Boiling

This process was originally carried on by placing food in a hole in clay, in a hollow piece of wood, stone mortar or dish, or a clay dish, the heat being furnished by hot stones dropped into the water. With the invention of pottery and metal dishes that would stand the effects of fire, boiling is more conveniently carried out by a fire beneath the receptacle.

By a curious paradox the juices of roasted or baked meats may actually boil, whereas, owing to heat conduction, those of boiled meats, practically never do. It is possible only to raise the temperature in water up to the critical point at which steam is formed, and in ordinary cooking, the interior of the mass of meat does not usually rise much above 170. It is commonly stated that, at high altitudes, eggs, etc., cannot be boiled hard on account of the lowering of the critical boiling temperature, but, as human life cannot exist where the boiling point, on account of lessened atmospheric pressure, is beneath the temperature at which albumin coagulates, this statement is incorrect.

In boiling, some of the salts and flavoring matters of food are extracted; hence the water used should be as little as is required to surround and cover the meat, although fish are usually cooked in a larger quantity, relatively, than meats. In order to minimize the waste, boiling, like roasting and baking, requires a high initial temperature, the meat being placed in water already boiling, and the boiling being maintained vigorously for five minutes, so as to coagulate the albumin of the surface. Then the temperature is lowered. In this process the juices of the meat are Squeezed out, the loss being about the same as for baking-unless the boiling is prolonged.

Boiling is applied also to a great variety of vegetables, especially when a mingling of flavors is desired. Certain vegetables, such as peas, beans, asparagus, etc., when cooked alone, or in simple combination as succotash (corn with about 1/3 as much beans) are often served without draining, so that very little water should be used in the process. Dressings of butter or butter and milk, with or without flour, etc., for thickening, may be used.

The Indians have a most delicious method of boiling corn. The corn is cut from the ear, replaced in the husks which are carefully closed so as to be almost water-tight, and, if the process has been properly carried out, the corn is tender and well-flavored and not watery.

Stewing is carried out at a lower temperature than boiling - 135 - 160 F., so as to avoid coagulating albumin. It is applied to various meats and vegetables, often combined, and the extracted nutriment is served with the partially extracted residue. A stew is virtually a thick soup. In so far as the ingredients of both the extract and the residue, are easily digested or are harmless, stews may be employed for invalids, but if greasy, or if rich sauces are added, or if the residue is mechanically indigestible and irritating, it is obviously better to use either nourishment extracted by cooking or nourishment properly prepared in the original food mass. Stewing is the most oeconomic method of cooking, as nothing is lost.

Soups and Broths consist of soluble nutriment, disintegrated shreds of the original food and various ingredients added. A meat broth prepared at a temperature above 160 F., the coagulation point of albumin, contains salts, extractives, which are mainly excrementitious. and a little gelatin, also some melted fat. although the last is often skimmed off to make the broth more pleasing and palatable. In so far as protein is concerned, a meat tea made by boiling cannot be more nourishing than egg tea. that is to say, the water in which eggs are poached, or in plain words, it contains no protein nourishment at all. and is - barring certain qualitative and quantitative differences - of the same dietetic value as urine. Such teas are usually appetizing, and on account of the xanthin-compounds, stimulating in much the same way as coffee, but unless shreds of boiled meat are allowed to remain in the tea, or some other nutriment is added, the gelatin and traces of carbohydrate and fat constitute their sole organic nutriment, and these are not enough to be considered.

A considerable but variable proportion of protein may be extracted by gentle simmering at a temperature considerably below 160 F., the exact amount of nutriment being determined only by analysis but usually being less than 5%.

Different kinds of soups range all the way from meat teas to meat and vegetable stews, with due allowance for straining or skimming on the one hand, or addition of flour, milk, butter, noodles, vermicelli, etc., on the other. Their nutritive value, therefore, cannot be determined, except by analysis or careful study of the individual composition.

The most concentrated meat broth or soup, involves pre-digestion. The meat is finely minced, and dilute hydrochloric acid is gradually added to saturation (See table, Chapter VIII (Predigestion Of Foods).) so as to convert the albumin into syntonin. This is extracted by soaking in cold water for several hours. The extract may be eon-ccncentrated by evaporation at 130 F., so as to form a liquid containing about 50% of the meat albumin, or it may still further be concentrated to a jelly.

Braising is a method of stewing in which various vegetables are boiled, and the meat is added at a lower temperature, evaporation being largely prevented by using a covered pot. The liquid should barely cover the meat and the pot should be relatively small. Sherry and various spices are often added.

Frying is convenient on account of the portability of the apparatus and may be applied to both meats and vegetables, even to cereal preparations, such as mush and fritters. In so far as it is applied to clear fats, it may be used even for invalids, providing that the fat itself is not objectionable. Fat has nearly the same boiling point as water, and the process is much the same as boiling. In order to prevent the penetration of fat, the latter should be hot before the meat or other substance is placed in it. In such cases, if the outer coating of dense and fat-impregnated meat or other food is removed, there is no special objection to its employment even for invalids. As in boiling, the fat, including butter, olive or other oil should, theoretically, envelope the entire food mass, otherwise frying is virtually a combination of boiling and baking. If the fat is burned, i. e., reaches a temperature much above boiling, various disagreeable and harmful by-products are formed.

Generally speaking, double cooking is not available for invalids, warmed up meats especially being liable to be tainted and being rendered tough. However, tough meats may be rendered tender by parboiling before baking and boiled potatoes, baked bread and other cereals, may be further roasted or toasted with advantage. So, too, vegetables and meats already cooked, may be made into purees with cooked flour dressing.