Imágenes de páginas



1. STRUCTURE AND COMPOSITION. 436. Relationships. — Barley (Hordeum sativum Jensen) belongs to the same tribe as wheat and rye, and differs from both in that the spikelets are one-flowered, and in having more than one spikelet at the joint of each rachis.

437. The Plant. Aside from the spike, the barley plant has much the same appearance and habit of growth as wheat. Usually the culms are not so tall, and are perhaps more variable on account of environment. Wisconsin Station found with several varieties during five years an average of one pound of straw for each pound of grain, there being considerably less straw than is usually obtained with wheat or oats. In a comparative trial the proportion of top to root in weight of dry matter was 3.3 to one in barley and 2.2 to one in oats. The indication is that it is more shallow rooted than wheat, maize or oats. Although the roots grow rapidly, they are comparatively feeble and short lived.

438. The Inflorescence.—The spikelets are one-flowered, sessile, thus forming a spike. The outer glumes are almost awishaped, three-eighths inch long with flexible beard one-half to three-fourths inch long. Flowering glume, which with palea is adherent to fruit, is prolonged into a stiff beard six to eight inches long with strongly barbed edges, making barley a disagreeable crop to handle, although the objection to the beards

1 Wis. Rpt. 1903, p. 268. 2 Wis. Rpt. 1892, p. 119.

huu, sometimes the huske 9000/10000

has been considerably lessened by the introduction of the selfbinding harvester, and in the Western States by the header and combined harvester and thresher. As there are three spikelets at each joint of the rachis, each joint bears six outer glumes. There are three stamens and a double feathery stigma similar to wheat. In the six-rowed type there are three spikelets at each joint of the rachis, and these joints are close together, thus forming a square, rather compact spike, which may be four or six-rowed, depending upon whether or not the side rows overlap.

439. The Grain.—The barley kernel, like the oat kernel, remains enclosed, except in hull-less varieties, in the flowering glume and palea, from which it is with some difficulty removed. These parts are called the hull, sometimes the husk. In this book the caryopsis of the barley will be called the kernel, and the kernel plus the hull will be called the grain. (388) Although the grain of barley is quite Selected grains of barley, natural size different in appearance from

(After Hicks and Dabney.) a grain of wheat, when the hull is removed the resemblance is quite close, having like wheat a deep furrow on the side opposite the embryo. It is somewhat broader, with sides more rounded and upper end more pointed.

Barley grains are a little wider than thick, varying from onefifth to one-tenth of an inch in width, one-seventh to one-twelfth of an inch in thickness, and from one-fourth to one-half of an inch in length. The word barleycorn is sometimes used as a measure of length, meaning one-third inch. The weight of 100 grains varies from 2.5 to five grams, the average being about 3.5 grams, or about 1,300 grains to the pound. In the sixrowed barley the lateral grains are slightly smaller than the central ones. Two-rowed varieties have plumper and longer

[ocr errors]

grains than six-rowed varieties. Grains coming from the Rocky Mountain and Pacific Coast States are likewise longer and plumper than those from the North Central and North Atlantic States.

440. The Hull.—The hull or husk of barley may constitute less than ten per cent or as much as twenty-five per cent of the grain. The average is probably about fifteen per cent, or half that of the oat grain. Grains of the six-rowed barley have thicker hulls than the two-rowed barley. The hull of barley is of value in the process of malting by protecting the embryo during germination and subsequently acting as a filter when the malt is extracted. The rudiment of the second flower is attached at the base of the flowering glume and lies almost concealed in the furrow next the palea. This feathery appendage about half the length of the grain is said to be a ready channel for the conveying of moisture to the kernel.

