Proteid 4.1 Calories. Carbohydrates 4.1 „ Fat 9.3 „
The method of applying this standard to a food is as follows: the percentage of proteid or carbohydrate given in the following table is multiplied by 4.1, and the percentage of fat by 9.3:—
┌────────────────────────────┬──────────────────────────────────────────┐ │ │ IN 100 PARTS. │ │ ├──────┬────────────┬─────┬────────┬───────┤ │ │WATER.│ALBUMINATES │FATS.│ CARBO─ │ SALTS.│ │ │ │OR PROTEIDS.│ │HYDRATES│ │ ├────────────────────────────┼──────┼────────────┼─────┼────────┼───────┤ │_Uncooked meat with little │ │ │ │ │ │ │ fat_ │ 74.4 │ 20.5 │ 3.5 │ ─ │ 1.6 │ │_Cooked meat─without loss_ │ 54 │ 27.6 │15.45│ ─ │ 2.95 │ │_Salt beef_ │ 49.1 │ 29.6 │ 0.2 │ ─ │ 21.0 │ │_White fish_ │ 78.0 │ 18.1 │ 2.9 │ ─ │ 1.0 │ │_Bread, white wheaten_ │ 40. │ 8. │ 1.5 │ 49.2 │ 1.3 │ │_Wheat flour_ │ 15. │ 11. │ 2. │ 70.3 │ 1.7 │ │_Rice_ │ 10 │ 5 │ .8 │ 83.2 │ 0.5 │ │_Oatmeal_ │ 15 │ 12.6 │ 5.6 │ 63.0 │ 3. │ │_Peas (dry)_ │ 15 │ 22 │ 2. │ 53. │ 2.4 │ │_Potatoes_ │ 74 │ 1.5 │ .1 │ 23.4 │ 1. │ │_Butter_ │ 8 │ 2. │88 │ ─ │variable│ │_Eggs (including shell, for │ │ │ │ │ │ │ which deduct 10 per cent.)_│ 73.5 │ 13.5 │11.6 │ │ 1 │ │_Cheese_ │ 36.8 │ 33.5 │24.3 │ ─ │ 5.4 │ │_Milk_ │ 87.0 │ 4. │ 3.5 │ 4.8 │ .7 │ └────────────────────────────┴──────┴────────────┴─────┴───────┴────────┘
Proteid 8 × 4.1 = 32.8 Fat 1.5 × 9.3 = 13.95 Carbohydrate 49.2 × 4.1 = 201.72 —————— Total Caloric value of 100 grammes of bread = 248.47
The total fuel value in Calories of one pound of certain typical foods is given by Hutchison as follows:—Butter 3,577, peas 1,473, cheese 1,303, bread 1,128, eggs 739, beef 623, potatoes 369, milk 322, fish (cod) 315, apples 238.
2. =The Physiological Test.=—Not only is a proper proportion of proteid, fat, and carbohydrates required, but these must be capable of digestion and absorption and of oxidation in the body. Cheese is a highly concentrated food, but its value is less than its percentage composition would indicate, because of the difficulty of digesting considerable quantities of it. Green vegetables consist largely of cellulose, which is only imperfectly capable of absorption into the blood, although it can experimentally be oxidised by combustion. The proportion between absorbed food and food rejected in the fæces can be ascertained by analysis. Many experiments made on these lines show that on a purely animal diet (meat, eggs, milk) but little nitrogen is lost, while with vegetable foods (carrots, potatoes, peas, etc.) the waste of nitrogen is considerable. Fats are very completely absorbed from the alimentary canal. The amount remaining unabsorbed is greatest with mutton fat (10 per cent.), least with butter (2½ per cent.). Experimentally it has been found that an amount up to 150 grammes (about 5½ oz.) of fat can be absorbed without appreciable loss. Carbohydrates are very completely absorbed, even starchy foods rarely escaping digestion. Completeness of absorption from the alimentary canal is not desirable for all foods; a certain amount of unabsorbed residue is required to stimulate peristalsis. With a purely vegetable diet this amount is excessive, and there is physiological waste of effort.