case 13



Variations in the technique of food preparation are often more difficult to control than variations in the type and amount of food used. Air, water, and heat are important factors in food preparation, but they are not independent of each other, and they may affect more than one quality of a food. Mixing of the ingredients and cooking are two phases of food preparation in which these factors contribute to the quality of the finished product. The food service sergeant must insure that personnel responsible for preparing and serving meals are aware of the influences that air, water, heat, the method of mixing, and the method of cooking have on the palatability and acceptability of food items. Some of these influences and some techniques for controlling them are discussed in this section.


The four methods of mixing are stirring, beating, folding, and blending. Each recipe specifies the mixing method to be used to obtain the best results; if one method is substituted for another, the results may not be satisfactory. When the mixing techniques are controlled by use of an electric mixer, the effects of individual differences such as pattern or force of strokes are decreased. The standard recipe indicates the speed and length of time the electric mixer should be used to obtain the desired result. Air is purposely whipped into some foods like egg white, whipped cream, and other foams. Some foods change flavor and others become undesirable when they are aerated. The nutritive values of fruit juices may be decreased if juices are aerated and held for a long time before being served. The food service sergeant must insure that the dining facility personnel thoroughly understand and use the proper method of mixing so that the quality of the food served meets the standard.


Stirring is passing a spoon or other implement through a substance, with a continuous circular movement for the purpose of mixing, blending, dissolving, or cooling. The main purpose of stirring is to mix ingredients.


Beating is bringing the bottom mass constantly to the top, trapping as much air as possible into the mixture. Dining facility personnel must be made aware of the importance of beating a mixture for the time called for in the recipe to obtain best results.

FOLDING. Folding is blending thoroughly without losing any of the air previously worked into the material by beating. A large utensil must be used, and only a small amount of the ingredient to be folded into beaten mass is added at a time. Folding should be done by hand to obtain the desired result, but standard recipes for food items like sponge and angel food cakes allow for use of electric mixers.

BLENDING. Blending is mixing thoroughly two or more ingredients.


To cook is to subject foods to the action of heat to make them more digestible. Meats are cooked by either dry or moist heat methods, depending on the cut of meat. Vegetables are generally cooked by one of three methods: baking, steaming, or cooking in water. Baking is the primary method for cooking breads, quickbreads, cookies, pies, cakes, and other pastries.


Methods of cooking meat in which air surrounds the meat and evaporation is permitted are termed dry-heat methods. Dry heat is used in roasting or baking, broiling, pan-broiling, sautéing, deep-fat frying, and grilling the more tender cuts of meat. Meats cooked by dry-heat methods usually come in contact with a hot surface, such as the frying pan during the browning or actual cooking process or the baking utensil when meat is dry-heat cooked in the oven. If the following procedures are used for cooking meat by a dry-heat method other than deep-fat frying, quality products should result:

  1. Do not allow the transfer of heat through the pan at too rapid a rate, or the meat may burn on the bottom before the top is browned sufficiently.
  2. When cooking a roast by the dry-heat method, it should be placed on a rack, fat side up then into a pan with low sides and roasted at a constant oven temperature of 325° F.
  3. Do not overheat meat because overheating causes protein in the meat to toughen and become less digestible.
  4. When cooking a roast by a dry-heat method, do not cover the roast.
  5. Turn boneless roasts frequently to prevent dryness. Never stick a fork in a roast, or the juices will cook out.
  6. Often baste roasting fowl with the drippings to prevent dryness.
  7. When pan-broiling meat, do not allow fat to accumulate in the pan, or the meat will fry and become a less desirable product.
  8. When broiling meats, do not salt them, because sit tends to draw out the meat extractives. Salt also retards the browning process, which may result in excessive cooking to produce the desired color.


Moist-heat cooking is the method of cooking meet in liquid or steam. Simmering, braising, stewing, and steaming are the moist-heat methods. Moist heat is required to make tender those meat cuts which contain large amounts of connective tissue. The containers used for cooking meats by the moist-heat method are usually covered to reduce the cooking time and to preserve the flavor of the meat. If the following procedures are used for cooking meat by the moist-heat method, quality products should result:

  1. When browning meats by the braising method, use moderate to high heat to develop the brown color and roasted flavor as rapidly as possible so as to prevent excessive shrinkage.
  2. When cooking meats in water or other liquid, cover the meat with the liquid so the meat will cook evenly.
  3. Season the meat during the cooking process to allow the seasoning to cook into the meat and enhance the flavor of the meat and the stock.


