Fermented Eggs A second kind of preserved egg, little seen in the West, is made by covering gently cracked eggs in a fermenting ma.s.s of cooked rice or other grains mixed with salt: in essence a concentrated and salty version of sake or beer. A second kind of preserved egg, little seen in the West, is made by covering gently cracked eggs in a fermenting ma.s.s of cooked rice or other grains mixed with salt: in essence a concentrated and salty version of sake or beer. Zaodan Zaodan mature in four to six months and take on the aromatic, sweet, alcoholic flavor of their surroundings. Both white and yolk coagulate and fall out of the softened sh.e.l.l. Such eggs can be eaten as is or cooked first. mature in four to six months and take on the aromatic, sweet, alcoholic flavor of their surroundings. Both white and yolk coagulate and fall out of the softened sh.e.l.l. Such eggs can be eaten as is or cooked first.

Pidan: "Thousand-Year-Old" Alkali-Cured Eggs The most famous of preserved eggs are the so-called "thousand-year-old" duck eggs, which actually have only been made for about 500 years, take between one and six months to mature, and keep for a year or so. They owe their popular name - the Chinese term is The most famous of preserved eggs are the so-called "thousand-year-old" duck eggs, which actually have only been made for about 500 years, take between one and six months to mature, and keep for a year or so. They owe their popular name - the Chinese term is pidan, pidan, or "coated eggs" - to their startlingly decrepit appearance: the sh.e.l.l encrusted with mud, the white a transparent brown jelly, and the yolk a semisolid, somber jade. The flavor too is earthy and elemental, eggy in the extreme, salty, stonily alkaline, with strong accents of sulfur and ammonia. or "coated eggs" - to their startlingly decrepit appearance: the sh.e.l.l encrusted with mud, the white a transparent brown jelly, and the yolk a semisolid, somber jade. The flavor too is earthy and elemental, eggy in the extreme, salty, stonily alkaline, with strong accents of sulfur and ammonia. Pidan Pidan are toned down by rinsing the sh.e.l.led egg and allowing it time to "breathe" before serving. They are a delicacy in China, and are usually served as an appetizer. are toned down by rinsing the sh.e.l.led egg and allowing it time to "breathe" before serving. They are a delicacy in China, and are usually served as an appetizer.

There are only two essential ingredients for making pidan, pidan, in addition to the eggs: salt, and a strongly alkaline material, which can be wood ash, lime, sodium carbonate, lye (sodium hydroxide), or some combination of these. Tea is often used for flavor, and mud to create a paste that dries to a protective crust, though the eggs can also be immersed in a water solution of the curing ingredients (this gives a faster cure but also a coa.r.s.er alkaline flavor). A mild, soft-yolked version of in addition to the eggs: salt, and a strongly alkaline material, which can be wood ash, lime, sodium carbonate, lye (sodium hydroxide), or some combination of these. Tea is often used for flavor, and mud to create a paste that dries to a protective crust, though the eggs can also be immersed in a water solution of the curing ingredients (this gives a faster cure but also a coa.r.s.er alkaline flavor). A mild, soft-yolked version of pidan pidan is sometimes made by adding some lead oxide to the cure. The lead reacts with sulfur from the egg white to form a fine black powder of lead sulfide, which blocks the sh.e.l.l pores and slows the further movement of salt and alkaline ingredients into the egg. (Lead is a potent nerve toxin, so such eggs should be avoided; look for packages clearly labeled "no lead oxide." A similar effect can be obtained by replacing lead with zinc.) is sometimes made by adding some lead oxide to the cure. The lead reacts with sulfur from the egg white to form a fine black powder of lead sulfide, which blocks the sh.e.l.l pores and slows the further movement of salt and alkaline ingredients into the egg. (Lead is a potent nerve toxin, so such eggs should be avoided; look for packages clearly labeled "no lead oxide." A similar effect can be obtained by replacing lead with zinc.) Creating Clarity, Color, and Flavor The real transforming agent in The real transforming agent in pidan pidan is the alkaline material, which gradually raises the already alkaline egg from a pH of around 9 to 12 or more. This chemical stress causes what might be thought of as an inorganic version of fermentation: that is, it denatures the egg proteins, and breaks down some of the complex, flavorless proteins and fats into simpler, highly flavorful components. The disruptively high pH forces the egg proteins to unfold, and at the same time confers on them a strongly repelling negative charge. The dissolved salt, with its positive and negative ions, moderates the repulsion enough that the fine strands of widely dispersed alb.u.men proteins are able to bond into a solid yet transparent gel. In the yolk, the same extreme conditions destroy the organized structure of the yolk spheres, and with it the usual graininess; the yolk proteins coagulate into a creamy ma.s.s. The extreme alkalinity also browns the alb.u.men by accelerating the reaction between the proteins and the trace of glucose (see p. 89), and it greens the yolk by encouraging the formation of ferrous sulfide throughout the yolk, not just at its surface (as in hard-cooked eggs; see p. 89). Finally, the alkalinity intensifies the egg's flavor by breaking down both proteins and phospholipids into hydrogen sulfide, distinctly animal fatty acids, and pungent ammonia (the fumes from a freshly opened egg will turn litmus paper blue). is the alkaline material, which gradually raises the already alkaline egg from a pH of around 9 to 12 or more. This chemical stress causes what might be thought of as an inorganic version of fermentation: that is, it denatures the egg proteins, and breaks down some of the complex, flavorless proteins and fats into simpler, highly flavorful components. The disruptively high pH forces the egg proteins to unfold, and at the same time confers on them a strongly repelling negative charge. The dissolved salt, with its positive and negative ions, moderates the repulsion enough that the fine strands of widely dispersed alb.u.men proteins are able to bond into a solid yet transparent gel. In the yolk, the same extreme conditions destroy the organized structure of the yolk spheres, and with it the usual graininess; the yolk proteins coagulate into a creamy ma.s.s. The extreme alkalinity also browns the alb.u.men by accelerating the reaction between the proteins and the trace of glucose (see p. 89), and it greens the yolk by encouraging the formation of ferrous sulfide throughout the yolk, not just at its surface (as in hard-cooked eggs; see p. 89). Finally, the alkalinity intensifies the egg's flavor by breaking down both proteins and phospholipids into hydrogen sulfide, distinctly animal fatty acids, and pungent ammonia (the fumes from a freshly opened egg will turn litmus paper blue).

