COOKING
The cooking of food is as important as its selection, because the manner of cooking makes it easier or more difficult of digestion. The question of the proper selection and cooking of food is so vital to the health and resultant happiness of every family, and to the strength and well being of a nation, that every woman, to whom the cooking for a family is entrusted, should have special preparation for her work, and every girl should be given practical and theoretical training in Dietetics in our public schools. The study is as dignified as the study of music and art. Indeed it can be made an art in the highest conception of the term. Surely the education of every girl in the vocation, in which she sooner or later must engage, either actively or by directing others, means more than education in music and drawing. We must all eat two and three times every day; there are few things which we do so regularlyand which are so vital; yet in the past we have given this subject less study than any common branch in our schools. When the dignity of the profession of dietetics is realized, the servant problem will be largely solved.
In cooking any food, heat and moisture are necessary, the time varying from thirty minutes to several hours, according to different foods. Baked beans and meats containing much connective tissue, as boiling and roasting cuts, require the longest time.
The purposes in the cooking of foods are: the development of the flavor, which makes the food appetizing, thus encouraging the flow of gastric juice; the sterilization, thereby killing all parasites and micro-organisms, such as the tape worm in beef, pork, and mutton, and the trichinae in pork; the conversion of the nutrients into a more digestible form, by partially or wholly converting the connective tissue into gelatin.
Cooking of Meats
The fundamental principle to be observed in the cooking of meat concerns the retention of the juices, since these contain a large part of the nutrition. The heat develops the flavor,and the moisture, together with the heat, dissolves the connective tissue and makes it tender.
A choice piece of meat may be toughened and made difficult of digestion, or a tough piece may be made tender and easy to digest, by the manner of cooking.
Soups.To make meat soups, the connective tissue, bone and muscle should be put into cold water, broughtslowlyto the boiling point and allowed to simmer for hours. It must be remembered that the gelatin from this connective tissue does not contain the tissue building elements of the albuminoids. These are retained in what meat may be about the bones of the boiling piece and in the blood.
The albumin of meat is largely in the blood and it is the coagulated blood which forms the scum on soup, if heated above a certain point; the cook should boil the soup slowly, or much of the nutrition is lost in the coagulated blood, or skum.
Roasting.The flavor and juice of the meat is best retained by roasting. If it is put into a hot oven, with a little suet over the top, so as to sear the meat with hot fat, and no water is put in the pan, it willretain the juice and the flavor. Water draws out the extractives.
It is important to remember that the smaller the cut to be roasted, the hotter should be the fire. An intensely hot fire coagulates the exterior and prevents the drying up of the meat juice. After the surface is coagulated and seared it should cook slowly.
Unless the oven is sufficiently hot to sear the surface, the moisture, or juice, will escape into the roasting pan and the connective tissue will be toughened. A roast should be cooked in a covered roaster to retain the moisture.
The roast should be turned as soon as one side is seared and just sufficient water put into the pan to keep it from burning.
Frequent basting of a roast, with the fat, juice, and water in the roasting pan, still further sears the surface, so that the juices do not seep through and keeps the air in the pan moist; the heated moisture materially assists in gelatinizing the connective tissue,—roasting pans are now made which are self-basting.
Broiling.The same principle applies to broiling as to roasting. The meat is put over a very hot flame and turned so as toquickly sear both sides, to prevent the juice from oozing out. In fact, the best broiled steaks are turned just as soon as the juice begins to drip, so as to retain all juice in the meat.
Meat containing much connective tissue is not adapted to broiling, because it takes too long for this tissue to become gelatinized.
Steak broiled in a skillet, especially round steak which has been pounded to assist in breaking the connective tissue, is often first dipped in seasoned flour, which is rubbed well into it. The flour absorbs the meat juices so that none of them are lost. All meats broiled in skillets should be put into a very hot skillet and one surface seared, then should be turned so as to sear the other side. The skillet should be kept covered so as to retain the moisture.
Boiling.In boiling meat, where the object is to eat the tissue itself, it should be put into hot water, that the albumin on the surface may be immediately coagulated and prevent the escape of the nutrients into the water. It is impossible to make a rich broth and to have a juicy, highly flavored piece of boiled meat at thesame time. Meat is best roasted or broiled when the meat tissue is to be eaten.
The boiling cuts contain more connective tissue, therefore they require a much longer time to cook in order to gelatinize this tissue. They are not as rich in protein as the steaks.
Meat soups, bouillons and broths contain very little nutriment, but they do contain the extractives, and the flavors increase the flow of digestive juices and stimulate the appetite. It is for this reason that soups are served before a meal rather than for a dessert; they insure a copious flow of gastric juice and saliva to act upon the crackers or toast eaten with the soup. Many mistake the extractives and flavor for nourishment, feeling that the soups are an easy method of taking food, but the best part of the nutriment remains in the meat or vegetables making the soup.
