Ch.9: Seeds: Grains, Legumes, and Nuts

Chapter 9 of the book "On Food and Cooking: The Science and Lore of the Kitchen" by Harold McGee (1984) The Composition and Qualities of Seeds Handling and Preparing Seeds The Grains, or Cereals Legumes: Beans and Peas Nuts and Other Oil-Rich Seeds

302 flashcards · Other · by lakesare

Part of Public › Books › On Food and Cooking (Harold McGee) · 16 courses

1. [Seeds as Food] What three parts does every seed consist of?

   A baby plant (embryo), a food supply, and a protective coat. The food supply feeds germination and early growth.The coat separates the embryo from the surrounding soil and shields it against mechanical injury, microbes and animals.

2. [Seeds as Food] Where do cereal grains store their food supply, compared with beans and nuts?

   Grains: in a separate tissue (the endosperm). Beans and nuts: in the embryo's thick first leaves. These first two leaves are the cotyledons; in beans and most nuts they are unusually thick and massive. Oat kernel (endosperm), lentils and hazelnut (cotyledons); the embryo is marked in each.

3. [Seeds as Food] What did some of the earliest known writing and arithmetic (at least 5,000 years old) record?

   Accounting of grain and livestock. Grain farming required planning sowings, distributing harvests, anticipating seasons and keeping records.

4. [Seeds as Food] What share of the world's dietary protein do grains and legumes provide together?

   More than two-thirds. Grains also provide most of the calories for much of the world, especially in Asia and Africa. Homer called wheat and barley "the marrow of men's bones."

5. [Seeds as Food] To which plant family do the cereals belong?

   The grass family (Gramineae). "Cereal" comes from Ceres, the Roman goddess of agriculture, whose name goes back to a root ker, "to grow" (also behind "create", "increase", "crescent"). "Cereal" can mean the plant, its seeds (the grains), or foods made from them, as in "breakfast cereals".

6. [Seeds as Food] Which traits of the grasses made them ideal for agriculture?

   They grow fast, in dense stands, and make many small seeds that are easy to gather. Grasses live a season or two, and their dense stands crowd out competitors.Grasses rely on large numbers of seeds rather than chemical defenses for some offspring to survive.

7. [Seeds as Food] Why are legume seeds especially rich in protein?

   Bacteria in their roots supply them with nitrogen taken from the air. Protein is rich in nitrogen. The legumes and the bacteria live in symbiosis.Legumes (bean family, Leguminosae) bear pods containing several seeds.

8. [Seeds as Food] Why have farmers alternated legumes with other crops since at least the Roman era?

   Thanks to their nitrogen-fixing root bacteria, legumes enrich the soil with nitrogen compounds.

9. [Seeds as Food] What is thought to have driven the great diversity of beans and peas?

   Pressure from seed-eating insects. The large seeds attract animals, so legumes camouflage them with colored coats and protect them with several biochemical defenses.

10. [Seeds as Food] Why are nuts large seeds?

    To attract animals that bury them, and to feed a slow-growing seedling in shade. Buried nuts that the animals forget germinate.Nuts come from several plant families; they are generally large seeds in hard shells, borne on long-lived trees.

11. [Seeds as Food] In what form do most nuts store their energy, unlike grains and legumes?

    As oil rather than starch: a more compact, concentrated form.

12. [Seeds as Food] Why are nuts much less important in the human diet than grains and legumes?

    Nut trees take years to bear, and yield less per acre than grains and legumes.

13. [Seeds as Food] Which two nuts are major staple foods, unlike most nuts?

    The coconut and the peanut. The peanut is really a legume with an unusually oily, tender seed, and it can be grown quickly in huge numbers.

14. [Seeds and Health] Why did beriberi spread in 19th-century rice-eating Asia?

    Milling machines removed the rice bran, and with it the rice's thiamin (vitamin B1). The mostly vegetarian diet could not make up the loss; meat and fish are rich in thiamin.