Deep-fat frying is a dry-heat method of cooking in hot shortening heated to 350° to 365°F., depending upon the type of food. A thermometer should be used to control the temperature, because the shortening heated to the smoking point or beyond develops acrolein, which has an acrid flavor and an irritating odor. Once shortening is overheated, it should not be used. Breaded items such as meat croquettes, poultry, fish, onions, eggplant, cauliflower, and parsnips may be cooked by deep fat frying. Parsnips should be steamed or boiled until tender before they are breaded. Potatoes, corn fritters, and doughnuts may also be cooked by this method, but they do not require breading. If the following procedures are used, as applicable, for deep-fat frying, quality products should result:

  1. Inspect shortening to determine if it is clean and suitable for use.
  2. Bread the items so that their surfaces will not burn. Thoroughly coat the items with any of the various breadings such as flour, corn meal, or bread crumbs so they will brown evenly.
  3. Shake the items before they are put into the fry basket so that excess breading will not shake off and settle to the bottom of the shortening and burn.
  4. Use pieces that are as uniform as possible.
  5. Do not overfill the fry basket or the temperature of the shortening will be reduced, the cooking time will be increased, and the resulting product will be greasy and unappetizing.
  6. Do not overbrown the items, or they will become dry and tasteless.
  7. Food items should be allowed to drain to retain their crispness and at the same time allow for better digestion.
  8. Too many items should not be fried at one time, because the temperature of the fat will be reduced so low that the pieces will cook evenly and will absorb excess fat.


Steaming is cooking in a steam media with or without pressure. When the steaming method is used, there is little loss in minerals and vitamins, and the vegetables retain their original shape. The exact cooking time varies, depending on the variety and maturity of the vegetable and the size of the pieces.


Boiling is the most commonly used method of cooking vegetables. All vegetables, except the strong flavored vegetables such as broccoli, brussels sprouts, cabbage, cauliflower, kohlrabi, and onions should be cooked in just enough water to keep the cooking utensil from boiling dry.

The preparation schedule should indicate cooking time for progressive cookery as a control of quality, color, and eye-appeal of these items. The following suggestions should aid personnel in obtaining a quality product:

  1. Heat the water to boiling, and salt it before adding vegetables.
  2. Bring the water back to a boil as quickly as possible.
  3. Simmer until just tender.
  4. Drain and serve at once.


Baking is done using dry heat in an oven; little or no water is used. Baking of meat is usually called roasting. Baking is considered the best cooking method for preserving the flavor and nutrients of vegetables. Breads, quickbreads, cookies, pies, cakes, and other pastries are baked. Baking time depends upon the size of the item, the temperature of the oven, the type of item, and the particular ingredients used. Listed below are a few techniques for controlling the quality of all types of baked products.

MEATS. See DRY HEAT above.

VEGETABLES. White potatoes, sweet potatoes, onions, and tomatoes are particularly adaptable to baking. Vegetables that can be baked in their skins will have better flavor and will be more nutritious; however, if the vegetables are properly pared, they will lose only a small amount of nutrients. Pared vegetables and sliced raw vegetables may be baked in a casserole. To control the quality of baked vegetables, the cook must be careful not to overbake or scorch the items.

CAKES AND OTHER ITEMS. The baking of cakes, breads, and other like items involves a complicated series of chemical and physical reactions. Because each ingredient and each step of the preparation contributes at least one characteristic to the finished product, it is important that the baking instructions given with the recipe be followed very closely to prevent failures. Listed below are other suggestions that should help in controlling the quality of baked foods.



The effects of oxygen, one of the principal elements of air, are often overlooked in food preparation. Oxygen is a very reactive gas that forms chemical unions with many substances, a process called oxidation. The oxidized food products may be undesirable from a nutritional or a palatability standpoint-often both. Listed below are some current ideas on the effects of air on the quality of food items with some suggestions for controlling these effects.

  1. Because ascorbic acid is particularly susceptible to oxidation, care should be taken to prevent unnecessary exposure of broccoli and other ascorbic-acid-rich foods to air.
  2. The rate of oxidation of foods is greater at room temperature than at refrigerator temperatures. Therefore, refrigeration or freezing temperatures should be used for storing most foods containing ascorbic acid.
  3. Ascorbic acid in the presence of other acids is less susceptible to oxidation changes than when alone. Citrus fruits, strawberries, and tomatoes contain other acids and resist oxidation of ascorbic acid to a greater extent than do cabbage, greens, broccoli, and cauliflower.
  4. A covering of sugar or syrup over prepared fruits, tight covers on juice containers, and other similar practices reduce oxidation by limiting the amount of oxygen coming in contact with the food.
  5. The ascorbic acid-citric acid combination in lemons, oranges, and other citrus fruits can be used as an antioxidant to prevent the browning of sliced bananas, apples, peaches, and other light-colored fruits.
  6. Copper sieves or other metallic utensils containing traces of copper should not be used for straining fruit juices or for pureing fruits and vegetables which contain ascorbic acid, because copper increase the rate of oxidation.
  7. Oxidation decreases the nutritive value of vitamin A.
  8. Fats are also changed by oxidation. Oxidized fat develops an unpleasant odor and becomes rancid.



