the needs of moderate persons for a beverage at luncheon and dinner, the only two meals at which alcohol should, as a rule, be taken." CIDER. Cider is a beverage prepared from the fermented juice of ripe apples. The amount of alcohol contained in this beverage varies between 3 and 8 per cent. by volume. It also contains malic acid, salts, sugar, albuminoids, and extractives. Cider is a diuretic drink and acts as a laxative. On exposure it undergoes an acetic acid fermentation, whereby it is rendered unfit for drinking purposes. The table on p. 1691 gives analyses of American ciders. 1 Crampton, Foods and Food Adulterants, U. S. Department of Agriculture, Bulletin No. 13, 1877. VARIOUS FACTORS IN THEIR BEARING CONCENTRATION OF FOOD. CONCENTRATED foods are those from which the larger portion of the water present has been abstracted, and thus the weight and the bulk of the food diminished. There are many patented concentrated foods on the market. They find their chief use in the treatment of patients who take too little of the usual forms of food to maintain strength, and, second, in cases where it is important that a large quantity of nourishment be taken. Food can be concentrated to various degrees. Desiccated meat is the most concentrated form of protein; sugar, the most concentrated form of carbohydrate; and olive oil, the most concentrated form of fat. 1. Concentrated Proteins.-These foods are prepared from milk, meat, eggs, and vegetables. Meat is concentrated by drying, and in this form it is generally indigestible; which can, however, be overcome by predigestion or powdering; in this class of foods are included somatose, pemmican, and Mosquera's "Beef Meal" (see p. 175). Among the concentrated foods derived from the casein of milk are nutrose, eucasein, etc. (see p. 174). Eggs are dried in vacuo; sugar is usually added, and the eggs are then pulverized. vegetable proteins utilized in concentrated form are aleuronat and legumin. Of the 2. Concentrated Carbohydrates.-Sugar is the most important of the concentrated carbohydrates. In this form, however, it is apt to disagree and cause fermentation. To this class of concentrated carbohydrates belong, the malt extracts. 3. Concentrated Vegetables.-Many vegetables, such as potatoes, carrots, cabbage, and the like, are concentrated by drying. They are utilized only in those instances in which it is impossible to secure fresh vegetables. Bread is frequently dried and eaten in the form of "hardtack," when it is impossible, as during voyages, to obtain fresh bread. PRESERVATION OF FOOD. By preservation of food is meant the process by which the food is so changed that it can be kept for a longer or shorter period of time without undergoing putrefaction. The process of fermentation is induced by micro-organisms present in the atmosphere coming into contact with the food and contaminating it. Since putrefactive germs require a certain amount of moisture and heat for their growth, such foods as contain little water and that are not kept too warm are not so likely to undergo decomposition; on the other hand, foods containing much water undergo fermentation very rapidly. To prevent this process four methods of preservation are, according to Yeo,' available: 1. Drying. 2. Exclusion of the air. 3. Exposure to cold. 4. Treatment with antiseptic chemic agents. 1. Drying. By this process a large proportion of the water is abstracted. Pemmican is a form of meat preserved by this method (see p. 174). Vegetables, such as carrots, peas, potatoes, etc., are also preserved by drying. Milk, in the form of nutrose, eggs, as egg powder, and fruits are often preserved in this manner. 2. Exclusion of Air.-Air may be prevented from coming into contact with food in a number of ways: by immersing the food in oil or fat; by heating the food, so as to evaporate the external layers; by coating with some impermeable substance, as oil, salt, sawdust, varnish, or paraffin. Fish are frequently preserved by immersion in oil or by smoking. Ham and bacon are preserved by smoking, by which process the outer surface becomes coagulated and impermeable. Eggs are preserved by covering the fresh eggs with some impermeable substance, such as oil, fat, beeswax, or sawdust. In order properly to preserve food by exclusion of air it is highly important that the food be perfectly fresh, and that any air that may be present be expelled. In canning, the food to be preserved is heated in tin cans until steamed, when, all the air having been expelled, the can is soldered and rendered air-tight. Various methods have been resorted to to obviate the necessity of cooking in preserving food. McCall advises the partial exclusion of air and the disinfection of what remains with sodium sulphite. A method of replacing the air by nitrogen and sulphurous acid has also been recommended. 1 Food in Health and Disease, p. 176. 3. Exposure to Cold.-Food can be preserved indefinitely by ice. Meat and fish, which are often preserved by this means, should be cooked at once after thawing. Frozen meat loses about 10 per cent. more of its nutritive value in cooking than fresh meat. Frequently food is not kept directly on ice, but in refrigerating chambers; it can thus be shipped many thousands of miles on land or water without showing the slightest tendency to decomposition. The use of cold storage for indefinite periods of time is to be condemned, and storage warehouses should be compelled to brand all stored food as such, as well as with the date of entrance. 4. Treatment with Antiseptic Chemic Agents.Under ordinary circumstances the only chemic agents allowable in preserving food are salt, sugar, vinegar, and wood smoke. 1. Salting. The salting of food is a method that has been practised for many centuries. In this way meat and fish are easily preserved. The pale color of the meat produced by salting is overcome by adding a little saltpeter in addition to common salt. By salting, considerable proteins are extracted from the meat-according to Liebig, one-third of the nutritive value of the meat is lost in this way. After the salting has been accomplished it is often followed by smoking. 2. Sugar in strong solution acts as an antiseptic, and fruits are thus often preserved in concentrated syrups. 3. Vinegar acts as an antiseptic in preserving cucumbers, pickles, oysters, etc. 4. Other Antiseptics for Preserving Foods.—Among these substances are sulphur vapor; weak carbolic acid; strong acetic acid; injections of alum and aluminium chlorid into the blood-vessels; boric acid; borax; salicylic acid; formaldehyd. Chittenden and Gies have studied the effect of borax and of boric acid on the general nutrition. They conclude that, taken in small doses for a long time, borax does not alter metabolism or disturb nutrition. In larger doses borax retards protein and fat assimilation. In very large doses it causes nausea, vomiting, and diarrhea. (See Food Adulteration, p. 204.) Wiley has made an extended study of food preservatives, and concludes that boric acid and borax used even in small quantities over long periods of time disturb appetite, digestion and the general health. The fact that certain individuals may take small amounts of certain food preservatives for long periods of time without injury is no argument in favor of their use, as 1 Amer. Jour. Physiol., 1898, No. 1. 1United States Department of Agriculture, Bulletin 84. Part I. |