The chemistry of plant and animal life . s, for a few minutes, and for four hours, containspractically the same percentage amount of total the one case, however, the starch is in large masses,unruptured and unaltered, while in the other, the starchmasses have been ruptured, the particles are in a finerstate of division and are partially hydrated. Oatmealwhich has been cooked for only a few minutes does notreadily undergo digestion, but the four hours cookingproduces physical and intermediate chemical changesthat cause the starch toyield readily to the actionof the diastase
The chemistry of plant and animal life . s, for a few minutes, and for four hours, containspractically the same percentage amount of total the one case, however, the starch is in large masses,unruptured and unaltered, while in the other, the starchmasses have been ruptured, the particles are in a finerstate of division and are partially hydrated. Oatmealwhich has been cooked for only a few minutes does notreadily undergo digestion, but the four hours cookingproduces physical and intermediate chemical changesthat cause the starch toyield readily to the actionof the diastase the cooking ofmeats, the heat liquefiesa portion of the fat andoxidizes a portion of thatwhich is exposed to theair, while the proteidsundergo complex molec-ular changes. In thecooking and preparationof foods, it should be theobject to bring about physical rather than Fig. 102—composition of bread. chemical changes. Cooking influences the ease ratherthan the completeness of digestion. 509. Refuse and Waste Matters.—Nearly all foods. 388 AGRICULTURAL CHKMISTRY contain some refuse material which cannot be consumedas food. In average meat, as purchased in the market,from 7 to 56 per cent, is bone and trimmings. Roundsteak has least waste while shank has most. Tablesshowing the average amounts of refuse in meats are givenat the close of the chapter. The amount of refuse andwaste which a food contains is frequently large enoughto make the nutrients of the edible portion quite expen-sive even in apparently cheap foods. In vegetables, therefuse ranges from 15 to 50 per cent. About 15 percent, of the weight of potatoes is lost as parings ; of freshpeas, one-half of the weight is pods, and of squash, one-half the weight is rind and seeds. In calculating thenutrients of foods, the refuse and waste parts are to beconsidered, as there is nearly always a smaller percentageamount of nutrients in the food as purchased than in theedible portion. 510. Loss of Nutrients in the Preparation o
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