The purposes of cooking are threefold— (1) to assist digestion by preparing the food for the action of the digestive juices ; (2) to quicken the flow of the saliva and digestive juices by making food pleasing to the palate and other senses, and (3) to destroy by heat any disease germs or parasites that it may contain.
In order to avoid incorrect deductions from a study of the tables given, we may add that, though the chief purposes of food are to build the body and supply it with the necessary warmth and energy, and that therefore the principal foods may be judged by their percentage of protein, fat and carbohydrates, etc., the limitations of the human digestive organs must always be borne in mind. Cheese, for example, is rich in both protein and fat, and the peanut in protein, fats and carbohydrates— either should apparently be most valuable as a leading article of diet, but the average digestion will accept and assimilate them only in small quantities.
On the other hand, many vegetables which show but very small percentages of food value are of vital importance because of the salts they contain and because their special composition assists in the digestion of the main foods. Many fruits have this useful quality in addition to high food value.
The average American diet is not so far from being correct as many critics declare and it could be made an excellent standard by decreasing the amount of meat generally consumed and increasing the proportion of green vegetables and fruits. Au excessive consumption of meat means an over-supply of protein which doubles the work—and therefore the risks—of nature to dispose of it or to convert it into carbo hydrates, in the latter case endangering the balance of health by giving the system too great a supply of fuel—for, as already noted, there is an ample supply of carbohydrates in all popular diets, the only lack in other than American being in the supply of diminutive size.
In fresh meats, they are due to the extractives which in varying proportions form part of the protein. Some "game" birds are especially rich in that respect—hence the high „esteem in which they are held by epicures. The flavors of fruits and vegetables
are usually attributable to similar components. The extractives are generally enhanced by the process of cooking—and in meats, birds, etc., are also developed by "aging in a greater or less degree.
In. many other foods, the distinctive flavor, instead of being an essential part of their natural development, hinges on the special methods of their commercial prepara tion. In hams and other smoked meats, it is largely due to the acid in the wood smoke in which they are suspended. In black tea, cheese, butter and many other exampleS, it is the result of chemical changes brought about by the growth and respi ration of microscopic plants during manufacture—for all plants, whether microscopic or visible, breathe as do human beings, producing the same chemical change of the oxygen of the air into carbon-dioxide.
The difference between green and black tea is attributable chiefly to the fact that for the latter the tea leaves are allowed to ferment before they are "fired" or roasted. This, translated in the light of modern botanical knowledge, means that the micro scopic plants in the moist leaves are permitted to respire for a time before they are killed by the heat applied in the firing machines.
The difference between Camembert and Swiss cheese—or any other varieties—is similarly the difference in the microscopic plants which respired within them during the process of ripening—plants furthermore that can be transplanted in spite of their protein.
See articles on BACTERIA, Mom) and YEAST.