15. [Seeds and Health] Why did pellagra strike poor people in Europe and the southern US who adopted corn as a staple?

    They took up corn without its traditional cooking in alkaline water, which makes corn's niacin available to the body. Studying beriberi and pellagra is how the missing vitamins behind these two diseases were found, in the early 1900s.

16. [Seeds and Health] Whole grains are linked with lower risk of cancer, heart disease and diabetes. Where in the grain are the probably helpful chemicals?

    In the outer layers, not in the starchy inner storage tissue. So refined grains lack them. The same holds for legumes and nuts.

17. [Seeds and Health] Which kinds of possibly health-promoting substances do whole seeds provide?

    Vitamins Including antioxidant vitamin E and its relatives, the tocotrienols. Soluble fiber Indigestible but soluble carbohydrates: slow digestion, moderate blood sugar and insulin, lower cholesterol, and feed beneficial intestinal bacteria. Insoluble fiber Speeds food through the gut and reduces absorption of carcinogens. Phenolic and other defensive compounds Some are antioxidants; some resemble human hormones and may restrain cell growth and so cancer.

18. [Seeds and Health] Which defensive chemicals in legumes can cause malnourishment?

    Lectins and protease inhibitors. Ordinary cooking inactivates them.

19. [Seeds and Health] What problem can the fava bean cause?

    Serious anemia in susceptible people, caused by relatives of amino acids in the bean. Both the bean and the susceptibility are relatively rare.

20. [Seeds and Health] What is a true food allergy?

    The immune system wrongly treats a food component as an infection, and its defense harms the body. About 2% of US adults and up to 8% of young children have one; food allergies cause around 200 US deaths a year.

21. [Seeds and Health] Which seeds are among the most common food allergens?

    Peanuts, soybeans and tree nuts. Tiny amounts of nut protein are enough to cause a reaction, even the traces sometimes found in mechanically pressed nut oils.

22. [Seeds and Health] Does cooking make allergenic seeds such as peanuts safer for allergic people?

    No: cooking does not make the seed proteins less allergenic.

23. [Seeds and Health] What happens in celiac disease (gluten-sensitive enteropathy, sprue)?

    The immune system reacts to gliadin, a wheat protein, and attacks the gut's absorbing cells. Gliadin proteins occur in wheat, barley and rye, possibly oats.The result is serious malnourishment. The disease is lifelong; the remedy is strict avoidance of gluten.

24. [Seeds and Health] Which grains and seeds contain no gliadin proteins and so are safe in celiac disease?

    Corn, rice, amaranth, buckwheat, millet, quinoa, sorghum and teff.

25. [Seeds and Health] About how much water do dry seeds contain?

    About 10% of their weight, so they keep well without special treatment. Freshly boiled or roasted seeds rarely carry food-poisoning bacteria, but moist grain and bean dishes favor bacteria as they cool: refrigerate leftovers promptly and reheat them to the boil.

26. [Seeds and Health] What can contaminate even dry grains and nuts with dangerous toxins?

    Molds, which grow with little moisture; some make toxins that can cause cancer. Example: Aspergillus species make aflatoxin, Fusarium moniliforme makes fumonisin.Any sign of mold on grains or nuts means throwing them away.

27. [The Composition and Qualities of Seeds] What is the outer protective coat of a cereal grain called?

    The bran. In legumes and nuts it is called the seed coat. It is a tough, fibrous layer rich in phenolic compounds (anthocyanin pigments, astringent tannins), and it slows the entry of water during cooking.

28. [The Composition and Qualities of Seeds] Why do cooks often remove the coat of seeds (polished rice, pearled barley, Indian dals, blanched almonds)?

    Faster cooking and a more refined appearance, texture and flavor.

29. [The Composition and Qualities of Seeds] Why does the germ (embryo) of a grain matter for flavor?

    It holds much of the grain's oil and enzymes, which produce both good cooked aromas and bad stale ones. The embryo of legumes and nuts matters little in cooking.

