- Food and Cooking
Methods of Cooking
Cookery, the art of preparing food by the application of heat. The methods of cookery involve gentle to intense heat, wet or dry, and vary in application from natural fires to complicated technological instruments.
Effect of Cooking on Food
Cooking makes many foods, such as tough meats and starchy vegetables, easier to eat, and often improves the taste. It may also make food more easily digestible. Certain vegetables, such as cassava (from which tapioca is made) are poisonous if eaten raw, but safe after cooking. Cooking stops the action of enzymes and sterilizes the outside of the food particles, thus aiding in preservation. The method of cooking must be appropriate for the type and quality of the food in order to enhance its flavor and texture. All cooking destroys some of the nutrient value of natural food, especially the vitamins. Cooking also creates new foods, such as cakes and puddings.
Methods of Cooking
The choice of the most suitable method of cooking is fundamental to achieving the most palatable results. The methods of cooking can be classified according to the method of heat transfer to the food: conduction, convection, or radiation. Conduction of heat is used when cooking in a liquid medium. These methods (boiling, stewing, braising, pot-roasting, and pressure cooking) are most suitable for food that requires the penetration of water to soften or tenderize the structure of the food, for example, tough meat or vegetables with a high cellulose content. Convection of heat is used in steaming and baking. These methods are most suitable for tender foods that will cook by heat transmitted through the food. Radiant heat is used in grilling, infrared grilling, barbecuing, roasting (traditionally spit-roasting over an open fire) and microwave cooking. These methods, with the exception of microwave, are only suitable for tender foods, as the intense heat coagulates and denaturises the protein, causing a toughening of the structure.
Broiling or grilling, probably the earliest known process of cooking meat, consisted in exposing the surface to direct heat, so that the outside of the meat was well browned, and the inside rendered tender and juicy. The primitive method of broiling meat was by burying it in hot ashes. The meat is turned during broiling by a pair of tongs, as a fork would cause the juices to escape. Small birds, such as quails, may be excellently broiled in about 10 minutes; white meat as a rule requires longer cooking than red. This method is only suitable for very tender cuts.
Roasting is really the application of the principles of broiling to larger joints of meat, for which it is an economical process and one producing excellent results. As in broiling, exposure to the greatest heat should come at the beginning of the cooking, so that the meat juices are sealed in and the joint, when cut, exudes a rich, reddish gravy. The interior of the joint should then be allowed to cook in a rather gentler heat, by means of which the fibres are loosened, the connective tissue is changed into gelatin, the fibrin and albumin are oxidized, and the fat cells broken. The fat and tissues on the surface of the meat become caramelised and browned, and acquire a distinctive odor and flavor. The joint should be frequently basted with melted fat in order to prevent evaporation of the watery portion of the meat juice. The time required for roasting is from 15 to 30 minutes for each pound of meat, white meat taking longer than red. Meat can be roasted in a thick saucepan by melting sufficient fat to cover the bottom, and when hot putting in the meat, browning it on all sides, covering with a lid, and continuing to cook over a low heat.
Baking is now the usual way of roasting meat in an oven. It is placed in an open tin and heat applied all round at once, rather than to one side at a time. Baking is also applied to other kinds of food besides meat. Fish can either be wrapped entirely in greased paper or foil, so retaining all the flavor, or laid in a greased casserole, with dabs of fat placed on top. Pies containing either meat or fruit are usually baked. All forms of pastry are baked, and require a hot oven. Special care should be taken to close the oven door gently during the early stages of cake baking, or the risen mixture may collapse. Cakes require a wide range of temperature. Plain cakes and scones are baked at a high temperature; rich cake mixture and gingerbreads are baked at a lower temperature. Similarly the initial cooking temperature for plain yeast mixtures is high, wide richer varieties are baked at lower temperature. Milk puddings are baked in a slow oven.
Stewing is the slow cooking of food in a little liquid in a closed vessel. It is the method recommended for tough, fibrous meat; various other ingredients, such as root vegetables and herbs, may be added to the meat and cooked together with it. Since none of the constituents of the materials used can escape, stewing is a most economical method of cooking, and is rendered doubly so by the fact that coarse and tough meat may be made palatable, tender and digestible by this means. Success depends on keeping the temperature below about 90 °F. Lean meat is best for stewing; it should be cut into small pieces and slightly browned by frying in fat before being placed in the stewpan. It should then be covered with water or stock, and set to cook for several hours, particular care being taken to prevent boiling, so that the albumin does not harden, and the meat cooks in its own gradually extracted juices. The principle of stewing is also employed in the making of broth or soup and stock. Meat and bones for the making of soup should be placed in cold water and gradually raised to boiling point, so that the escape of meat juices into the liquid is not hindered by hardening of the albumin. Since, however, the solid constituents are not eaten, bone stock is boiled slowly for several hours in order to extract the gelatinous matter. It is.this gelatine which causes soup to form a jelly when cold, but contrary to belief it has no great food value. Vegetable water or vegetable stock also makes a good basis for soups. Stewing is also a common method of cooking fruit, by making a syrup of sugar dissolved in warm water, and adding the fruit, which is cooked gently, but not boiled.
Braising is a combination of stewing and baking, or pot roasting. It is an excellent method of cooking meat, because the cheaper cuts or tougher joints become tender after being treated this way. The meat is fried, after removing the surplus fat, in a small quantity of hot fat for a few minutes until the covering is sealed and browned all over, and then it is removed from the pan. A liberal quantity of sliced root vegetables is lightly fried in the fat, and then placed in a saucepan or casserole, with water or stock half covering them; seasoning and herbs are added. The meat is then placed on top of the vegetables, and the saucepan or casserole covered with a lid; the contents being cooked over a low heat or in a slow oven for several hours. Poultry, game and root vegetables may also be cooked this way.
