Caloric Value of Food

the energy accumulated in food substances (proteins, fat, and carbohydrates); the energy value of foodstuffs, expressed in calories (cal) or kilocalories (kcal). The concept is used, for example, in the comparative evaluation of food products and in planning diets.

The caloric value is determined by the presence of unoxidized atoms of carbon and hydrogen. A molecule of fat contains more unoxidized atoms of carbon and hydrogen than a carbohydrate molecule or a molecule of protein. One g of fat yields 9.3 kcal (1 kcal = 4.1868 × 10³ joules); 1 g of carbohydrate, 4.1 kcal; and 1 g of protein, 4.1 kcal. The following gives the caloric value (in kcal) of some products (per 100 g): milk (kefir, sour milk), 62; butter, 734; first-grade beef, 154; first-grade mutton, 206; ham, 365; choice sausage, 290; eggs, 150; scallions, 21; fresh cucumbers, 15; potatoes 89; cabbage, 27; carrots, 36; apples, 48; lemons, 41; cepes, 32; walnuts, 612; rye bread, 204; and sugar, 390. The caloric value of foodstuffs must be known in order to work out rations, which are determined by the energy expenditures of persons of different occupations, sexes, and ages.

In animal husbandry, the caloric value is used in the compara-tive evaluation of the nutritional value of feeds, for establishingnorms of feeding livestock, and for planning feed requirements.The caloric value of dry matter in most feeds is 4.0-4.5 Meal per1 kg. The useful caloric value of a feed for the animal dependson the digestibility of the feed and the absorbability of the digest-ible substances.