30. [The Composition and Qualities of Seeds] What do the cells of a seed's storage tissue contain?

    Particles of concentrated protein, granules of starch, and sometimes droplets of oil. In barley, oats and rye the cell walls also hold non-starch storage carbohydrates that, like starch, absorb water in cooking.

31. [The Composition and Qualities of Seeds] What happens when a hulled grain and a skinned bean are each boiled in plenty of water?

    The grain keeps its shape and some firmness; the bean quickly falls apart into a puree. Beans stay intact only when cooked in their seed coats. Nut cells, filled with liquid oil rather than solid starch, are more fragile still.

32. [The Composition and Qualities of Seeds] What happens to the proteins of beans and of grains when cooked in salted water?

    Bean proteins dissolve into the moisture and cooking liquid; grain proteins don't dissolve but clump together. Bean proteins are mostly the kinds that dissolve in water or salty water; grain proteins are mostly kinds that dissolve only in acid or alcohol. The clumped grain proteins form a sticky complex with the starch, part of why cooked wheat, rice, corn and barley are chewy.

33. [The Composition and Qualities of Seeds] How do the two kinds of starch molecule, amylose and amylopectin, differ?

    Amylose is a long, mostly straight chain; amylopectin is much bigger and bushy, with many branches. Both are made of glucose: amylose about 1,000 units, amylopectin 5,000 to 20,000 units with hundreds of short branches.So amylose settles easily into compact, orderly, tightly bonded clusters; bushy amylopectin does not.

34. [The Composition and Qualities of Seeds] Roughly what fraction of the starch is amylose in these seeds?

    Legumes 30% or more. Wheat, barley, maize, long-grain rice About 20%. Short-grain rice About 15%. Sticky rice Almost none: nearly pure amylopectin.

35. [The Composition and Qualities of Seeds] What is starch gelation?

    The swelling and softening of starch granules in hot water, as water molecules move in and separate the starch molecules. It happens at roughly 60 to 70°C/140 to 160°F, depending on the seed. Left: raw granule. Center: gelation in hot water. Right: retrogradation on cooling.It is often called "gelatinization", though starch has nothing to do with gelatin.

36. [The Composition and Qualities of Seeds] Why does long-grain rice need more cooking water than short-grain rice?

    It has more amylose, whose tight clusters need more water to come apart. Amylose clusters also need higher temperature and more time.

37. [The Composition and Qualities of Seeds] When cooked starch cools, its molecules re-form clusters and the granules firm up again. This is called retrogradation.

    Amylose rebonds within a few hours; bushy amylopectin takes a day or more and forms looser, weaker clusters.

38. [The Composition and Qualities of Seeds] Why does long-grain rice turn inedibly hard overnight in the fridge, while short-grain rice stays fairly soft?

    Long-grain rice is high in amylose, which retrogrades fast and firmly; short-grain rice is low in amylose. Remedy: reheat to regelate the starch.

39. [The Composition and Qualities of Seeds] Why do reheated grains never get quite as soft as when first cooked?

    During retrogradation amylose forms some crystalline regions that resist breaking even at the boil. These act as reinforcing junctions in the starch network.

40. [The Composition and Qualities of Seeds] What useful effects does retrograded starch have?

    It strengthens foods, and it resists digestion. Bread puddings, starch noodles, parboiled rice and breakfast cereals keep their shape thanks to retrograded starch.In the body it slows the rise in blood sugar and feeds desirable bacteria in the large intestine.

41. [The Composition and Qualities of Seeds] What is a seed oil body?

    A tiny oil droplet coated with phospholipids (lecithin relatives) and proteins called oleosins, which keep the droplets from merging. Oil bodies resemble the fat globules of milk in size and structure, so nuts become creamy rather than greasy in the mouth, and oily seeds can be made into "milks" (almond, soy).

