 weeks. The Muscovy duck is an entirely different bird: Cairina moschata, the greater wood duck, which is native to the west coast of Central and northern South America, differs in three important ways from mallard varieties: it lays down about a third less body fat, grows significantly larger, and has a more pronounced flavor.

Squab, dove, and pigeon are various names for the European rock dove, Columba livia, a species that includes the common city pigeon; “squab” means a bird young enough that it has never flown. Its flying muscles weigh five times as much as its leg muscles. Today, domestic squab are raised for four weeks and slaughtered at about 1 lb/450 g, just before they’re mature enough to fly.

Game Animals and Birds

Wild animals — sometimes called game or venison — have always been especially prized in the autumn, when they fatten themselves for the coming winter. While the autumn game season is still celebrated in many European restaurants with wild duck, hare, pheasant, partridge, deer, and boar, in the United States wild meats are banned from commerce (only inspected meat can be sold legally, and hunted meat is not inspected). Most “game” meats available to the U.S. consumer these days come from animals raised on farms and ranches. They’re perhaps better described as “semi-domestic” meats. Some of these animals have been raised in captivity since Roman times, but haven’t been as intensively bred as the domesticated animals, and so are still much like their wild counterparts.

Today Americans are buying more venison (various species of deer and antelope), buffalo, and other game meats thanks to their distinctive flavors and leanness. The very low fat content of game meat causes it to conduct heat and cook faster than standard meats, and to dry out more easily. Cooks often shield it from direct oven heat by “barding” it with a sheet of fat or fatty bacon, and baste it during cooking, which cools the meat surface by evaporation and slows the movement of heat into the meat (p. 158).

Gaminess True wild game has the appeal of rich, variable flavor, thanks to its mature age, free exercise, and mixed diet. Carried to excess, this interesting wild flavor becomes “gamy.” In the time of Brillat-Savarin, game was typically allowed to hang for days or weeks until it began to rot. This treatment was called mortification or faisandage (after the pheasant, faisan), and had two purposes: it tenderized the meat, and further heightened its “wild” flavor. Gamy game is no longer the style. Modern farmed animals are often relatively sedentary, eat a uniform diet, and are slaughtered before they reach sexual maturity, so they’re usually milder in flavor and more tender than their wild counterparts. Since distinctive meat flavors reside in the fat, they can be minimized by careful trimming.

The Transformation
of Muscle into Meat

The first step in meat production is to raise a healthy animal. The second step is to transform the living animal into useful portions of its flesh. The ways in which this transformation occurs affect the quality of the meat, and can explain why the same cut of meat from the same store can be moist and tender one week and dry and tough the next. So it’s useful to know what goes on in the slaughterhouse and packing plant.

Slaughter

The Importance of Avoiding Stress By a fortunate coincidence, the methods of slaughter that result in good-quality meat are also the most humane. It has been recognized for centuries that stress just before an animal’s death — whether physical work, hunger, duress in transport, fighting, or simple fear — has an adverse effect on meat quality. When an animal is killed, its muscle cells continue to live for some time and consume their energy supply (glycogen, an animal version of starch). In the process they accumulate lactic acid, which reduces enzyme activity, slows microbial spoilage, and causes some fluid loss, which makes the meat seem moist. Stress depletes the muscles of their energy supply before slaughter, so that after slaughter they accumulate less lactic acid and produce readily spoiled “dark, firm, dry” or “dark-cutting” meat, a condition first described in the 18th century. So it pays to treat animals well. In November 1979, the New York Times reported that a Finnish slaughterhouse had evicted a group of young musicians from a nearby building because their practice sessions were resulting in dark-cutting meat.

Procedures Meat animals are generally slaughtered as untraumatically as possible. Each animal is stunned, usually with a blow or electrical discharge to the head, and then is hung up by the legs. One or two of the major blood vessels in the neck are cut, and the animal bleeds to death while unconscious. As much blood as possible (about half) is removed to decrease the risk of spoilage. (Rarely, as in the French Rouen duck, blood is retained in the animal to deepen the meat’s flavor and color.) After bleeding, cattle and lamb heads are removed, the hides stripped off, the carcasses cut open, and the inner organs removed. Pig carcasses remain intact until they have been scalded, scraped and singed to remove bristles; the head and innards are then removed, but the skin is left in place.