Nouveaux Pidan Pidan Recently, two Taiwanese food scientists devised a method for making a striking, toned-down version of Recently, two Taiwanese food scientists devised a method for making a striking, toned-down version of pidan. pidan. They minimized the chemical stress, and thus the alteration of color and flavor, by limiting the alkaline treatment to eight days in a solution of 5% salt and 4.2% lye. Such eggs don't solidify on their own. But when the unfolding and bonding are supplemented by gentle heating at 160F/70C for 10 minutes, these eggs set to a golden yolk and a colorless, clear white! They minimized the chemical stress, and thus the alteration of color and flavor, by limiting the alkaline treatment to eight days in a solution of 5% salt and 4.2% lye. Such eggs don't solidify on their own. But when the unfolding and bonding are supplemented by gentle heating at 160F/70C for 10 minutes, these eggs set to a golden yolk and a colorless, clear white!

Pine-Blossom Eggs An especially prized variant of An especially prized variant of pidan pidan is one in which the aspic-colored white is marked throughout with tiny, pale, snowflake traceries. Such eggs are known as is one in which the aspic-colored white is marked throughout with tiny, pale, snowflake traceries. Such eggs are known as songhuadan, songhuadan, or "pine-blossom" eggs. The "blossoms" turn out to be crystals of modified amino acids, which the high alkalinity has broken off from from the alb.u.men proteins. They're thus an index of protein breakdown and flavor generation, a delicate inscription of the mineral world on the blank orb of the animal, and an example of the unexpected delight that can lie hidden in the crudest of preparations. or "pine-blossom" eggs. The "blossoms" turn out to be crystals of modified amino acids, which the high alkalinity has broken off from from the alb.u.men proteins. They're thus an index of protein breakdown and flavor generation, a delicate inscription of the mineral world on the blank orb of the animal, and an example of the unexpected delight that can lie hidden in the crudest of preparations.

Chapter 3.

Meat

Eating Animals The Essence of the Animal: Mobility from MuscleHumans as Meat EatersThe History of Meat ConsumptionWhy Do People Love Meat?

Meat and Health Meat's Ancient and Immediate Nutritional Advantages......And Modern, Long-Term DisadvantagesMeat and Food-Borne Infections"Mad Cow Disease"