42. [The Composition and Qualities of Seeds] What contributes most to the flavor of grains, legumes and nuts?

    Fragments of unsaturated fatty acids from the oils and cell membranes. Their aromas: green, fatty, oily, floral, mushroomy. Beans are rich in green and mushroom notes; dry-heated nuts add roasted browning aromas.

43. [The Composition and Qualities of Seeds] Why do whole grains taste stronger than refined ones?

    The bran layers hold much of the seed's oil and enzymes, plus phenolic compounds that add vanilla and toasted notes.

44. [Handling and Preparing Seeds] How should whole seeds be stored?

    Dry, cool and dark; then they keep for months. Moisture lets microbes grow; damage, heat and light speed the oxidation of the seed oils, which gives rancid aromas and bitter tastes.

45. [Handling and Preparing Seeds] Why do sprouted wheat and barley taste sweet?

    Their enzymes break stored starch down into sugars for the growing embryo.

46. [Handling and Preparing Seeds] How does the nutritional value of sprouts compare with seeds and vegetables?

    In between: more vitamin C and fewer calories than seeds; more protein, B vitamins and iron than most vegetables. Example: protein about 5% in sprouts versus about 2% in most vegetables.

47. [Handling and Preparing Seeds] Why can nuts be eaten raw while dry grains and legumes need cooking in water?

    Nuts have tender cell walls and liquid oil in their cells; grains and legumes are hard, with solid starch.

48. [Handling and Preparing Seeds] What does hot water do to dry grains and legumes?

    It softens the cell walls, swells the starch, and moistens the proteins. Hot water dissolves strengthening carbohydrates from the cell walls, gelates the starch, and dissolves or moistens the proteins.This exposes the nutrients to our digestive enzymes, so cooked seeds are more nutritious.

49. [Handling and Preparing Seeds] Why can presoaking seeds cut their cooking time by half or more?

    Most of the cooking time is spent waiting for water to reach the center. Heat penetrates seeds faster than water does.Likewise, seeds milled free of their coat or into small pieces cook much faster: the coat slows water entry.

50. [Handling and Preparing Seeds] How much water must most grains and legumes absorb to become soft?

    Enough to be about 60–70% water: about 1.7 times their dry weight (1.4 times their volume). Example: 100 g of dry rice absorbing 170 g of water weighs 270 g, and 170/270≈63%170/270 \approx 63\%170/270≈63% is water.Recipes use more water to allow for evaporation.

51. [Handling and Preparing Seeds] Why let cooked grains and legumes cool before handling them, if they should look intact?

    They are soft and fragile while hot and firm up as they cool.

52. [Handling and Preparing Seeds] What happens to the cooking liquid when rice or polenta is cooked in milk, or grains in meat stock?

    The grains absorb water and so concentrate the liquid: milk becomes more like cream, stock more like a reduced stock (demiglace).

53. [Handling and Preparing Seeds] Which seed protein extracts have vegetarian cooks (especially Buddhists in China and Japan) used to imitate meat?

    Wheat gluten (seitan) and soybean yuba. Seitan was first made by Chinese noodle makers around the 6th century; it was called mien chin, "muscle of flour".Both can be shaped to resemble meat fibers and fermented for savory flavors.

54. [The Grains, or Cereals] What special advantage does each major cereal have?

    Barley Especially hardy. Rye and oats Adapt to wet, cold climates. Wheat Makes an elastic paste that holds tiny bubbles: raised bread. Rice Grows in wet, hot conditions. Maize Plants and kernels far larger than other cereals'.

55. [The Grains, or Cereals] Botanically, what is a cereal grain (kernel)?

    A complete fruit, whose fruit layer (from the ovary wall) is only a thin, dry skin.

56. [The Grains, or Cereals] Which cereals have a husk (hull) that must be removed before milling?

    Barley, oats and rice. The husk forms from small, tough, leaf-like structures that fuse around the fruit. Bread and durum wheat, rye and maize are naked.