Chickens, turkeys, and other fowl must be plucked. The slaughtered birds are usually immersed in a bath of hot water to loosen the feathers, plucked by machine, and cooled in a cold-water bath or cold-air blast. Prolonged water-chilling can add a significant amount of water to the carcass: U.S. regulations allow 5–12% of chicken weight to be absorbed water, or several ounces in a 4-pound bird. By contrast, air-chilling, which is standard in much of Europe and Scandinavia, actually removes water, so that the flesh becomes more concentrated and the skin will brown more readily.

Kosher and halal meats are processed according to Jewish and Muslim religious laws respectively, which among other things require a brief period of salting. These practices don’t allow meat birds to be scalded before plucking, so their skin is often torn. The plucked carcasses are then salted for 30–60 minutes and briefly rinsed in cold water; like air-chilled birds, they absorb little if any extraneous moisture. Salting makes meat fats more prone to oxidation and the development of off flavors, so kosher and halal meats don’t keep as long as conventionally processed meats.

Rigor Mortis

The Importance of Timing, Posture, and Temperature For a brief period after the animal’s death its muscles are relaxed, and if immediately cut and cooked will make especially tender meat. Soon, however, the muscles clench in the condition called rigor mortis (“stiffness of death”). If cooked in this state, they make very tough meat. Rigor sets in (after about 2.5 hours in the steer, 1 hour or less in lamb, pork, and chicken) when the muscle fibers run out of energy, their control systems fail and trigger a contracting movement of the protein filaments, and the filaments lock in place. Carcasses are hung up in such a way that most of their muscles are stretched by gravity, so that the protein filaments can’t contract and overlap very much; otherwise the filaments bunch up and bond very tightly and the meat becomes exceptionally tough. Eventually, protein-digesting enzymes within the muscle fibers begin to eat away the framework that holds the actin and myosin filaments in place. The filaments are still locked together, and the muscles cannot be stretched, but the overall muscle structure weakens, and the meat texture softens. This is the beginning of the aging process. It becomes noticeable after about a day in beef, after several hours in pork and chicken.

The inevitable toughening during rigor mortis can be worsened by poor temperature control, and may be the source of excessive toughness in retail meats.

Aging

Like cheese and wine, meat benefits from a certain period of aging, or slow chemical change, during which it gets progressively more flavorful. Meat also becomes more tender. In the 19th century, beef and mutton joints would be kept at room temperature for days or weeks, until the outside was literally rotten. The French called this mortification, and the great chef Antonin Carême said that it should proceed “as far as possible.” The modern taste is for somewhat less mortified flesh! In fact most meat in the United States is aged only incidentally, during the few days it takes to be shipped from packing plant to market. This is enough for chicken, which benefits from a day or two of aging, and for pork and lamb, which benefit from a week. (The unsaturated fats of pork and poultry go rancid relatively quickly.) But the flavor and texture of beef keeps improving for up to a month, especially when whole, unwrapped sides are dry-aged at 34–38ºF/1–3ºC and at a relative humidity of 70–80%. The cool temperature limits the growth of microbes, while the moderate humidity causes the meat to lose moisture gradually, and thus become denser and more concentrated.

Muscle Enzymes Generate Flavor… The aging of meat is mainly the work of the muscle enzymes. Once the animal is slaughtered and the control systems in its cells stop functioning, the enzymes begin attacking other cell molecules indiscriminately, turning large flavorless molecules into smaller, flavorful fragments. They break proteins into savory amino acids; glycogen into sweet glucose; the energy currency ATP into savory IMP (inosine monophosphate); fats and fat-like membrane molecules into aromatic fatty acids. All of these breakdown products contribute to the intensely meaty, nutty flavor of aged meat. During cooking, the same products also react with each other to form new molecules that enrich the aroma further.

