The Chemistry of Food and Nutrition | Page 3

Soluble dry matter 0.97 3.38 1.43 7.66 per cent. Ash 0.16 0.40 0.28 1.26 " " Alkalinity as K_{2}O 0.02 0.082 0.084 0.21 " "
The loss on soaking in cold water, unless the water is preserved, is seen to be considerable. The split lentils, having had the protecting skin removed, lose most. In every case the ash contained a good deal of phosphate and lime. Potatoes are rich in important potash salts; by boiling a large quantity is lost, by steaming less and by baking in the skins, scarcely any. The flavour is also much better after baking.
The usual addition of common salt (sodium-chloride) to boiled potatoes is no proper substitute for the loss of their natural saline constituents. Natural and properly cooked foods are so rich in sodium chloride and other salts that the addition of common salt is unnecessary. An excess of the latter excites thirst and spoils the natural flavour of the food. It is the custom, especially in restaurants, to add a large quantity of salt to pulse, savoury food, potatoes and soups. Bakers' brown bread is usually very salt, and sometimes white is also. In some persons much salt causes irritation of the skin, and the writer has knowledge of the salt food of vegetarian restaurants causing or increasing dandruff. As a rule, fondness for salt is an acquired taste, and after its discontinuance for a time, food thus flavoured becomes unpalatable.
Organic Compounds are formed by living organisms (a few can also be produced by chemical means). They are entirely decomposed by combustion.
The Non-Nitrogenous Organic Compounds are commonly called carbon compounds or heat-producers, but these terms are also descriptive of the nitrogenous compounds. These contain carbon, hydrogen and oxygen only, and furnish by their oxidation or combustion in the body the necessary heat, muscular and nervous energy. The final product of their combustion is water and carbon dioxide (carbonic acid gas).
The Carbohydrates comprise starch, sugar, gum, mucilage, pectose, glycogen, &c.; cellulose and woody fibre are carbohydrates, but are little capable of digestion. They contain hydrogen and oxygen in the proportion to form water, the carbon alone being available to produce heat by combustion. Starch is the most widely distributed food. It is insoluble in water, but when cooked is readily digested and absorbed by the body. Starch is readily converted into sugar, whether in plants or animals, during digestion. There are many kinds of sugar, such as grape, cane and milk sugars.
The Oils and Fats consist of the same elements as the carbohydrates, but the hydrogen is in larger quantity than is necessary to form water, and this surplus is available for the production of energy. During their combustion in the body they produce nearly two-and-a-quarter times (4 : 8.9 = 2.225) as much heat as the carbohydrates; but if eaten in more than small quantities, they are not easily digested, a portion passing away by the intestines. The fat in the body is not solely dependent upon the quantity consumed as food, as an animal may become quite fat on food containing none. A moderate quantity favours digestion and the bodily health. In cold weather more should be taken. In the Arctic regions the Esquimaux consume enormous quantities. Nuts are generally rich in oil. Oatmeal contains more than any of the other cereals (27 analyses gave from 8 to 12.3 per cent.)
The most esteemed and dearest oil is Almond. What is called Peach-kernel oil (Oleum Amygdal? Persic?), but which in commerce includes the oil obtained from plum and apricot stones, is almost as tasteless and useful, whilst it is considerably cheaper. It is a very agreeable and useful food. It is often added to, as an adulterant, or substituted for the true Almond oil. The best qualities of Olive oil are much esteemed, though they are not as agreeable to English taste as the oil previously mentioned. The best qualities are termed Virgin, Extra Sublime and Sublime. Any that has been exposed for more than a short time to the light and heat of a shop window should be rejected, as the flavour is affected. It should be kept in a cool place. Not only does it vary much in freedom from acid and rancidity, but is frequently adulterated. Two other cheaper oils deserve mention. The "cold-drawn" Arachis oil (pea-nut or earth-nut oil) has a pleasant flavour, resembling that of kidney beans. The "cold-drawn" Sesamé oil has an agreeable taste, and is considered equal to Olive oil for edible purposes. The best qualities are rather difficult to obtain; those usually sold being much inferior to Peach-kernel and Olive oils. Cotton-seed oil is the cheapest of the edible ones. Salad oil, not sold under any descriptive name, is usually refined Cotton-seed oil, with perhaps a little Olive oil to impart a richer flavour.
The solid fats