57. [The Grains, or Cereals] What is the aleurone layer of a grain?

    The outer, only living layer of the endosperm, 1 to 4 cells thick, very rich in oil, minerals, protein, vitamins, enzymes and flavor. A wheat kernel.

58. [The Grains, or Cereals] What is the endosperm of a grain made of?

    Dead storage cells: starch granules embedded in a protein matrix. "Endosperm" is Greek for "within the seed". It takes up most of the grain's volume.

59. [The Grains, or Cereals] Why do grains get less nutritious the more they are milled and polished?

    Cells toward the surface hold more protein and less starch than cells in the core.

60. [The Grains, or Cereals] What lets millers separate endosperm, germ and bran?

    Their different mechanical properties: the endosperm breaks easily, the germ is oily, the bran is leathery.

61. [The Grains, or Cereals] What do the germ and bran (with the aleurone) account for in a whole grain?

    Most of its fiber, oil and B vitamins, and about 25% of its protein.

62. [The Grains, or Cereals] Why are grains refined despite the nutritional loss?

    Refined grains are easier to cook and chew, and keep: whole-grain flour goes rancid in weeks. The oil in germ and aleurone goes rancid. Refined grains also look lighter.In industrialized countries, iron and B vitamins are usually added back to refined cereals.

63. [The Grains, or Cereals] Which common cereal grain is richest in protein and oil?

    Oats: about 17% protein and 7% oil. White rice is the poorest (7% protein, 0.5% oil); wheat has 14% protein, 2% oil. The pseudocereal amaranth has even more than oats: 18% protein, 8% oil. (Figures at about 10% moisture.)

64. [The Grains, or Cereals] What does cooking a hot cereal (oatmeal, grits, cream of wheat) do to the grain?

    It turns the grain into a soft, bland, digestible mush. Cooking softens the cell walls, gelates the starch and leaches starch molecules out.The only modern improvement is shorter cooking, by grinding finely or partly precooking.

65. [The Grains, or Cereals] How did American ready-to-eat breakfast cereals begin?

    As 19th-century health foods invented by vegetarian reformers. Among them were the Kellogg brothers and C. W. Post.Inventions included shredded wheat, wheat and corn flakes, and Grape Nuts.

66. [The Grains, or Cereals] How are the main kinds of ready-to-eat cereal made?

    Flakes Grains or grain fragments flavored, steam-cooked, cooled, rolled thin and toasted in a drum oven. Oven-puffed Cooked, partly dried and lightly rolled grains toasted in an oven up to 340°C/650°F, so the remaining water evaporates fast enough to expand them. Gun-puffed Wet whole grains heated in a sealed "gun" (260–430°C/500–800°F) to 14 atmospheres of steam pressure; sudden release expands the steam inside and puffs the grain. Extruded Dough forced at high pressure through small openings;…

67. [The Grains, or Cereals] Why is sucrose favored on ready-to-eat cereal flakes?

    It gives a frosty, glassy surface that slows milk penetration, so the flakes get soggy more slowly.

68. [The Grains, or Cereals] How many chromosome sets do the main wheats have?

    Einkorn Two (diploid): the simplest wheat. Emmer and durum Four (tetraploid): from a cross of a wild wheat with a goatgrass, less than a million years ago. Bread wheat Six (hexaploid): from a cross of a tetraploid wheat with another goatgrass, about 8,000 years ago. The extra chromosomes are thought to underlie the diversity of modern wheats, above all the elasticity of their gluten.

69. [The Grains, or Cereals] What share of the world's wheat is hexaploid bread wheat?

    About 90%. Most of the rest is durum wheat, grown mainly for pasta.

70. [The Grains, or Cereals] Why is einkorn unsuited to breadmaking?

    Its gluten is sticky and runny instead of elastic. Einkorn has 1 part elastic glutenin to 2 parts flowing gliadin; bread wheat has 1 to 1.Einkorn was probably the first wheat cultivated, about 10,000 years ago; it is high in protein and rich in yellow carotenoids.