…And Diminish Toughness Uncontrolled enzyme activity also tenderizes meat. Enzymes called calpains mainly weaken the supporting proteins that hold the contracting filaments in place. Others called cathepsins break apart a variety of proteins, including the contracting filaments and the supporting molecules. The cathepsins also weaken the collagen in connective tissue, by breaking some of the strong cross-links between mature collagen fibers. This has two important effects: it causes more collagen to dissolve into gelatin during cooking, thus making the meat more tender and succulent; and it reduces the squeezing pressure that the connective tissue exerts during heating (p. 150), which means that the meat loses less moisture during cooking.

Enzyme activity depends on temperature. The calpains begin to denature and lose activity around 105ºF/40ºC, the cathepsins around 122ºF/50ºC. But below this critical range, the higher the temperature, the faster the enzymes work. Some accelerated “aging” can take place during cooking. If meat is quickly seared or blanched in boiling water to eliminate microbes on its surface, and then heated up slowly during the cooking — for example, by braising or roasting in a slow oven — then the aging enzymes within the meat can be very active for several hours before they denature. Large 50 lb/23 kg slow-roasted “steamship” rounds of beef spend 10 hours or more rising to 120–130ºF/50–55ºC, and come out more tender than small portions of the same cut cooked quickly.

Aging Meat in Plastic and in the Kitchen Despite the contribution that aging can make to meat quality, the modern meat industry generally avoids it, since it means tying up its assets in cold storage and losing about 20% of the meat’s original weight to evaporation and laborious trimming of the dried, rancid, sometimes moldy surface. Most meat is now butchered into retail cuts at the packing plant shortly after slaughter, wrapped in plastic, and shipped to market immediately, with an average of 4 to 10 days between slaughter and sale. Such meat is sometimes wet-aged, or kept in its plastic wrap for some days or weeks, where it’s shielded from oxygen and retains moisture while its enzymes work. Wet-aged meat can develop some of the flavor and tenderness of dry-aged meat, but not the same concentration of flavor.

Cooks can age meat in the kitchen. Simply buying meat several days before it’s needed will mean some informal aging in the refrigerator, where it can be kept tightly wrapped, or uncovered to allow some evaporation and concentration. (Loose or no wrapping may cause dry spots, the absorption of undesirable odors, and the necessity of some trimming; this works best with large roasts, not steaks and chops.) And as we’ve seen, slow cooking gives the aging enzymes a chance to do in a few hours what would otherwise take weeks.

Cutting and Packaging

In the traditional butchering practice that prevailed until the late 20th century but is now rare, animal carcasses are divided at the slaughterhouse into large pieces — halves or quarters — which are then delivered to retail butchers, who break them down into roasts, steaks, chops, and the other standard cuts. The meat might not be wrapped at all until sale, and then only loosely in “butcher’s paper.” Such meat is continuously exposed to the air, so it tends to be fully oxygenated and red, and it slowly dries out, which concentrates its flavor at the same time that it leaves some surface areas discolored and off-flavored and in need of trimming.

The modern tendency in butchering is to break meat down into the retail cuts at the packing house, vacuum-wrap them in plastic precisely to avoid exposure to the air, and deliver these prepackaged cuts to the supermarket. Vacuum-packed meat has the economic advantage of assembly-line efficiency, and keeps for weeks (as much as 12 for beef, 6 to 8 for pork and lamb) without any weight loss due to drying or trimming. Once repackaged, meat has a display-case life of a few days.

Carefully handled, well packaged meat will be firm to the touch, moist and even-colored in appearance, and mild and fresh in smell.

Meat Spoilage and Storage

Fresh meat is an unstable food. Once a living muscle has been transformed into a piece of meat it begins to change, both chemically and biologically. The changes that we associate with aging — the generation of flavor and tenderness by enzymes throughout the meat — are desirable. But the changes that take place at the meat surface are generally undesirable. Oxygen in the air and energetic rays of light generate off-flavors and dull color. And meat is a nourishing food for microbes as well as for humans. Given the chance, bacteria will feast on meat surfaces and multiply. The result is both unappetizing and unsafe, since some microbial digesters of dead flesh can also poison or invade the living.