441. The Character of the Endosperm.—The endosperm varies in texture (not structure) and color from mealy white to glassy or vitreous. (238) The character of the endosperm varies with (1) the variety, the two-rowed being more mealy than the six-rowed; with (2) the maturation, fully but not overripe grains being the most mealy; and with (3) the climate, a moist and insular climate being most conducive to complete maturation. (74) As in wheat and maize, a glassy or translucent endosperm is accompanied by high percentage of protein and a corresponding decrease of starch. The character of the endosperm may be determined by cutting the grain across with a sharp instrument. In an average of thirty-six samples of American barley, Wahl and Henius report sixteen per cent of the grains mealy; fifty-two per cent half glassy, and thirty-two per cent glassy. The character of the endosperm may also be determined by placing the grains of barley by suitable contrivance between the observer and a strong light, when the number of opaque, partly opaque and translucent grains may be determined.

442. The Embryo.—The embryo is very similar to that of wheat. On account of the plumule becoming twisted upon germination it is known as the acrospire. For good malt the acrospire should be three-fourths the length of the grain, and the radicle or root should be twice that length.

443. Composition.—Barley grain is more carbonaceous than either wheat or oats. The grain has more crude fiber on account of its hull; otherwise its proximate composition is very similar to wheat. An analysis of hulled barley is almost identical with that of wheat. Barley differs principally from maize in having a less per cent of fat and higher per cent of crude fiber. Oats contain about three times as much crude fiber as barley; yet the hull of barley is so tough that it is essential to grind it before feeding it to domestic animals, while this is not necessary with oats.

Barley also has less fat and more starch, the starch taking the place of the extra crude fiber in the oats. Barley straw is similar to wheat straw, and barley hay has more protein and less crude fiber than timothy hay. No summary of comparative analyses of American grown two-rowed and six-rowed varieties has been reported. Wahl has reported a two-rowed variety (Chevalier) grown in Montana containing 9.23 per cent of protein and a six-rowed variety grown in Minnesota with 15.16 per cent protein.

444. Weight per Bushel.—The legal weight per bushel in Canada and most of the States is forty-eight pounds. A variation from forty-five to fifty pounds is to be found in other States. Variations in weight of measured bushel from forty-two to sixty-eight pounds have been recorded. Variations between forty-five to fifty-five pounds are not uncommon. Hull-less barley usually weighs about sixty pounds to the bushel. The weight per bushel depends much upon the thoroughness with which the beards are removed. In order to accomplish the thorough removal of beards, the grain is sometimes put through the threshing machine a second time. At elevators where much barley is shipped special machinery is used for thoroughly scouring and cleaning it.

1 R. Wahl: High or low albumen content in barley malt?

High weight per bushel has been shown to be associated with high weight per grain and consequently, other things equal, greater yield. Other things equal, high weight per bushel indicates low percentage of protein and high percentage of kernel to grain; because (1) starch has a higher specific gravity than protein, and (2) kernel has a higher specific gravity than hull.

445. Qualities for Malting.—The ability to germinate completely, quickly and uniformly are essential qualifications for malting. Uniform ripeness, uniform size and purity of variety aid uniformity of germination. The two-rowed and six-rowed varieties must not be mixed, since the plump grains of the former take longer to germinate than the thinner grains although thicker hulls of the latter. Barley should be free from impurities, should not have broken grains or be threshed too short.

“A good brewing barley should have a thin, clean, wrinkled husk, closely adhering to a plump, well fed kernel, which, when broken, appears white and sweet, • with a germ full and of a pale yellow colour. The specific gravity being between 1.280 and 1.333, and weighing from 53 to 58 pounds 1 per bushel." 2

The European maltsters almost universally prefer a mealy endosperm rather than a glassy one. The higher percentage of protein decreases the percentage of starch and this lowers the percentage of malt extract. In addition to this, the higher percentage of protein causes a larger percentage of protein in the beer. Some of the protein compounds are insoluble at high and low temperatures but are soluble at ordinary temperatures. When beer is placed upon ice these protein

• Imperial bushel, 2,218.2 cu. in.; United States Standard (Winchester) bushel 2,150.42 cu. in.

7 Quoted in Can. Expt. Farms Rpt. 1895, p. 231.

« AnteriorContinuar »