Principle of Food Science and Processing 2024 Lect 9 Cooking Methods PDF

Cooking methods and nutrition 9th lecture Dr. Mohamed Elsaadany  Outlines Definition An introduction Moist cooking methods Boiling Grilling Blanching Frying Simmering Deep-Frying Bra...

Cooking methods and nutrition 9th lecture Dr. Mohamed Elsaadany  Outlines Definition An introduction Moist cooking methods Boiling Grilling Blanching Frying Simmering Deep-Frying Braising Stir-Frying Steaming Sautéing Poaching Pan-Broiling/Frying Stewing Processing and nutrients Dry cooking methods Effects of processing on vitamins Baking Effects of processing and storage on Broiling nutrients Roasting How to minimize nutrients loss Grilling Dr. Mohamed Elsaadany 2  Introduction Definition of cooking Cooking is a means of processing food, without which many foods would be unfit for human consumption Importance of cooking food Prevent many food born illnesses that would otherwise manifest if the raw food was eaten Provides an opportunity to create well-balanced meals Improve food taste, color and flavors and palatability of foods Improve digestibility and absorption of nutrients Cooking produces the desired texture, flavour and palatability in food. Making phytochemicals more available, for instance, phytochemicals are more available in cooked tomatoes than in raw tomatoes. Some substances in soya beans, kidney beans and lentils contain lectins which can produce toxic effects unless cooked prior to eating. Egg whites and some fish, unless cooked, are not an effective source of the vitamins biotin and vitamin B-1 respectively. Heating flour during baking increases the amount of niacin Dr. Mohamed Elsaadany 3  Cooking methods Moist-heat cooking method: Heat is transferred by water, water based liquid, or steam. Dry-heat cooking method: Heat is transferred by air, radiation, fat, or metal. Dr. Mohamed Elsaadany 4 1 Moist Cooking Methods Dr. Mohamed Elsaadany 5  Boiling Boiling is the most intense and destructive moist-heat cooking methods. It results in very large, vigorous bubbles which indicates a temperature of 100C/212°F. it is usually used for hardy ingredients including beans, vegetables with tough texture such as corn and potato It also used to thicken sauce or concentrate flavor of a soup Needs large pan enough for food, the water then boiled then food is added. Results in high nutrient loss and toughens protein Dr. Mohamed Elsaadany 6  Blanch Blanch is done in two steps, boiling food and then quickly plunging it in ice water to stop the cooking effects. is used prior to freezing, drying, or canning vegetables or fruits to inactivate enzymes, modify texture, remove the peel, and wilt tissue is also used to preserve color, flavor, and nutritional value of fruits and vegetables Times and temperatures are based on the type of food, size, shape, and other factors Dr. Mohamed Elsaadany 7  Simmer Definition The process of simmering involves cooking food in hot liquids that are held at a temperature that is slightly above poaching but below the boiling point of water. Generally simmer temperature is between 82° - 99°C Differs from boiling in that the bubbles rise gently and just break the surface Used to cook many food such as fruits, vegetables, and less tender cuts of meat and poultry Use water when possible To simmer, bring water to a boil; add food; when water begins to boil again, reduce the heat so food simmers Some nutrients are lost Dr. Mohamed Elsaadany 8  Poach Poaching is one of the most gentle cooking methods at 160-180 °F (71-82 °C). It is simmering food in small amount of water until cooked Particularly useful for infusing fruits, vegetables and meats (particularly fish) with flavors. Egg also cooked with this method Dr. Mohamed Elsaadany 9  Scald Scalding (from 55° C to 63° C) is very gentle cooking processes, even more gentle than poaching. Liquid brought to the scalded point is heated to where small bubbles may appear to cling to the sides of the pot. is used to help solids, such as sugar, flour, or chocolate, dissolve more easily into the liquid (milk). Scalding is also used in the poultry industry to make feathers easier to remove prior to processing. Dr. Mohamed Elsaadany 10  Steaming Definition Cooking food over, not in, boiling water Food usually in a steamer basket that fits inside pan Boil small amount of water in bottom of pan; place basket in pan; cover to trap steam Water does not touch food Vegetables and fish often cooked this way Foods retain their color, shape, and flavor well Few nutrients are lost Cooking time longer Dr. Mohamed Elsaadany 11  Braise Is a combination of dry and moist cooking. food is first sautéed or seared at a high temperature, then finished in a covered pot at a lower temperature while sitting in some liquid and flavor. Braising