Meat Spoilage

Fat Oxidation and Rancidity The most important chemical damage suffered by meats is the breakdown of their fats by both oxygen and light into small, odorous fragments that define the smell of rancidity. Rancid fat won’t necessarily make us sick, but it’s unpleasant, so its development limits how long we can age and store meat. Unsaturated fats are most susceptible to rancidity, which means that fish, poultry, and game birds go bad most quickly. Beef has the most saturated and stable of all meat fats, and keeps the longest.

Fat oxidation in meats can’t be prevented, but it can be delayed by careful handling. Wrap raw meat tightly in oxygen-impermeable plastic wrap (saran, or polyvinylidene chloride; polyethylene is permeable), overwrap it with foil or paper to keep it in the dark, store it in the coldest corner of the refrigerator or freezer, and use it as soon as possible. When cooking with ground meat, grind the meat fresh, just before cooking, since dividing the meat into many small pieces exposes a very large surface area to the air. The development of rancidity in cooked meats can be delayed by minimizing the use of salt, which encourages fat oxidation, and by using ingredients with antioxidant activity: for example the Mediterranean herbs, especially rosemary (p. 395). Browning the meat surface in a hot pan also generates antioxidant molecules that can delay fat oxidation.

Spoilage by Bacteria and Molds The intact muscles of healthy livestock are generally free of microbes. The bacteria and molds that spoil meat are introduced during processing, usually from the animal’s hide or the packing-plant machinery. Poultry and fish are especially prone to spoilage because they’re sold with their skin intact, and many bacteria persist despite washing. Most of these are harmless but unpleasant. Bacteria and molds break down cells at the meat surface and digest proteins and amino acids into molecules that smell fishy, skunky, and like rotten eggs. Spoiled meat smells more disgusting than other rotten foods exactly because it contains the proteins that generate these stinky compounds.

Refrigeration

In the developed world, the most common domestic method for preserving meat is simply to keep it cool. Refrigeration has two great advantages: it requires little or no preparation time, and it leaves the meat relatively unchanged from its fresh state. Cooling meat extends its useful life because both bacteria and meat enzymes become less active as the temperature drops. Even so, spoilage does continue. Meats keep best at temperatures approaching or below the freezing point, 32ºF/0ºC.

Freezing Freezing greatly extends the storage life of meat and other foods because it halts all biological processes. Life requires liquid water, and freezing immobilizes the food’s liquid water in solid crystals of ice. Well-frozen meat will keep for millennia, as has been demonstrated by the discovery of mammoth flesh frozen 15,000 years ago in the ice of northern Siberia. It’s best to keep meat as cold as possible. The usual recommendation for home freezers is 0ºF/–18ºC (many operate at 10–15ºF/–12 to –9ºC).

Freezing will preserve meat indefinitely from biological decay. However, it’s a drastic physical treatment that inevitably causes damage to the muscle tissue, and therefore diminishes meat quality in several ways.

Cell Damage and Fluid Loss As raw meat freezes, the growing crystals protrude into the soft cell membranes and puncture them. When the meat is thawed, the ice crystals melt and unplug the holes they’ve made in the muscle cells, and the tissue as a whole readily leaks a fluid rich in salts, vitamins, proteins, and pigments. Then when the meat is cooked, it loses more fluid than usual (p. 150), and more readily ends up dry, dense, and tough. Cooked meat suffers less from freezing because its tissue has already been damaged and lost fluid when it was heated.

Cell damage and fluid loss are minimized by freezing the meat as rapidly as possible and keeping it as cold as possible. The faster the meat moisture freezes, the smaller the crystals that it forms, and the less they protrude into the cell membranes; and the colder the meat is kept, the less enlargement of existing crystals will occur. Freezing can be accelerated by setting the freezer at its coldest temperature, dividing the meat into small pieces, and leaving it unwrapped until after it has solidified (wrapping acts as insulation and can double the freezing time).