The temperature at which food is cooked is one of the most important factors in the quality control of the food. Using the temperature listed in the standard recipe is the best assurance of quality control. The heat must penetrate to the center of the food if the entire item or pan of an item is to be cooked. The shorter the distance to the center, the more quickly the food will cook or cool. Therefore, the food service sergeant must insure that close attention is paid to the temperature used to cook foods. Listed below are some current views on the reaction of foods to excessive heat.


Cooking meat slowly at temperatures ranging from 300° to 350° F. yields the greatest number of servings and improves the appearance and nutritive value of the finished food. Tests have shown that cooking losses due to shrinkage are only about 10 to 15 percent when meat is cooked t an oven temperature of 250° to 325° F. Figure 10 shows the results of cooking one roast at 500° and another at 325° F.


Fats and oils, due to their refining methods, do have different smoking points and should be used accordingly. It is recommended that most deep fat frying be done at 350° F to 365° F.


Excessive heating impairs the nutritive value of protein, and most often overly heated protein is not readily digestible. Some results of changes in proteins are:

  1. Poultry baked at high temperatures becomes stringy, tough, and unappetizing.
  2. Eggs must be cooked at low temperatures. Improperly cooked egg of any type will be rubbery and tough and will be less appetizing and less digestible than eggs cooked at the proper temperatures.
  3. When excessive heat is used for scrambling eggs, the liquid is expressed, resulting in a watery finished product.
  4. If eggs are boiled at high heat, the yolks will turn dark (fig. 11).
  5. If souffles are cooked at too high a temperature, they will droop.
  6. If custards are cooked at too high a temperature, they will curdle and weep.


Vitamin losses occur as follows:

  1. The fat-soluble vitamins (A, D, E, and K) are relatively stable when heated in the absence of air, but losses occur when these vitamins are heated in the presence of oxygen. Prolonged heating at high temperature in the presence of air can be expected to destroy completely these nutrients. Quality changes in the food items resulting from vitamin losses can be detected by our senses.
  2. Vitamin B1 is very sensitive to heat; if food containing it is heated in the presence of air and light, large losses in this nutrient result.



Water is another important factor in quality control of food preparation. It surpasses all other cooking liquids in its capacity to change the physical and chemical structure of plant materials and animal tissues used for food. Many foods are washed with water, cooked with water, or moistened with water. Colors, flavors, acids, sugar, some proteins, minerals, and certain vitamins (B-complex vitamins and ascorbic acid) may be dissolved into the water that comes in contact with cut or bruised surfaces. When skins are pared away, some of the cells are ruptured, and cellular materials may be dissolved if the food is washed or covered with water. Therefore, foods to be washed should be left whole whenever possible in order to retain their water soluble substances. Procedures for cooking must be chosen according to whether the water added for the cooking process is to be used or discarded.


The composition of water has considerable effects on foods cooked in water. The hardness of water is due to various combinations of salts. Some of the effects of hard and soft water on the quality of the cooked product are:


. Some suggestions for use of water in cooking vegetables are:

  1. Use the minimum amount of water necessary to preserve flavor and food value.
  2. Start with boiling salted water.
  3. Do not let vegetables soak before cooking, except for some dried legumes.
  4. Do not stir air into the water while food is cooking.
  5. Do not let vegetables stand in hot water after cooking. The vegetables will continue to cook, become extremely soft, and lose their natural color.


Water or other liquids are used in moist heat cooking of meats. When water is used, the following suggestions should be observed to control the quality of the finished meat dish:

  1. Only a very small amount of liquid is used for braising meat that has been browned. If additional water is needed to prevent the meat from cooking dry and scorching, it should be added in very small portions.
  2. For stewing meat, a little more water is needed than for braising meat.
  3. For simmering soup stock and large, unbrowned pieces of meat, the amount of water should be just enough to cover the meat. If an excess is used, the flavor of both the meat and the broth will be diluted.