Foods : nutritive value and cost / by W.O Atwater.

  • Wilbur Olin Atwater
Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: Foods : nutritive value and cost / by W.O Atwater. Source: Wellcome Collection.

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    Along with the muscle the meat contains tendon and cartilage, which are familiarly called gristle. These materials and the ossein, or uani¬ mal matter” of bone, are very similar to gelatin (glue), and are changed to gelatin on heating with water. They are hence termed gelatinoids. The gelatinoids are the principal ingredients of tendon and similar tissues, while the albuminoids are the chief ingredients of muscle. There is still another class of nitrogenous substances in meat, which, though small in quantity, are very interesting. They are known in the chemical laboratory as creatin, creatinin, carnin, etc., and are grouj>ed together as u extractives,” because they are extracted from flesh by water. They are the chief constituents of beef tea and most meat extracts. The albuminoids and gelatinoids may be properly grouped together as proteids. It is customary to use the term protein to include albuminoids, gelatinoids, and extractives. Fat.—Fat is familiar to us in meat, from which we get it in the form of tallow and lard; in milk, from which it is obtained as butter; and in the various vegetable oils, such as olive oil, cotton-seed oil, and the oils of wheat and corn. Larger or smaller proportions of fat are found in most food materials. Carbohydrates.—Potatoes, wheat, and corn contain large proportions of starch. Sugar cane and sorghum are rich in sugar. Starch and sugar are very similar in chemical coinpositio n and are called carbo¬ hydrates. Other carbohydrates are found in animals and plants, such as glycogen or uanimal starch,” which is found in the liver, and cellu¬ lose, which occurs in plants. Ash.—The mineral matter, or ash, which is left behind when animal or vegetable matter is burned, consists of a variety of chemical com¬ pounds commonly called salts, # and includes phosphates, sulphates, and chlorides of the metals, calcium, magnesium, potassium, and sodium. Calcium phosphate, or phosphate of lime, is the chief mineral constit¬ uent of bone. Common salt is chloride of sodium. These substances are separated from each other in the laboratory by various methods of analysis. The everyday handling of food materials also involves crude processes of analysis. We let milk stand; the globules of fat rise iu cream, still mingled, however, with water, protein, carbohydrates, and mineral salts. To separate the other ingredients from the fat, the cream is churned. The more perfect this separation—i. e., the more accurate the analysis—the better will be the butter. Put a little rennet into the skimmed milk and the casein, called in chemical language an albuminoid or protein compound, will be curdled and may be freed from the bulk of the water, sugar, and other ingredients by the cheese press. To separate milk sugar, a carbohydrate, from the whey is a simple matter. One may see it done by Swiss shepherds in their Alpine huts. But farmers find it more profitable to put it in the pigpen, the occupants of which
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