grain

grain,

in agriculture, term referring to the caryopsis, or dry fruit, of a cereal grass. The term is also applied to the seedlike fruits of buckwheat and of certain other plants and is used collectively for any plant that bears such fruits. The food content of the seeds (as they are commonly called) is mostly carbohydrate, but some protein, oil, and vitamins are also present. Grain, whole or ground into meal or flour, is the principal food of man and of domestic animals. The seeds of most grains grow in concentrated clusters that are gathered efficiently by modern mechanical harvesting machines (see combine). Grain is easy to handle and, because of its low water content, can be stockpiled and stored for long periods, unlike other starch foods (e.g., the potato). Grains, both living and stored, are attacked by a variety of insect pests (e.g., the corn borer, locust, and grasshopper) and by smuts, rusts, blights, rots, and other diseases of plants. The principal grain crops, in order of total world output, are wheat, rice, Indian corn (or maize), oats, barley, and rye; together, these grains occupy about half of all the land under crops. All the staple grains were domesticated in the Neolithic period, or New Stone Age, and their cultivation was a powerful factor in drawing men into settled communities. Many religious beliefs and rites have been associated with grains; the cereals derive their name from Ceres, the Roman goddess of grain. Grain has been an article of commerce in nearly all civilizations.

Bibliography

See N. L. Kent, Technology of Cereals (1983); Y. Pomerantz, Modern Cereal Science and Technology (1987).

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grain,

in weights and measures: see English units of measurement.

Grain

The pattern of fibers found on the cut surface of wood.

Grain

 

an obsolete unit of weight used in Russian pharmaceutical practice before the introduction of metric units of measure; one grain equaled 62.2 mg. In the British system the grain—commercial, apothecaries’ and troy (used in weighing precious metals)—is equal to 64.8 mg.

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Grain

 

(1) The fruit of cereal grasses and the seed of legumes.

(2) The product of grain production. Grain is one of the principal human food products, a raw material for the flour, groats, beer, starch, alcohol, and mixed feed industries, and a concentrated feed for farm animals. The products of grain processing are used in the baking, macaroni, and confectionery industries. Grain is the most important part of the state food reserves and an export.

The grain of cereal grasses is a dry, monospermous fruit (caryopsis) that is glabrous in wheat, rye, corn, and the naked forms of barley and oats and tunicate (covered with flowering husks) in oats, barley, rice, and millet. The heaviest part of the grain is the endosperm, from which the most valuable part of flour is obtained during milling. Most of the cells of the grain are filled with starch and protein. The outermost layer of the endosperm—the aleurone layer—is rich in proteins and fat. The layer next to the aleurone contains the most protein. During graded milling the aleurone layer is separated from the grain and discarded, because the human organism does not digest it well. Depending on the dimensions, shape, and location of the starch grains and on the properties and distribution of proteins, the grain may be vitreous, semivitreous, or mealy.

In the lower part of the grain is the seed, the embryo of the future plant. It contains a great deal of protein, fat, sugars, vitamins, and enzymes. During graded milling the seed is removed because it is difficult to crush and because the fat contained in it turns rancid easily and ruins the flour during storage. The exterior of the grain is covered with the fruit and seed shells, which are generally discarded during graded milling. In wheat grain, the weight ratio of the endosperm (in percentages) is 81.1–84.2, of the aleurone layer, 6.8–8.6, of the seed, 1.4–3.2, and of the shells, 3.1–5.6. In oats, the endosperm is 51–61 percent of the total weight of the grain, the aleurone layer, 4–6 percent, the seed, 3–4 percent, the shells, 2–4 percent, and the flowering husks, 20–40 percent.

The mature grain of legumes has no endosperm. It is covered with a seed membrane (skin), under which lies the seed, which consists of meaty cotyledons and the embryonic stock, root, and plumule. In the most common legumes, the shell is 6.4–11 percent of the total weight of the grain, the cotyledons, 87.2–92.5 percent, and the root, stock, and plumule, 1.1–2.5 percent. (See Table 1 for the average chemical composition of grains, given a moisture level of 14 percent.)

Table 1. Chemical composition of grains (in percent)
Crops	Proteins	Fats	Corbohydrates, excluding cellulose	Cellulose	Ash
Wheat
soft	120	1 7	687	20	1 6
durum	138	1 8	666	2.1	1.7
Rye	11.0	1 7	69.6	1.9	1.8
Barley	10.5	2.1	66.4	4.5	2.5
Oats	10.1	5.2	58.9	9.9	2.0
Corn	100	46	67.9	2.2	1.3
Buckwheat	11.3	2.7	58.3	11.3	2.4
Rice	6.6	1.9	62.3	10.2	5.1
Peas	23 4	2 4	53.1	4.7	2.4
Beans	232	2 1	53.8	3.6	3.3
Soybeans	34.0	18.4	24.6	4.5	4.5

The basic component of grain carbohydrates is starch, whose hydrolysis is very important in the preparation of dough. Cellulose and hemicellulose are part of the composition of the cell walls. Maltose, glucose, and fructose are among the sugars found in grains. The proteins in cereal grass grains are primarily prolamins and glutelins. The principal proteins in wheat are gliadin and glutenin, which form gluten, whose quantity and quality determine the elasticity of the dough and the porosity and volume of the bread. The gluten in rye (which is separated out under special conditions) and of barley (which is not contained in all grades of grain) does not have the valuable physical properties of wheat gluten. The proteins in legumes consist primarily of globulins and a small number of albumins. They are richer than the proteins of the cereal grasses. In most grains, the largest quantity of fats (primarily unsaturated fatty acids) is contained in the seed, but in peanuts and soybeans the fats are concentrated in the cotyledons. Grain ash contains phosphorus, potassium, magnesium, calcium, silicon, and other elements (in the form of oxides).