Boiling is cooking by immersion in boiling water. Coagulation of proteins, as in the case of the egg, takes place at about 90°C, and an egg cooked at this temperature is more easily digested than one kept at boiling point. The usual method of cooking eggs by boiling is far from ideal, as it allows the albuminous white to become overcooked while leaving the yolk underdone. A much better plan is to place the eggs in boiling water and leave them in gradually cooling water for about 20 minutes. This method can also be applied to fish, but to retain the flavor steaming or baking is preferable. Certain semi-liquid foods, such as milk puddings, jams and jellies, are cooked by boiling the substance itself, constant stirring being necessary in such cases to prevent burning.
Steaming, in which the food is placed in a covered vessel having a perforated bottom which fits tightly over a saucepan of boiling water, takes rather longer than boiling, but is preferable in many ways, giving a finer flavor, and preventing the surface of puddings from becoming sodden through contact with water. It is the most suitable method for fragile foods that may break in boiling water.
Conservative cookery is the method recommended for vegetables, as only a little water is used and the flavor and vitamins are retained, or conserved. Green vegetables should be shredded coarsely and put into very little boiling water, covered with a lid, and tossed occasionally to prevent burning. Attention is needed during this method of cooking, which does not take more than 10 to 15 minutes. The vegetables should be removed from the heat immediately they are cooked, and eaten at once. When cooking spinach it is unnecessary to add any water. A teaspoonful of fat may be added during, or after, cooking the vegetables. Carrots are delicious sliced and sauteed (i.e. cooked in a little hot fat) for a few minutes, a tablespoonful of water added, and then cooked for about ten minutes in a covered pan. Vegetables are more appetizing and nutritious when cooked conservatively than by the method of boiling them in plenty of water.
Potatoes are more nutritious when cooked in their skins, after being well scrubbed. They can be boiled gently or baked in the oven. The reason for cooking potatoes in their jackets is that the layer nearest the skin is considerably richer in mineral matter and protein than the outer flesh and central core; and the flavor is enhanced when potatoes are cooked this way. Vegetable water should not be thrown away, but used for soup or gravy.
Frying, or cooking by hot fat, is of two kinds, wet and dry. The former, which is much the preferable, is done in a deep frying pan containing lard, butter, dripping or cooking oil. The fat should be gradually heated until it gives off a faint bluish vapor; the articles to be fried are then immersed, being usually enclosed in a wire basket for ease in handling. Fried food should be crisp, golden-brown in color, and non-greasy, any superfluous fat on the surfaces being removed by placing the articles on absorbent paper. Fish, cutlets, croquettes, fritters, and potatoes are delicious when well cooked in this way, and many foods are, for this method of cooking, first rolled in beaten egg and breadcrumbs or in batter. Dry frying is performed in a shallow frying-pan the bottom of which is covered with hot fat. It has many disadvantages; the food is apt to be unequally cooked, greasy and charred, and has to be constantly turned. Bacon, sausages and chops, are cooked thus in their own escaping fat, while eggs, cold potatoes and pancakes may be dry fried in a little dripping or lard. This method of frying is also known as sauteing. All fried food should be served as soon as it is cooked.
Pressure cooking is an excellent method to use where speed is required. A specially adapted pan or pressure cooker is used, which is placed on top of the stove. The food to be cooked is placed in the cooker with a measured quantity of liquid, and the lid sealed down. When the liquid has reached boiling point, the valve on top of the lid is closed, and the pressure is built up over a gentle heat.
A loud hiss signals that the correct pressure has been reached, and the cooking is timed from this point. The main advantage of pressure cooking is that it reduces cooking time considerably, so that it is a particularly good method for stews and puddings which normally need several hours. Soups, vegetables and fruit can be cooked in a matter of minutes. Other advantages are that the method is very economical on fuel, and secondly, joints of meat and cakes can be cooked by people without an oven. Disadvantages often quoted are that the food is rendered tasteless, and loses its color. But it must be remembered that as much less fluid is used than usual in a much shorter space of time, the food does not cook for hours in the seasoning and juices, so it is better to season the food well directly before placing it in the pan. Discoloration is almost always as a result of overcooking: in pressure cooking the time is critical and, in the case of green vegetables, even a minute over the recommended time may cause the vegetables to lose their color. However, if these points are borne in mind, pressure cooking can produce good results with a wide range of dishes.
Processes Allied to Cookery
Other forms of cooking include blanching, i.e. putting food into boiling water for a minute, and then plunging it into cold. This helps to remove the skin of tomatoes, peaches or almonds. Another way of blanching is by putting the food into cold water, bringing it to the boil, and plunging it again into cold water: this method is used in the preparation of certain kinds of offal. To caramelize is to heat sugar gently until it turns brown, when it can be used for caramel custard or caramel rice; parboiling is partly or half boiling, the cooking being continued in another way, for instance, potatoes are more easily digested if parboiled before roasting.
Scalding is heating a liquid just below boiling point; milk, for instance, can be treated this way to prevent it becoming sour quickly in hot weather; searing is forming a coating over the surface of meat; sousing is cooking food slowly in vinegar and spices: herrings and mackerel can be cooked this way.