71. [The Grains, or Cereals] Emmer wheat is now widely sold under its Italian name, farro.

    In ancient Mediterranean times emmer and durum were the two major wheats.

72. [The Grains, or Cereals] What is notable about spelt?

    Its high protein content, up to 17%. A hulled hexaploid wheat, called Dinkel in southern Germany. Grünkern ("green kernel") is spelt harvested green, dried or roasted, and milled. Spelt is often confused with emmer.

73. [The Grains, or Cereals] Why is elastic gluten good for bread but not for pasta?

    Elasticity helps dough trap gas and rise, but makes pasta dough spring back when rolled into thin sheets. Both benefit from strong, cohesive gluten. Bread wheat: strong and elastic; durum: strong, not very elastic.

74. [The Grains, or Cereals] What gives most wheat bran its reddish-brown color?

    Phenolic compounds, which browning enzymes join into large colored aggregates.

75. [The Grains, or Cereals] What are white wheats?

    Wheats with cream-colored bran, because they contain much less of the phenolics and browning enzymes that color ordinary bran. They taste less astringent and discolor less when bran is included in the flour.

76. [The Grains, or Cereals] What gives durum wheat, semolina and dry pasta their yellow color?

    The carotenoid lutein (a xanthophyll). Grain enzymes and oxygen can oxidize lutein to a colorless form. That whitening was traditionally wanted in other wheats ("wheat" comes from the same root as "white"), but not in durum.

77. [The Grains, or Cereals] What property of wheat's storage proteins made wheat the West's premier grain?

    Mixed with water, the gluten proteins bond into an elastic mass that expands to hold yeast's gas bubbles. Without wheat there would be no raised breads, cakes or pasta as we know them.

78. [The Grains, or Cereals] How is gluten separated from flour?

    Make a dough and knead it in water: starch and soluble substances wash away, leaving tough, chewy gluten. This works because gluten is cohesive and insoluble in water.

79. [The Grains, or Cereals] Why does fermented gluten make a savory condiment?

    Gluten is rich in glutamic acid, which fermentation releases: an early version of MSG.

80. [The Grains, or Cereals] Why should wheat germ and wheat bran be kept in the refrigerator?

    Their oil goes stale. Germ is 20% protein, 10% oil, 13% fiber. Bran is mainly fiber, with about 4% oil.

81. [The Grains, or Cereals] How is bulgur made?

    Whole wheat is cooked, dried, then cracked to remove bran and germ. The cooked grain is dried until glassy and moistened, then pounded or milled; endosperm chunks remain.Usually durum. The moistening toughens the bran so it comes off.The wheat counterpart of parboiled rice: nutritious, keeps indefinitely, cooks fairly quickly.

82. [The Grains, or Cereals] What made barley so widely grown in the ancient world?

    It is hardy and grows fast, from tropical plains up to the Arctic Circle. It may have been the first cereal domesticated, and was the main cereal of Babylon, Sumeria, Egypt and the Mediterranean. Roman gladiators were called hordearii, "barley eaters".

83. [The Grains, or Cereals] What is the most important form in which we consume barley?

    Malt: barley moistened and allowed to germinate until sweet with sugars, mainly for beer and spirits. In the West half the barley crop goes to animals and a third to malt.

84. [The Grains, or Cereals] Which two non-starch carbohydrates make up about 5% each of the barley grain?

    Pentosans and glucans. They give cooked barley its springy texture and make barley flour absorb twice as much water as wheat flour. Pentosans make rye sticky; glucans make oats gelatinous and lower cholesterol.

85. [The Grains, or Cereals] Why is more of the grain removed from pearled barley than from white rice?

    Barley's brittle bran breaks into small bits, so it must be ground away along with more grain. Processors also grind away the deep crease so the grains look uniform."Pot barley" loses 7–15% and keeps the germ and some bran; fine pearled barley loses about 33% (bran, germ, aleurone and subaleurone layers).

