FOOD

the material taken into the body in order to preserve life, and for _ the purpose of the growth and repair of the ti ues. It ought to contain proteins, carbohydrates (starch, sugar, and gum), fats, certain mineral salts, and water, and these substances are obtained from various sources. Meat has about 20 per cent. of protein, a varying percentage of fat, the greater part, usually over 70 per cent., being water. Grains, wheat, barley, etc., contain starch, and also a | small amount (7 to 11 per cent.) of protein, and when made into bread contain about 40 to 51 per cent. of carbohydrates, whole-meal bread sometimes containing a higher percentage of proteins than white bread. Oats, maize, and rye contain more fats than other grains, while rice has very little fats or protein. Beans, peas, and lentils have a large percentage of protein, and form a very nutritious food. Potatoes contain much starch, but very little proteins or fats, and should be combined with foods containing these substances. Vegetables and fruits are chiefly valuable for the salts and acids they contain. Milk is the most nutritious beverage, containing all the nece ary food substances, and infants obtain absolutely all the nutrition required from human milk, Tea, coffee, and cocoa are stimulants only, and have no nutritive value; while alcohol, especially in the form of beer and porter, is slightly nutritive as well as stimulating, but, in large quantities, has a depre ing and even dangerous action. Food Preservation has been practiced | by man in different forms since a primitive stage of civilization, drying and salting the flesh of animals, preserving fruit juices by fermenting them into wines, and drying and pre ing milk into cheese being well-known methods in very early times. Itis only within recent times, however, that the reasons for, and the principles of, food preservation have been really understood, for it is only since the middle of the 19th cent. that — it has been known that the decomposition of foodstuffs is not due to any property of the actual substances themselves, but to the action upon them of invading organisms. The modern methods are, therefore, directed towards preventing — the presence or destroying the life of — such organisms, a variety of different. systems being employed. The most general method is that — invented by Franco is Appert, which consists in packing the food to be pre- — served in cans, usually made of sheet — steel with a thin layer of tin upon it, — immersing them in a solution, and then © sterilizing them by exposure to steam at a: high temperature, the lid, and any hole © which has been made to allow of the ~ escape of the heated air, being closed — with solder. Meats of different kinds, © and fruits in syrup are preserved in this way. Fruit may also be preserved — by boiling in syrup and then drying (candied fruits), or by boiling with an equal weight of sugar until it breaks down slightly, both methods depending on the fact that sugar in solution has a bactericidal action; or the fruit may simply be heated in water of a sufficient temperature to effect sterilization in ve els which are then carefully closed so as to shut out air. Fruits—(e.g.) grapes, plums, apples—and also vegetables, are excellently preserved by drying. Salt is a fairly good preservative for meats, etc., but its taste is always very evident; while boracic acid, salicylic acid, and other chemical antiseptics are also becoming much used, but, while efficient preservatives, their effect on the consumer is injurious. The drying of meats is a method hardly practiced at all now, except a few instances abroad— (e.g.) biltong, a species of sun-dried meat in 8. Africa. Fish is dried, and sardines and other fish are preserved by packing them in oil; eggs, by submerging them in water-gla or lime water; and milk, either by heating to such a temperature as will kill any organisms it contains or by evaporating it down to a viscid consistency either with or without the addition of sugar, and packing in tins, or by drying to a powder. Refrigeration is a valuable method widely adopted today in preserving food, as organisms are unable to grow at a temperature below the freezing-point of water, and enormous quantities of meat—hbeef, mutton, etc.—fish, eggs, and fruit are imported frozen from Australia, New Zealand, the W. Indies, and other countries, and kept in this state till required. See ADULTERATION or Foon.