Controversies in Modern Meat Production HormonesAntibioticsHumane Meat Production The Structure and Qualities of Meat Muscle Tissues and Meat TextureMuscle Fiber Types: Meat ColorMuscle Fibers, Tissues, and Meat FlavorProduction Methods and Meat Quality Meat Animals and Their Characteristics Domestic Meat AnimalsDomestic Meat BirdsGame Animals and Birds The Transformation of Muscle into Meat SlaughterRigor MortisAgingCutting and Packaging Meat Spoilage and Storage Meat SpoilageRefrigerationIrradiation Cooking Fresh Meat: The Principles Heat and Meat FlavorHeat and Meat ColorHeat and Meat TextureThe Challenge of Cooking Meat: The Right TextureMeat Doneness and Safety Cooking Fresh Meat: The Methods Modifying Texture Before and After CookingFlames, Glowing Coals, and CoilsHot Air and Walls: Oven "Roasting"Hot Metal: Frying, or SauteingHot Oil: Shallow and Deep FryingHot Water: Braising, Stewing, Poaching, SimmeringWater Vapor: SteamingMicrowave CookingAfter the Cooking: Resting, Carving, and ServingLeftovers Offal, or Organ Meats LiverFoie Gra.s.skin, Cartilage, and BonesFat Meat Mixtures SausagesPates and Terrines Preserved Meats Dried Meats: JerkySalted Meats: Hams, Bacon, Corned BeefSmoked MeatsFermented Meats: Cured SausagesConfitsCanned 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 carca.s.ses. 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, grat.i.tude, 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.

Meat Fit and Unfit for Men and G.o.dsOutside Troy, Greek priests sacrifice cattle to Apollo: first they lifted back the heads of the victims, slit their throats, skinned them and carved away the meat from the thighbones and wrapped them in fat, a double fold sliced clean and topped with strips of flesh. And the old man burned these over dried split wood and over the quarters poured out glistening wine while young men at his side held five-p.r.o.nged forks. Once they had burned the bones and tasted the organs they cut the rest into pieces, pierced them with spits, roasted them to a turn and pulled them off the fire.- Homer, Iliad, Iliad, ca. 700 ca. 700 BCE BCEFor neither is it proper that the altars of the G.o.ds should be defiled with murder, nor that food of this kind should be touched by men, as neither is it fit that men should eat one another.- Porphyry, On Abstinence, On Abstinence, ca. 300 ca. 300 CE CE 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 a.s.semblies 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) (above) and contracted and contracted (below). (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 p.r.o.ne 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 sh.e.l.lfish 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 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 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 organ meats, such innards as the liver, kidneys, intestine, and so on. 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 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 a.s.sociated with the muscle causes the protein filaments to slide past each other, and then lock together by means of cross-bridging, 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. 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. 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 gra.s.s and sc.r.a.ps into nutritious meat, but const.i.tuted 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 gra.s.ses, 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. Around the time that our ancestors domesticated animals, they also began to cultivate a number of gra.s.ses, 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.

Food Words: Meat MeatThe English word meat meat has not always meant animal flesh, and its evolution indicates a shift in the eating habits of English-speaking people. In the has not always meant animal flesh, and its evolution indicates a shift in the eating habits of English-speaking people. In the Oxford English Dictionary Oxford English Dictionary's first citation for meat, meat, from the year 900, the word meant solid food in general, in contrast to drink. A vestige of this sense survives today in the habit of referring to the meat of nuts. It wasn't until 1300 that from the year 900, the word meant solid food in general, in contrast to drink. A vestige of this sense survives today in the habit of referring to the meat of nuts. It wasn't until 1300 that meat meat was used for the flesh of animals, and not until even later that this definition displaced the earlier one as animal flesh became preeminent in the English diet, in preference if not in quant.i.ty. (The same transformation can be traced in the French word was used for the flesh of animals, and not until even later that this definition displaced the earlier one as animal flesh became preeminent in the English diet, in preference if not in quant.i.ty. (The same transformation can be traced in the French word viande. viande.) One sign of this preference is Charles Carter's 1732 Compleat City and Country Cook, Compleat City and Country Cook, which devotes 50 pages to meat dishes, 25 to poultry, and 40 to fish, but only 25 to vegetables and a handful to breads and pastries. which devotes 50 pages to meat dishes, 25 to poultry, and 40 to fish, but only 25 to vegetables and a handful to breads and pastries.

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 "sc.r.a.ping 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. 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 "sc.r.a.ping 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.

Food Words: Animals and Their MeatsAs the novelist Walter Scott and others pointed out long ago, the Norman Conquest of Britain in 1066 caused a split in the English vocabulary for common meats. The Saxons had their own Germanic names for the animals - ox, steer, cow, heifer, ox, steer, cow, heifer, and and calf calf; sheep, ram, wether, ewe, sheep, ram, wether, ewe, and and lamb; swine, hog, gilt, sow, lamb; swine, hog, gilt, sow, and and pig pig - and named their flesh by attaching "meat of" to the animal name. When French became the language of the English n.o.bility in the centuries following the Conquest, the animal names survived in the countryside, but the prepared meats were rechristened in the fashion of the court cooks: the first recipe books in English call for - and named their flesh by attaching "meat of" to the animal name. When French became the language of the English n.o.bility in the centuries following the Conquest, the animal names survived in the countryside, but the prepared meats were rechristened in the fashion of the court cooks: the first recipe books in English call for beef beef (from the French (from the French boeuf boeuf), veal veal ( (veau), mutton mutton ( (mouton), and pork pork ( (porc).