Fat Oxidation and Rancidity In addition to inflicting physical damage, freezing causes chemical changes that limit the storage life of frozen meats. When ice crystals form and remove liquid water from the muscle fluids, the increasing concentration of salts and trace metals promotes the oxidation of unsaturated fats, and rancid flavors accumulate. This inexorable process means that quality declines noticeably for fresh fish and poultry after only a few months in the freezer, for pork after about six months, for lamb and veal after about nine months, and for beef after about a year. The flavors of ground meats, cured meats, and cooked meats deteriorate even faster.

Freezer Burn A last side effect of freezing is freezer burn, that familiar brownish-white discoloration of the meat surface that develops after some weeks or months of storage. This is caused by water “sublimation” — the equivalent of evaporation at below-freezing temperatures — from ice crystals at the meat surface into the dry freezer air. The departure of the water leaves tiny cavities in the meat surface which scatter light and so appear white. The meat surface is now in effect a thin layer of freeze-dried meat where oxidation of fat and pigment is accelerated, so texture, flavor, and color all suffer.

Freezer burn can be minimized by covering the meat as tightly as possible with water-impermeable plastic wrap.

Thawing Meats Frozen meats are usually thawed before cooking. The simplest method — leaving the meat on the kitchen counter — is neither safe nor efficient. The surface can rise to microbe-friendly temperatures long before the interior thaws, and air transfers heat to the meat very slowly, at about one-twentieth the rate that water does. A much faster and safer method is to immerse the wrapped meat in a bath of ice water, which keeps the surface safely cold, but still transfers heat into the meat efficiently. If the piece of meat is too large for a water bath, or isn’t needed right away, then it’s also safe to thaw it in the refrigerator. But cold air is an especially inefficient purveyor of warmth, so it can take days for a large roast to thaw.

Cooking Unthawed Meats Frozen meats can be cooked without thawing them first, particularly with relatively slow methods such as oven roasting, which give the heat time to penetrate to the center without drastically overcooking the outer portions of the meat. Cooking times are generally 30–50% longer than for fresh cuts.

Irradiation

Because ionizing radiation (p. 782) damages delicate biological machinery like DNA and proteins, it kills spoilage and disease microbes in food, thus extending its shelf life and making it safer to eat. Tests have shown that low doses of radiation can kill most microbes and more than double the shelf life of carefully wrapped refrigerated meats. There is, however, a characteristic radiation flavor, described as metallic, sulfurous, and goaty, which may be barely noticeable or unpleasantly strong.

Beginning in 1985, the U.S. Food and Drug Administration has approved irradiation to control a number of pathogens in meat: first trichinosis in pork, then salmonella in chickens, and E. coli in beef. A treatment like irradiation is an especially valuable form of insurance for the mass production of ground meats, in which a single infected carcass can contaminate thousands of pounds of meat, and affect thousands of consumers. But its use remains limited due to consumer wariness. Decades of testing indicate that irradiated meat is safe to eat. But one other objection is quite reasonable. If meat has been contaminated with enough fecal matter to cause infection with E. coli, then irradiation will kill the bacteria and leave the meat edible for three months. However, it will still be adulterated meat. Many consumers set a higher standard than the absence of living pathogens and months of shelf life for the food from which they take daily nourishment and pleasure. People who care about food quality will seek out meat produced locally, carefully, and recently, and for enjoyment within a few days, when it’s at its best.

Cooking Fresh Meat:
The Principles

We cook meat for four basic reasons: to make it safe to eat, easier to chew and to digest (denatured proteins are more vulnerable to our digestive enzymes), and to make it more flavorful. The issue of safety is detailed beginning on p. 124. Here I’ll describe the physical and chemical transformations of meat during cooking, their effects on flavor and texture, and the challenge of cooking meat well. These changes are summarized in the box on p. 152.

Heat and Meat Flavor

Raw meat is tasty rather than flavorful. It provides salts, savory amino acids, and a slight acidity to the tongue, but offers little in the way of aroma. Cooking intensifies the taste of meat and creates its aroma. Simple physical damage to the muscle fibers causes them to release more of their fluids and therefore more stimulating substances for the tongue. This fluid release is at its maximum when meat is only lightly cooked, or done “rare.” As the temperature increases and the meat dries out, physical change gives way to chemical change, and to the development of aroma as cell molecules break apart and recombine with each other to form new molecules that not only smell meaty, but also fruity and floral, nutty and grassy (esters, ketones, aldehydes).