of meat is often referred to as pot roasting but can be used for vegetables and other foods. Brasing uses low-medium temp, small amount of liquid for long periods and is usually covered and in a deep vessel Braising is typically used for slow cooking meats, by using a small amount of liquid, but the method can be used for vegetables and other foods. Braising can be done on the stove or in the oven. Dr. Mohamed Elsaadany 12  Stewing Stewing is a combination cooking method that uses small, uniform pieces of meat that are totally immersed in liquid and slowly simmered. In this case, the food and the liquid are served together as one dish. For stewing, first cut the main food item into bite-sized pieces, and either blanch or sear them. As with braising, cook the food in oil first, and then add liquid. Stewing requires more liquid than braising. Cover the food completely while it is simmering. Dr. Mohamed Elsaadany 13  Pressure cooking Pressure cooking is using steam pressure in a tightly sealed pot to cook food. Cooks 3-10 times faster because cooks in temperatures above 212o F Best for foods that take a long time to cook – less tender cuts of beef, poultry, dry beans, soups, one-dish meals, vegetables Dr. Mohamed Elsaadany 14 2 Dry Cooking Methods Dr. Mohamed Elsaadany 15  Dry Heat Methods Definition Dry heat cooking methods are those that to not rely on any added liquid to complete the cooking process. In dry-heat cooking, food is cooked either by direct heat, like on a grill, or by indirect heat in a closed environment, like in an oven. Dr. Mohamed Elsaadany 16  Baking Definition Refers to the cooking in an enclosed space such as oven with dry heat. In conventional ovens (without fan), or in convection ovens( with fan) dry heat is circulated around the baked good and cooked evenly from all sides. but in the later food is cooked quicker and often far more precisely than a conventional oven can. Can range from 200F to 500F (94-260°C) Backing bakeries are common examples To bake, preheat oven 10 minutes before use; place pans in middle of oven for even cooking. Dr. Mohamed Elsaadany 17  Roasting Definition While roasting today is identical to baking in it’s use of a closed oven and method of dry heat, the term is typical used to refer to cooking meats or vegetables uncovered in the oven. Like baking, roasting can caramelize and brown the crust or outside of an ingredient. This cooking method lends it’s name to red meats cooked in this fashion: the roast. Can be between 250F upwards of 450F (120-230 °C) Dr. Mohamed Elsaadany 18  Broiling / Grilling Like baking and roasting, broiling and grilling are two more methods that are very similar to each other Unlike baking or roasting, broiling and grilling use direct heat, often an open flame to cook something hot and fast. While grilling is typically considered to contain a flame on the bottom and broil an element on the top, either can refer to the use of a flame or using a heat source on the top or bottom – usually ranging depending on region. Dr. Mohamed Elsaadany 19  Griddling Griddling is cooking a food item on a hot, flat surface (known as a griddle) or in a relatively dry, heavy-bottomed fry pan or cast-iron skillet. Dr. Mohamed Elsaadany 20  Frying Definition Frying refers to any form of cooking utilizing fat. frying – Deep frying – is a dry cooking method, because it doesn’t rely on water or steam, There are two general categories of Frying: pan frying and deep frying. Pan frying can be narrowed down even further into four specific techniques: pan frying, sautéing, sweating and cooking on a griddle or saute pan Dr. Mohamed Elsaadany 21  Deep Frying Definition Deep Frying is a cooking technique involving the complete submersing of food into hot fat, typically oil. If the temperature of the fat/oil is too low, the food will absorb oil. If it is too high, the product will brown or burn before cooking through. High temperature of up to 400°F (204°C) is maintained to create golden-brown surface textures in a short amount of time. Used for tender foods, vegetables and some breads (doughnuts) Dr. Mohamed Elsaadany 22  Pan Frying Definition Pan Frying, only uses a small amount of fat for lubricating the pan (or no fat for certain products which creates its own fat). Pan frying allows for darker browning but also allows more moister to escape the food, as compared to deep frying. Food may need turning several times during process for even, complete cooking Often used to brown meat before cooking in moist heat Dr. Mohamed Elsaadany 23  Sautéing Definition The sautéing method cooks food rapidly in a small amount of fat on relatively medium to high heat to aid in browning and keeping vegetables crisp Chopped vegetables (onions and peppers), small pieces of meat and fish are normally used