Pot Roasts.In the case of a pot roast, or roast in a kettle, where it is desirable to use both the fibre of the meat and the juice, or gravy, it should be put into a little cold water and raised to about 180 degrees F., where it should be kept for some hours. The juices of the meat seep out in thegravy. The extractives are simmered down and are again poured over the meat in the rich gravy.
Frying.This is the least desirable method of cooking. Food cooked by putting a little grease into a frying pan, such as fried potatoes, mush, eggs, french toast, and griddle cakes, are more difficult of digestion than foods cooked by any other means, particularly where the fat is allowed to smoke. The fat is superheated; if a lighted match is placed near the smoke it will catch fire, showing that it is volatilizing, or being reduced to a vapor.
The extreme heat liberates fatty acids. This acrid fat soaks into the food and renders it difficult of digestion. It is wise not to employ this method of cooking.
The objection to frying does not hold so strongly in the case of vegetables, such as potatoes, if friedslowlyin fat, that is not over heated, or to griddle cakes cooked slowly without smoke, or to foods immersed in grease (such as saratoga chips, doughnuts, french fried potatoes, etc.), as the large amount of fat does not permit it to get so heated. It does apply, however, if the fat is sufficiently heated to smoke.
The coating of vegetables and cereals with the hot fat prevents the necessary action of saliva upon the starch globules. As previously stated, most of the starches are digested in the mouth and the stomach, while the fats are not emulsified until they reach the intestines.
The starch globules in cereals and vegetables are in the form of cells, the covering of these cells being composed largely of nitrogenous matter. The protein is not acted upon by the saliva, and the nitrogenous matter is largely digested in the stomach. It is more easily dissolved if it is broken or softened by cooking, so that the carbohydrates can come in contact with the saliva, but if encased in fried fat, the gastric juices cannot digest the protein covering and the saliva cannot reach the starch until the fat is emulsified in the intestines. This means that wherever starch globules are surrounded with fat, the digestive ferments reach these globules with difficulty and fried foods must be digested mostly in the intestines.
Fats are readily absorbed in their natural condition, but when subject to extreme heat, as in frying, they are irritants. For this reason, eggs, poached, boiled or baked are more easily digested than fried.
Boiling, broiling and roasting are preferable to foods cooked in fats.
Cooking of Cereals
One safe rule for the cook is, that it is better to cook most foods too much than too little; overcooking is uncommon and harmless, whileundercooked foods are common and difficult of digestion.
In partially cooked cereals, one does not know how much of the cooking has been done, but it is safe to cook all such foods at least as long as specified in the directions.
One reason why breakfast foods, such as rolled oats, are partially cooked, is because they keep longer.
As has been stated, the nutrients of the grain are found inside the starch-bearing and other cells, and the walls of these cells are made of crude fiber, on which the digestive juices have little effect. Unless the cell walls are broken down, the nutrients can not come under the influence of the digestive juices until the digestive organs have expended material and energy in trying to get at them. Crushing the grain in mills, and making it still finer by thorough mastication breaks many of the cell walls, and the action of the saliva and other digestivejuices also disintegrates them more or less, but the heat of cooking accomplishes the object much more thoroughly. The invisible moisture in the cells expands under the action of heat, and the cell walls burst. The water added in cooking also plays an important part in softening and rupturing them. Then, too, the cellulose itself may be changed by heat to more soluble form. Heat also makes the starch in the cells at least partially soluble, especially when water is present. The solubility of the protein is probably, as a rule, somewhat lessened by cooking, especially at higher temperatures. Long, slow cooking is therefore better, as it breaks down the crude fiber and changes the starch to soluble form without materially decreasing the solubility of the protein.
“In experiments made with rolled oats at the Minnesota Experiment Station, it appeared that cooking (four hours) did not make the starch much more soluble. However, it so changed the physical structure of the grains that a given amount of digestive ferment could render much more of it soluble in a given time than when it was cooked for only half an hour.
“On the basis of the results obtained, the difficulty commonly experienced in digestingimperfectly cooked oatmeal was attributed to the large amounts of glutinous material which surrounds the starch grains and prevent their disintegration. When thoroughly cooked the protecting action of the mucilaginous protein is overcome, and the compound starch granules are sufficiently disintegrated to allow the digestive juices to act. In other words, the increased digestibility of the thoroughly cooked cereal is supposed to be largely due to a physical change in the carbohydrates, which renders them more susceptible to the action of digestive juices.”
