GLUTEN is one of the most important constituents of the varieties of corn used as food. It is obtained by Mixing flour with water, and thus forming a paste or dough.
This paste is placed in a bag of fine linen, and kneaded in water, which must be repeat edly changed, till it ceases to assume a milky appearance. A gray, tenacious, viscous, tasteless substance, having the appearance of bird-lime, is left in the bag. This sub stance consists mainly of gluten, mixed with traces of bran starch and of oily matter. The gluten thus obtained from wheat and from rye is far more tenacious than that which is obtained from the other cereals, and it is the great tenacity of this constituent that especially fits these flours for conversion into bread. It is found, by analysis, that the proportion of gluten contained in wheat grown in Algeria and other hot countries is considerably higher than in wheat grown in England or still colder countries; and the hard, thin-skinned wheats contain more of this ingredient than the softer varieties of the grain. It forms about 16 per cent of Algerian wheat; about 15 per cent Of wheat from the Black sea; and nearly 14 per cent of South Carolina wheat; about 10.7 per cent of English Wheat; 9.8 per cent of Canadian wheat; and less than 9 per cent of Dantzig wheat.
Gluten in a moist state rapidly putrefies, the mass acquiring the smell of decaying cheese; but when dry, it forms a hard, brownish, horny-looking mass, that does not very readily decompose. On treating gluten with hot alcohol, we find that, it resolves itself into at least two distinct substances, one of which is soluble, and the other insoluble in that fluid.
The insoluble portion is regarded by Liebig as vegetable fibrine. It is a gray, `tough, elastic substance, insoluble in water or in ether, but readily soltIble in dilute alkalies, from which it is precipitated by neutralization with acetic acid. It is also soluble in very dilute hydrochloric acid, from which it is thrown down by salts. ' The soluble portion is in part precipitated from the alcohol on cooling, in the form of flakes, which have the composition and properties of caseine; while a third substance remains in solution, giving to the alcohol a sirupy consistence. It separates, on the addition of water, as a white substance resembling albumen. It is usually known as gliadia, but sonic chemists—Dumas and Cahours, and others, have termed it gtutine, a name which is ebjectionable on the ground that it is already engaged for the chief form of gelatine. All these constituents of gluten contain carbon, hydrogen, nitrogen, oxy gen, and sulphur, in much the same proportion as the anima] albuminates or protein° bodies, and they all doubtless belong to the flesh-forming group of foods.
• The action of gluten in the manufacture of bread is probably a double one; it induces, by constant action, an alteration of the starch, and subsequent fermentation, while by its tenacity it prevents the escape of carbonic acid gas.