where in pan frying larger pieces are used Dr. Mohamed Elsaadany 24  Sweating Sweating is similar to pan frying and sautéing in that a small amount of fat is Instead of a high heat or quick cooking process, sweating uses much lower heat and thus requires more time. sweating pulls moisture from the vegetables being cooked. Sweating is also used when you want to avoid browning an ingredient. Dr. Mohamed Elsaadany 25  Stir frying Definition Is a combination of Frying and moist-heat cooking Small pieces of food quickly fried in small amount of fat; stirred constantly to avoid sticking; small amount of liquid added near end of cooking time; pan covered to allow food to steam briefly Most often used for cooking mixtures of vegetables and other foods Dr. Mohamed Elsaadany 26  Smoking point Definition The smoke point or burning point, is the temperature at which an oil or fat begins to produce a continuous bluish smoke that becomes clearly visible, dependent upon specific and defined conditions Every fat has a smoking point temperature at which smoke and breaks down chemically No longer good for cooking Animal fats – butter, lard – have low smoking points Vegetable fats – safflower, soybean, corn, and peanut oils – relatively high smoking point – best choices for frying Dr. Mohamed Elsaadany 27 3 Effects on nutrition Dr. Mohamed Elsaadany 28  Introduction In general, the content of minerals in a food is not significantly reduced by most cooking methods, although they may leech in small quantity into cooking fluids. Fat content can be reduced when cooking temperatures cause it to become liquid and flow out of foods. Carbohydrates may be leeched into cooking fluids or begin to breakdown at higher temperatures. Complex proteins will denature with heat and long cooking times. Generally, water soluble vitamins (B-group, and C) will leach into cooking water and are less heat stable than their fat-soluble counterparts (vitamins A, D, E, K). Degradation by air or light is generally a very slow process and should not be a concern when preparing foods for cooking but is more of a problem during storage. The longer you cook a food the more you will degrade the nutrients in it. Calorie content of food is not altered by cooking, unless you are draining liquid fats or skimming solid fats during cooking. Proteins will be degraded by extremes of pH and temperature Dr. Mohamed Elsaadany 29  Introduction Non-enzymatic browning (Maillard reaction) Non-enzymatic browning is accounts for the development of flavour, colour and aroma. This non-enzymatic browning process is called ‘Maillard Reaction’. It is a chemical reaction that occurs between amino acids and reducing sugars when exposed to heat, affecting the bioavailability of some amino acids such as lysine. The protein of connective tissue, collagen, is not denatured on heating but moist cooking methods softens and starts to convert collagen to gelatine. Dr. Mohamed Elsaadany 30  Effects of processing on vitamins Water-soluble vitamins (B-group and C) are more unstable than fat-soluble vitamins (K, A, D and E) during food processing and storage. The most unstable vitamins include: folate thiamine vitamin C. More stable vitamins include: niacin (vitamin B3) pantothenic acid (vitamin B5). biotin (vitamin B7) vitamin K vitamin D Dr. Mohamed Elsaadany 31  Effects of processing Use of fertilizers The use of fertilizers containing nitrogen can result in a small increase in protein content of some foods. But the amount of vitamin C is usually decreased, probably because of the increased growth of the fruit or vegetable. There is no nutritional difference between plants that have been organically fertilized and those fertilized using conventional fertilizers. Milling During the milling of cereals, part of the original grain is removed. Depending on the extent of the milling process there are large losses of fat, dietary fiber, vitamins B-l, B-2 and niacin, and elements (minerals). Foods made from whole meal flour are better sources of these nutrients than those prepared from white flour. Dr. Mohamed Elsaadany 32  Effects of processing Controlled atmosphere (CA) storage and ripening, and waxing Brief storage of fruits and vegetables, under ripening gas is used in some fruits, most notably tomatoes and bananas. No significantly different in nutrient composition compared with fruit that has matured normally, although it may taste differently. Some fruits and vegetables are artificially waxed to make them shiny and attractive and promote their sale. The wax coating for a short time slows the loss of moisture, which causes weight loss and wilting. No significant differences between waxed and unwaxed food Dr. Mohamed Elsaadany 33  Effects of processing Cutting, trimming and peeling Trimming, peeling and cutting, used to