Enzymes are concentrated primarily in the embryo. The most important of them are α-amylase, β-amylase, orglucosidase (maltase), β-fructofuranosidase (invertase), lipase, protease, and catalase. Grain contains numerous vitamins, which are concentrated in the seed and the peripheral layers. Among them are thiamine (B₁), riboflavin (B₂), pyridoxine (B₆), nicotinamide (PP), ascorbic acid (C), and, in germinated grain only, pantothenic acid and the pigment carotene, the source of retinol (vitamin A).

The quality of grain is evaluated on the basis of its freshness, color, odor, taste, acidity, weediness, moisture, character (weight of 1 liter), weight of 1,000 grains, and the cleanliness of the grain stores, which should be free of pests and diseases. In production evaluation (flour milling and baking), vitreousness, ash content, and protein content are often determined. Experimental bread is baked from flour and evaluated (volume of bread produced per 100 g flour and stability of the shape of bread). In the USSR the quality of grain is evaluated according to state standards, and standardized conditions have been established for processing grain. The quality of export grain is graded according to technical specifications.

REFERENCES

Kretovich, V. L. Biokhimiia Zerna i Khleba. Moscow, 1958.
Koz’mina, N. P.Zerno i produkty ego pererabotki. Moscow, 1961.
Kazakov, E. D.Zernovedenie s osnovamirastenievodstva. Moscow, 1965.
Spravochnik po kachestvu zerna i produktov ego pererabotki. [Compiled by V. T. Tevosian, B. M. Mashkov, and F. I. Biriukov.] Moscow, 1965.
Koz’mina, N. P. Zerno. Moscow, 1969.

E. D. KAZAKOV

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Grain

 

a pattern on leather. In manufacturing leather, irregularities remain on the surface of the corium after the removal of the epidermis (which extends somewhat into the corium). These irregularities, together with pores, form the grain. The skin of each species of animal has its characteristic grain, making it possible to distinguish leathers. An artificial grain can be given by embossing a pattern on the leather.

What does it mean when you dream about grain?

Grain represents an opulent harvest and is often symbolic of a good life.

grain

[grān]

(botany)

A rounded, granular prominence on the back of a sepal.

cereal drupelet

(geology)

The particles or discrete crystals that make up a sediment or rock.

(graphic arts)

A small particle of metallic silver remaining in a photographic emulsion after developing and fixing; these grains together form the dark areas of a photographic image.

(hydrology)

The particles which make up settled snow, firn, and glacier ice.

(materials)

The appearance and texture of wood due to the arrangement of constituent fibers.

The woodlike appearance or texture of a rock, metal, or other material.

The direction in which most fibers lie in a sample of paper, which corresponds with the way the paper was made on the manufacturing machine.

(mechanics)

A unit of mass in the United States and United Kingdom, common to the avoirdupois, apothecaries', and troy systems, equal to 1/7000 of a pound, or to 6.479891 × 10^-5 kilogram. Abbreviated gr.

(ordnance)

A single piece of solid propellant, regardless of size or shape, used in a gun or rocket; a rocket grain is often very large and shaped to fit its requirements.

(textiles)

The direction in a piece of fabric which is parallel with the selvage.

grain

1. The direction, arrangement, or appearance of the fibers in wood, or the strata in stone, slate, etc.

2. The easiest cleavage direction in a stone.

3. Any small, hard particle, as of sand.

4. A unit of weight measure in the English system of units; 7,000 grains equals 1 lb; used as a measure of the weight of moisture in air.

grain

As it pertains to photography, a small particle of metallic silver remaining in a photographic emulsion after development and fixing. In the agglomerate, these grains form the dark area of a photographic image.

grain

1. the small hard seedlike fruit of a grass, esp a cereal plant

2. a mass of such fruits, esp when gathered for food

3. the plants, collectively, from which such fruits are harvested

4. 

a. the granular texture of a rock, mineral, etc.

b. the appearance of a rock, mineral, etc., determined by the size and arrangement of its constituents

5. the smallest unit of weight in the avoirdupois, Troy, and apothecaries' systems, based on the average weight of a grain of wheat: in the avoirdupois system it equals 1/7000 of a pound, and in the Troy and apothecaries' systems it equals 1/5760 of a pound. 1 grain is equal to 0.0648 gram

6. a metric unit of weight used for pearls or diamonds, equal to 50 milligrams or one quarter of a carat

7. the threads or direction of threads in a woven fabric

8. Photog any of a large number of particles in a photographic emulsion, the size of which limit the extent to which an image can be enlarged without serious loss of definition

9. Chem any of a large number of small crystals forming a polycrystalline solid, each having a regular array of atoms that differs in orientation from that of the surrounding crystallites

GRAIN

(1)

A pictorial query language.

["Pictorial Information Systems", S.K. Chang et al eds, Springer 1980].

grain

(2)

granularity

grain

One element. A tiny part of a larger system. See granularity.