Pastry.Pastry owes its harmful character to the interference of fat as shown on page198, with the proper solution of the starch,—at least such pastry as requires the mixing of flour with fat; the coating of these granules with fat prevents them from coming in contact with liquids; the cells cannot absorb water, swell and burst so that they may dissolve. The fat does not furnish sufficient water for this and so coats the starch granules as to prevent the absorption of water in mixing, or of the saliva in mastication. This coating of fat is not relieved until late in the process of digestion, or until the foodreaches the intestines. This same objection applies to rich gravies, unless the flour be dissolved in water and heated before being mixed with the fats. The objection, therefore, is to such pastry as is made by mixing flour with fat, as in pie crust; it does not apply to most puddings.
Heat, in cooking, causes a combustion of the carbonic acid gas and the effort of this gas to escape, as well as the steam occasioned by the water in the food, causes the bubbles. When beaten eggs are used, the albuminoids in the bubbles expand the walls, which stiffen with the heat and cause the substances containing eggs to be porous.
Cooking of Vegetables
Since the root vegetables contain a large proportion of carbohydrates, they should be well cooked, in order that the cells may be fully dissolved, and the crude fibre broken.
Vegetables are best cooked in soft water, as lime or magnesia, the chemical ingredients which make water “hard”, make the vegetables less soluble.
Vegetables and fruits become contaminated with the eggs of numerous parasites from the fertilizers used; hence they should be thoroughly washed.
The objection to frying meats are equally strong in regard to vegetables. The coating of vegetables with the hot fat retards digestion, as shown on page198.
Cooking of Fruit
“In different countries opinions differ markedly regarding the relative wholesomeness of raw and cooked fruit. The Germans use comparatively little raw fruit and consider it far less wholesome than cooked fruit. On the other hand, in the United States raw fruit of good quality is considered extremely wholesome, and is used in very large quantities, being as much relished as cooked fruit, if indeed it is not preferred to it. It has been suggested that the European prejudice against raw fruit may be an unconscious protest against unsanitary methods of marketing or handling and the recognition of cooking as a practical method of preventing the spread of disease by fruit, accidentally soiled with fertilizers in the fields or with street dust.
“As in the case with all vegetable foods, the heat of cooking breaks down the carbohydrate walls of the cells which make up the fruit flesh, either because the moisture or other cell contents expand and rupture the walls or because the cell wall is itselfsoftened or dissolved. Texture, appearance, and flavor of fruit are materially modified by cooking, and, if thorough, it insures sterilization, as in the case of all other foods. The change in texture often has a practical advantage, since it implies the softening of the fruit flesh so that it is more palatable and may be more readily acted upon by the digestive juices. This is obviously of more importance with the fruits like the quince, which is so hard that it is unpalatable raw, than it is with soft fruits like strawberries. When fruits are cooked without the addition of water or other material, as is often the case in baking apples, there is a loss of weight, owing to the evaporation of water, and the juice as it runs out carries some carbohydrates and other soluble constituents with it, but under ordinary household conditions this does not imply waste, as the juice which cooks out from fruits is usually eaten as well as the pulp. Cooking in water extracts so little of the nutritive material present that such removal of nutrition is of no practical importance.
“The idea is quite generally held that cooking fruit changes its acid content, acid being sometimes increased and sometimesdecreased by the cooking process. Kelhofer showed that when gooseberries were cooked with sugar, the acid content was not materially changed, these results being in accord with his conclusions reached in earlier studies with other fruits. The sweeter taste of the cooked product he believed to be simply due to the fact that sugar masks the flavor of the acid.
“It is often noted that cooked fruits, such as plums, seem much sourer than the raw fruit, and it has been suggested that either the acid was increased or the sugar was decreased by the cooking process. This problem was studied by Sutherst, and, in his opinion, the increased acid flavor is due to the fact that cooked fruit (gooseberries, currants, plums, etc.) usually contains the skin, which is commonly rejected if the fruit is eaten raw. The skin is more acid than the simpler carbohydrates united to form a complex carbohydrate. In some fruits, like the apple, where the jelly-yielding material must be extracted with hot water, the pectin is apparently united with cellulose as a part of the solid pulp. As shown by the investigations of Bigelow and Gore at the Bureau of Chemistry, 40 per cent of the solid material of apple pulpmay be thus extracted with hot water, and consists of two carbohydrates, one of which is closely related to gum arabic. That such carbohydrates as these should yield a jelly is not surprising when we remember that they are similar to starch in their chemical nature, and, as every one knows, starch, though insoluble in cold water, yields when cooked with hot water a large proportion of paste, which jellies on cooling.
“When fruits are used for making pies, puddings, etc., the nutritive value of the dish is, of course, increased by the addition of flour, sugar, etc., and the dish as a whole may constitute a better balanced food than the fruit alone.”[8]
FOOTNOTES:[8]C. F. Langworthy, Ph. D.—In charge of Nutritive Investigations of the United States Experiment Station.
[8]C. F. Langworthy, Ph. D.—In charge of Nutritive Investigations of the United States Experiment Station.
[8]C. F. Langworthy, Ph. D.—In charge of Nutritive Investigations of the United States Experiment Station.