Food study

The non-volatile fats of food are chiefly three : olein, palmitin, and stearin. The first of these has so low a melting point that it is an oil at ordinary temperatures. Olive and cottonseed oils are largely composed of olein. Stearin has the highest melting point of the three, and so fats like suet, which is largely stearin, are fairly firm. The melting point of palmitin is between that of the other two. Most of the fat of foods is a mixture of these nonvolatile fats. The melting point of some of them is shown in the following table : Stearin . ... .. .,:. 140° F. Lard 86-102° Mutton fat . . . 116.5-123° Butter 83-95° Palmitin .... 113° Olein Fluid Beef fat .... 107.5-122° Olive oil Fluid Bacon f at . . . . 103° Cottonseed oil ... Fhiid Fats which have a melting point of 110° or below, seem to be digested about equally well. However, the eating of fat causes the food to remain longer in the stomach and so retards the processes of digestion. In some cases this may FATS 261 cause digestive disturbances by allowing more time for the decomposition of food in the digestive tract through the action of bacteria, but fat itself is not liable to objectionable decomposition during digestion. Fat which has been heated to too high a temperature is much more liable to cause digestive difficulties, because, apparently, of the presence of irritating decomposition products. Hence it is necessary in selecting a fat for frying to consider the temperatures at which this decomposition takes place. The following is a table of "cracking points", as the decomposition temperatures are often called : Crisco 396° F. Lard 419-475° Olive oil .... 608-680° Butter 365-428° Cottolene .... 450° Fats vary greatly in cost, olive oil being expensive. Advantage should be taken of the lower price asked for it in quantity. (Buying oil in a small bottle is very extravagant.) Italian oil in bulk is usually cheaper than French oil. Good American oil is manufactured in California. Butter and cream are also expensive sources of fat, but they are very desirable for children and invalids on account of their ease of digestion. Bacon fat ranks with butter and cream both in digestibility and expense. Fat left from the frying of bacon should be carefully saved for sauteing, as should that tried out from the fat of beef, veal, pork, and chicken. Even the fat which hardens on soup stock can be used. Gravies, sauces, cream soups, and gingerbread may all be made with such fat, and vegetables and meat may be sauted in them. Mutton fat * has so strong a flavor that it is usually objected to on this account. 1 For ways of utilizing this fat, see U. S. Dept. of Agriculture, Bulletin No. 310, page 11. Yolks of eggs are one-third fat and furnish fat in a very digestible form. U. S. Dept. of Agriculture. Bulletin No. 310. "Digestibility of Some Animal Fats." 1. How are these fats obtained : butter, lard, cottonseed oil, olive oil, beef fat, lard, Crisco ? 2. What does each cost per pound? Are fats sufficiently expensive foods to make it worth while to consider economy in their use ? 3. Suggest good opportunities for the substitution of a cheaper fat for a more expensive one. For example, would it be better to use lard in gingersnaps or sugar cookies ? 4. Discuss the digestibility of fats.