Surface Browning at High Temperatures If fresh meat never gets hotter than the boiling point of water, then its flavor is largely determined by the breakdown products of proteins and fats. However, roasted, broiled, and fried meats develop a crust that is much more intensely flavored, because the meat surface dries out and gets hot enough to trigger the Maillard or browning reactions (p. 778). Meat aromas generated in the browning reactions are generally small rings of carbon atoms with additions of nitrogen, oxygen, and sulfur. Many of these have a generic “roasted” character, but some are grassy, floral, oniony or spicy, and earthy. Several hundred aromatic compounds have been found in roasted meats!

Heat and Meat Color

The appearance of meat changes in two different ways during cooking. Initially it’s somewhat translucent because its cells are filled with a relatively loose meshwork of proteins suspended in water. When heated to about 120ºF/50ºC, it develops a white opacity as heat-sensitive myosin denatures and coagulates into clumps large enough to scatter light. This change causes red meat color to lighten from red to pink, long before the red pigments themselves are affected. Then, around 140ºF/60ºC, red myoglobin begins to denature into a tan-colored version called hemichrome. As this change proceeds, meat color shifts from pink to brown-gray.

The denaturation of myoglobin parallels the denaturation of fiber proteins, and this makes it possible to judge the doneness of fresh meat by color. Little-cooked meat and its juices are red, moderately cooked meat and its juices are pink, thoroughly cooked meat is brown-gray and its juices clear. (Intact red myoglobin can escape in the meat juices; denatured brown myoglobin has bonded to other coagulated proteins in the cells and stays there.) However, there are a number of oddities about myoglobin that can lead to misleading redness or pinkness even in well-cooked meat (see box). And it’s also possible for undercooked meat to look brown and well-done, if its myoglobin has already been denatured by prolonged exposure to light or to freezing temperatures. If it’s essential that meat be cooked to microbe-destroying temperatures, then the cook should use an accurate thermometer to confirm that it has reached a minimum of 160ºF/70ºC. Meat color can be misleading.

The pigments in cooked and cured meats. Left to right: In raw meat, the oxygen-carrying myoglobin is red; in cooked meat, the oxidized, denatured form of myoglobin is brown; in meats cured with nitrite, including corned beef and ham, the myoglobin assumes a stable pink form (NO is nitric oxide, a product of nitrite); and in uncured meats cooked in a charcoal grill or gas oven, traces of carbon monoxide (CO) accumulate and produce another stable pink form.

Heat and Meat Texture

The texture of a food is created by its physical structure: the way it feels to the touch, the balance of solid and liquid components, and the ease or difficulty with which our teeth break it down into manageable pieces. The key textural components in meat are its moisture, around 75% of its weight, and the fiber proteins and connective tissue that either contain and confine that moisture, or release it.

Raw and Cooked Textures The texture of raw meat is a kind of slick, resistant mushiness. The meat is chewy yet soft, so that chewing compresses it instead of cutting through it. And its moisture manifests itself in slipperiness; chewing doesn’t manage to liberate much juice.

Heat changes meat texture drastically. As it cooks, meat develops a firmness and resilience that make it easier to chew. It begins to leak fluid, and becomes juicy. With longer cooking, the juices dry up, and resilience gives way to a dry stiffness. And when the cooking goes on for hours, the fiber bundles fray away from each other, and even tough meat begins to fall apart. All of these textures are stages in the denaturation of the fiber and connective-tissue proteins.

Early Juiciness: Fibers Coagulate One of the two major contracting filaments, the protein myosin, begins to coagulate at about 120ºF/50ºC; this lends each cell some solidity and the meat some firmness. As the myosin molecules bond to each other, they squeeze out some of the water molecules that had separated them. This water collects around the solidifying protein core, and is actively squeezed out of the cell by its thin, elastic sheath of connective tissue. In intact muscles, juices break through weak spots in the fiber sheaths. In chops and steaks, which are thin slices of whole muscles, it also escapes out the cut ends of the fibers. Meat served at this stage, the equivalent of rare, is firm and juicy.