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 unsurpa.s.sed 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 a.s.sociated 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. 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. 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 quant.i.ties 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. 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 quant.i.ties 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. 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 carca.s.ses are handled less carefully than they would be by skilled butchers, and where a single infected carca.s.s 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 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 carca.s.ses are handled less carefully than they would be by skilled butchers, and where a single infected carca.s.s 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 Salmonella and and E. coli. 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 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, E. coli, and the most dangerous, is a special strain called O157:H7 that causes b.l.o.o.d.y diarrhea and sometimes kidney failure, especially in children. In the United States, about a third of people diagnosed with and the most dangerous, is a special strain called O157:H7 that causes b.l.o.o.d.y diarrhea and sometimes kidney failure, especially in children. In the United States, about a third of people diagnosed with E. coli E. coli O157:H7 need to be hospitalized, and about 5% die. O157:H7 need to be hospitalized, and about 5% die. E. coli 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 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 E. coli O157:H7 infection. Grinding mixes and spreads what may be only a small contaminated portion throughout the entire ma.s.s of meat. O157:H7 infection. Grinding mixes and spreads what may be only a small contaminated portion throughout the entire ma.s.s of meat.

Prevention Prevention of bacterial infection begins with the well warranted a.s.sumption 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. Prevention of bacterial infection begins with the well warranted a.s.sumption 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 E. coli are killed at 155F/68C, 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 140F/560C, 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 160F/70C. are killed at 155F/68C, 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 140F/560C, 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 160F/70C.

Trichinosis Trichinosis is a disease caused by infection with the cysts of a small parasitic worm, Trichinosis is a disease caused by infection with the cysts of a small parasitic worm, Trichina spiralis. Trichina spiralis. In the United States, trichinosis was long a.s.sociated 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. In the United States, trichinosis was long a.s.sociated 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 137F/58C, a medium doneness, is sufficient to kill the parasite in meat; aiming for 150F/65C gives reasonable safety margin. Trichinae can also be eliminated by frozen storage for a period of at least 20 days at or lower than 5F/15C.

"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 sc.r.a.pie, 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 sc.r.a.pie. But there's a mainly hereditary human brain disease similar to sc.r.a.pie 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 j.a.pan. 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 sc.r.a.ps 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.

Invisible AnimalsHistorian William Cronon has written eloquently about the disappearance of our food animals as the system of meat production changed in the 19th century:Formerly, a person could not easily have forgotten that pork and beef were the creation of an intricate, symbiotic partnership between animals and human beings. One was not likely to forget that pigs and cattle had died so that people might eat, for one saw them grazing in familiar pastures, and regularly visited the barnyards and butcher shops where they gave up their lives in the service of one's daily meal.... As time went on, fewer of those who ate meat could say that they had ever seen the living creature whose flesh they were chewing; fewer still could say that they had actually killed the animal themselves. In the packers' world, it was easy not to remember that eating was a moral act inextricably bound to killing.... Meat was a neatly wrapped package one bought at the market. Nature did not have much to do with it.- William Cronon, Nature's Metropolis: Chicago and the Great West, Nature's Metropolis: Chicago and the Great West, 1991 1991 Hormones The manipulation of animal hormones is an ancient technology. Farmers have castrated male animals for thousands of years to make them more docile. t.e.s.t.i.c.l.e removal not only prevents the production of s.e.x 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 c.o.c.ks. 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 quant.i.ties of the banned steroid DES, which ended up in bottled baby food and caused changes in the s.e.xual 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 j.a.pan restrict the use of antibiotics in animals.

Humane Meat Production To many people, the ma.s.s 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 s.p.a.ce, 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.

Ma.s.s 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 ma.s.s 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. 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 ma.s.s 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 across the grain, so that we can chew the grain, so that we can chew with with the grain. 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 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 s.p.a.ces 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 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. 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, 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 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 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. (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. 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. 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 b.r.e.a.s.t.s for the same reasons; the protein in chicken legs is 58% 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 ma.s.s 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 b.r.e.a.s.t.s, 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. 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 b.r.e.a.s.t.s, 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, acc.u.mulates until more oxygen arrives. This acc.u.mulation 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. 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 r