PROCESSES INVOLVED IN MAKING STOCK.
Although the making of stock or soup is a simple process, it must necessarily be a rather long one. The reason for this is that all flavors cannot be drawn from the soup materials unless they are subjected to long, slow cooking at a temperature lower than the boiling point. With this point definitely understood, the actual work of soup making may be taken up.
When clear stock is to be made from fresh meat, the required quantity of meat should be cut into small pieces so as to expose as much of the surface as possible from which the flavor of the meat can be drawn. A little more flavor is obtained and a brown color developed if a small part, perhaps a fourth, of the pieces of meat is first browned in the frying pan. The pieces thus browned, together with the pieces of fresh meat, are put into a kettle and a quart of cold water for each pound of meat is then added.
The reason for using cold rather than hot water will be evident when the action of water on raw meat is understood. The fiber of meat is composed of innumerable thread-like tubes containing the flavor that is to be drawn out into the water in order to make the stock appetizing. When the meat is cut, these tiny tubes are laid open. Putting the meat thus prepared into cold water and allowing it to heat gradually tend to extract the contents of the tubes. This material is known as extractives and it contains in its composition stimulating substances. On the other hand, plunging the meat into hot water and subjecting it quickly to a high temperature will coagulate the protein in the tissue and prevent the extractives from leaving the tubes.
To obtain the most flavors from meat that is properly prepared, it should be put over a slow fire and allowed to come gradually to the boiling point. As the water approaches the boiling point, a scum consisting of coagulated albumin, blood, and foreign material will begin to rise to the top. This should be skimmed off at once and the process of skimming must be continued until no scum remains. When the water begins to boil rapidly, the fire should be lowered so that the water will bubble only enough for a very slight motion to be observed. Throughout the cooking, the meat should not be allowed to boil violently or to cease bubbling entirely.
The meat should be allowed to cook for at least 4 hours, but longer if possible. If, during this long cooking, too much water evaporates, more should be added to dilute the stock. The salt that is required for seasoning may be added just a few minutes before the stock is removed from the kettle. However, it is better to add the salt together with the other seasonings after the stock has been drawn off, for salt, has a tendency to harden the tissues of meat and to prevent the flavor from being readily extracted.
Although, as has been explained, flavor is drawn from the fibers of meat by boiling it slowly for a long time, the cooking of meat for soup does not extract the nourishment from it to any extent. In reality, the meat itself largely retains its original nutritive value after it has been cooked for soup, although a small quantity of protein is drawn out and much of the fat is removed. This meat should never be wasted; rather, it should be used carefully with materials that will take the place of the flavor that has been cooked from it.
A greasy soup is always unpalatable. Therefore, a very important feature of soup making, whether a thin or a thick soup is being made, is the removal of all grease. Various ways of removing grease have been devised depending on whether the soup is hot or cold. In the case of hot or warm soup, all the grease that it is possible to remove with a spoon may be skimmed from the top and the remainder then taken up with a piece of clean blotting paper, tissue-paper or absorbent cotton. Another plan by which the fat may be hardened and then collected, consists in tying a few small pieces of ice in a piece of cloth and drawing them over the surface of the soup. A very simple method is to allow the soup or stock to become cold, and then remove the fat, which collects on the top and hardens, by merely lifting off the cake that forms.
Sometimes it is desired to improve the appearance of soup stock particularly a small amount of soup that is to be served at a very dainty luncheon or dinner. In order to do this, the stock may be treated by a certain process that will cause it to become clear. After being cleared, it may be served as a thin soup or, if it is heavy enough, it may be made into a clear, sparkling jelly into which many desirable things may be molded for salad or for a dish to accompany a heavy course. Clearing soup is rather extravagant; however, while it does not improve the taste, it does improve the appearance.
A very satisfactory way in which to clear stock is to use egg whites and crushed eggshell. To each quart of cold stock should be added the crushed shell and a slightly beaten egg white. These should be mixed well, placed on the fire, and the mixture stirred constantly until it boils. As the egg coagulates, some of the floating particles in the stock are caught and carried to the top while others are carried to the bottom by the particles of shell as they settle. After the mixture has boiled for 5 or 10 minutes, the top should be skimmed carefully and the stock then strained through a fine cloth. When it has been reheated, the cleared stock will be ready to serve.
Although thin, clear soups are preferred by some and are particularly desirable for their stimulating effect, thick soups find much favor when they are used to form a substantial part of a meal. Besides giving consistency to soup, thickening usually improves the flavor but its chief purpose is to give nutritive value to this food. In fact, whenever a soup is thickened, its food value is increased by the ingredient thus added. For this reason, it is advisable to thicken soups when they are desired for any other purpose than their stimulating effect.
The substance used to thicken soups may be either a starchy material or food or a puree of some food. The starchy materials generally used for this purpose are plain flour, browned flour, corn starch and arrowroot flour. Any one of these should be moistened with enough cold water to make a mixture that will pour easily and then added to the hot liquid while the soup is stirred constantly to prevent the formation of lumps. A sufficient amount of this thickening material should be used to make a soup of the consistency of heavy cream.
The starchy foods that are used for thickening include rice, barley, oatmeal, noodles, tapioca, sago and macaroni. Many unusual and fancy forms of macaroni can be secured or the plain varieties of Italian pastes may be broken into small pieces and cooked with the soup. When any of these foods are used, they should be added long enough before the soup is removed to be cooked thoroughly.
Purees of beans,
peas, lentils, potatoes and other vegetables are especially desirable for the
thickening of soups, for they not only give consistency, but add nutritive value
and flavor as well. Another excellent thickening may be obtained by beating raw
eggs and then adding them carefully to the soup just before it is to be served.
After eggs have been added for thickening, the soup should not be allowed to
boil, as it is liable to curdle.