remove inedible or undesirable portions from food, will obviously lead to nutrient loss. There is often a higher concentration of some nutrients in the outer portions of fruits and vegetables. Peeling fruits and vegetables such as apples, peaches, pears, potatoes and carrots, lead to a disproportionate loss of many vitamins. It is wise to discard the outer parts only if they are inedible, limp or too difficult to clean. Trimming the fat from meat can be beneficial in reducing energy intake as well as decreasing the amount of saturated fat in the diet. Dr. Mohamed Elsaadany 34  Effects of processing Blanching Blanching is the heating of fruit or vegetables for a short time with either steam or water, and is an essential step before canning, drying or freezing of food. Varying amounts of nutrients are lost in this process, in particular the water- soluble vitamins B1, B2, C, niacin and folacin. Dr. Mohamed Elsaadany 35  Effects of processing Cooking Losses of protein and carbohydrate during cooking are generally small. The amount of fat in food may be either reduced or increased depending on the method of cooking. Generally, grilling will lower the fat content and frying will increase it. The smaller the size of the pieces being fried, the greater the amount of fat that will be absorbed per 100 grams. The largest vitamin loss during cooking is usually due to destruction of vitamin C, and to a lesser extent vitamin B1 and the other water-soluble vitamins. Pressure cooking Generally, pressure cooking will retain more nutrients than normal boiling. However, food steamed or boiled in a small amount of water in a tightly covered saucepan is likely to be as nutritious as food cooked in a pressure cooker. Dr. Mohamed Elsaadany 36  Effects of processing Microwave ovens Microwave cooking is much quicker than conventional cooking. The microwaves preferentially heat the water in food so that the cooking process is essentially similar to that of steam cooking. 20–30% of the vitamin C and B1 in green vegetables is lost during microwaving this is similar to that achieved by cooking with steam or using a small amount of water in a tightly covered saucepan Freezing The major nutrient losses that occur in frozen foods are not due to freezing as such but due to the blanching that occurs before freezing, and then during subsequent thawing and cooking. Dr. Mohamed Elsaadany 37  Effects of processing Dehydration With the exceptions of vitamin C and provitamin A, the nutrient losses that occur in drying are not large. If the food is left in water to rehydrate, or is boiled, then there will be the additional normal cooking losses. If the food is eaten in the dried form, such as dried apricots, then the food is a concentrated source of many nutrients, including dietary fiber Canning Nutrient losses occur from destruction during heating and storage stages. Some nutrients, such as water-soluble vitamins and minerals, may dissolve in the water in the can, but they are lost only if this liquid is not consumed. Dr. Mohamed Elsaadany 38  Effects of processing Pasteurization Nutrient losses during pasteurization of milk and fruit juices are generally small. in the case of fruit juices they must contain not less than a specified minimum amount of vitamin C. This generally means that vitamin C is added by the processor To minimize further nutrient losses, milk and fruit juices should be stored away from light and in a cool place. Dr. Mohamed Elsaadany 39  Composition of Eggs Toasting A loss of about 10 to 30 % of the vitamin B1 present in bread occurs on toasting. Sprouting Sprouted seeds require much shorter cooking time than the dry seeds. In addition, there is an increase in the vitamin C content and also in some B-group vitamins. Dr. Mohamed Elsaadany 40  HOW TO MINIMIZE NUTRIENT LOSS Choose fresh foods that are not over-ripe, bruised, cut or scraped. Store foods in a cool, dark place. Unless the peel or outer layer is unpalatable, damaged or contaminated, cook the food whole. If it is necessary to slice the raw food. then try to keep the pieces as large as possible. When boiling, add the raw food to the boiling water rather than to cold water. Use steam or the smallest amount of water possible; it is not necessary to cover the food. If possible use the cooking water for gravies, sauces or soups as it is a source of water- soluble vitamins and elements (minerals). Cook for the minimum time necessary to make the food palatable and safe. Once cooked, eat as soon as possible. Do not keep the food warm for long periods. Do not use baking soda to help keep the green colour of vegetables, as this increases loss of vitamin C. and B1 Do not use copper utensils. (Copper helps to destroy vitamin C.) Dr. Mohamed Elsaadany 41 THANKS! Any questions? Dr. Mohamed Elsaadany 43