86. [The Grains, or Cereals] Which drinks' names come from barley water?

    Orgeat, horchata and tisane. Latin hordeum became French orge and orgeat (now an almond syrup), then Spanish horchata (now rice or tiger nut). Tisane comes from Latin ptisana, crushed barley or its drink.

87. [The Grains, or Cereals] How did rye become a crop?

    As a weed in wheat and barley fields that grew better than the crop in the cold Baltic region. Rye coped better with the poor acid soil and cool, moist climate there.Rye reached the Baltic around 2000 BCE and was domesticated around 1000 BCE.Its range reaches the Arctic Circle and altitudes of 4,000 m/12,000 ft.

88. [The Grains, or Cereals] What are the pentosans of rye?

    Sugar chains that soak up lots of water and make rye dough thick and sticky. They are medium-sized aggregates of sugars (arabinoxylans).They are up to 7% of rye. Thanks to them, rye flour absorbs 8 times its weight in water; wheat flour absorbs 2 times.

89. [The Grains, or Cereals] Why do rye breads stay soft and moist for weeks?

    Rye pentosans, unlike starch, don't retrograde and harden after cooking and cooling.

90. [The Grains, or Cereals] How do rye crisps help control appetite?

    Their dried pentosans swell in the stomach, giving a sense of fullness, and are digested slowly and only partly.

91. [The Grains, or Cereals] What was Saint Anthony's Fire (Holy Fire)?

    Poisoning by ergot, a fungus that grows on rye. It caused gangrene of the hands and feet, and madness. The fungus is Claviceps purpurea.Frequent from the 11th to the 16th centuries; the cool, moist climate that suits rye also suits ergot.

92. [The Grains, or Cereals] What connects ergot with LSD?

    Ergot's toxins are built on lysergic acid, the core of LSD. LSD is lysergic acid diethylamide.Some ergot alkaloids stimulate the uterus, some are hallucinogens, some constrict blood vessels (causing gangrene, but medically useful).

93. [The Grains, or Cereals] What did Samuel Johnson's Dictionary (1755) say about oats?

    "A grain, which in England is generally given to horses, but in Scotland supports the people." Oats do best in a wet climate: they need more moisture than any cereal but rice. Today 95% of oats are fed to animals.

94. [The Grains, or Cereals] Why do oats go rancid easily?

    Oats have 2 to 5 times as much fat as wheat, plus a lot of a fat-splitting enzyme. The fat is mainly in the bran and endosperm, not the germ. A heat treatment that inactivates the enzyme keeps stored oats from spoiling.

95. [The Grains, or Cereals] Why can't oats be made into light raised breads?

    Like barley, oats have no gluten-forming proteins.

96. [The Grains, or Cereals] What gives cooked oatmeal its smooth, thick consistency?

    Beta-glucans: indigestible carbohydrates that absorb and hold water. They also keep baked goods tender and moist. They lie mainly in the outer endosperm just under the aleurone layer, so oat bran is especially rich in them.

97. [The Grains, or Cereals] Which carbohydrates of oats help lower blood cholesterol?

    Beta-glucans.

98. [The Grains, or Cereals] Why are oats lightly "roasted" at low temperature before further processing?

    To develop flavor and inactivate the fat-splitting enzyme. It also denatures the storage proteins, so the grain holds together better when cooked.

99. [The Grains, or Cereals] How do steel-cut, rolled, quick and instant oats differ?

    Only in shape and thickness, hence cooking speed; nutritionally they are the same. Steel-cut: whole groats cut into 2 to 4 pieces. Rolled: steamed and pressed thin, regular about 0.8 mm, quick about 0.4 mm, instant thinner still.

100. [The Grains, or Cereals] How important is rice in the world diet?

     It is the principal food of about half the world's population. In Bangladesh and Cambodia it supplies nearly three-quarters of daily energy.