Final Juiciness: Collagen Shrinks As the meat’s temperature rises to 140ºF/60ºC, more of the proteins inside its cells coagulate and the cells become more segregated into a solid core of coagulated protein and a surrounding tube of liquid: so the meat gets progressively firmer and moister. Then between 140 and 150ºF/60–65ºC, the meat suddenly releases lots of juice, shrinks noticeably, and becomes chewier. These changes are caused by the denaturing of collagen in the cells’ connective-tissue sheaths, which shrink and exert new pressure on the fluid-filled cells inside them. The fluid flows copiously, the piece of meat loses a sixth or more of its volume, and its protein fibers become more densely packed and so harder to cut through. Meat served in this temperature range, the equivalent of medium-rare, is changing from juicy to dry.

Falling-Apart Tenderness: Collagen Becomes Gelatin If the cooking continues, the meat will get progressively dryer, more compacted, and stiff. Then around 160ºF/70ºC, connective-tissue collagen begins to dissolve into gelatin. With time, the connective tissue softens to a jelly-like consistency, and the muscle fibers that it had held tightly together are more easily pushed apart. The fibers are still stiff and dry, but they no longer form a monolithic mass, so the meat seems more tender. And the gelatin provides a succulence of its own. This is the delightful texture of slow-cooked meats, long braises, and stews and barbecues.

How cooking forces moisture from meat. Water molecules are bound up in the protein fibrils that fill each muscle cell. As the meat is heated, the proteins coagulate, the fibrils squeeze out some of the water they had contained and shrink. The thin elastic sheet of connective tissue around each muscle cell then squeezes the unbound water out the cut ends of the cells.

The Challenge of Cooking
Meat: The Right Texture

Generally, we like meat to be tender and juicy rather than tough and dry. The ideal method for cooking meat would therefore minimize moisture loss and compacting of the meat fibers, while maximizing the conversion of tough connective-tissue collagen to fluid gelatin. Unfortunately, these two aims contradict each other. Minimizing fiber firming and moisture loss means cooking meat quickly to no hotter than 130–140ºF/55–60ºC. But turning collagen to gelatin requires prolonged cooking at 160ºF/70ºC and above. So there is no ideal cooking method for all meats. The method must be tailored to the meat’s toughness. Tender cuts are best heated rapidly and just to the point that their juices are in full flow. Grilling, frying, and roasting are the usual fast methods. Tough cuts are best heated for a prolonged period at temperatures approaching the boil, usually by stewing, braising, or slow-roasting.

It’s Easy to Overcook Tender Meat Cooking tender meat to perfection — so that its internal temperature is just what we want — is a real challenge. Imagine that we grill a thick steak just to medium rare, 140ºF/60ºC, at the center. Its surface will have dried out enough to get hotter than the boiling point, and in between the center and surface, the meat temperature spans the range between 140ºF/60°C — medium rare — and 212ºF/100°C — cooked dry. In fact the bulk of the meat is overcooked. And it only takes a minute or two to overshoot medium rare at the center and dry out the whole steak, because meat is cooked but juicy in only a narrow temperature range, just 30ºF/15ºC. When we grill or fry an inch-thick steak or chop, the rate of temperature increase at the center can exceed 10ºF/5ºC per minute.

Solutions: Two-Stage Cooking, Insulation, Anticipation There are several ways to give the cook a larger window of time for stopping the cooking, and to obtain meat that is more evenly done.

The most common method is to divide the cooking into two stages, an initial high-temperature surface browning, and a subsequent cooking through at a much lower temperature. The low cooking temperature means a smaller temperature difference between center and surface, so that more of the meat is within a few degrees of the center temperature. It also means that the meat cooks more slowly, with a larger window of time during which the interior is properly done.

Another trick is to cover the meat surface with another food, such as strips of fat or bacon, batters and breadings, pastry and bread dough. These materials insulate the meat surface from direct cooking heat and slow the heat penetration.