Part One: Physical & Chemical Process in Cooking Course Objectives After completion of Part One “Physical & Chemical Process in Cooking” you should: Understand why foods are cooked, and the effects of the cooking process on foods Know the preparations of foods needed before cooking Understand how heat is transferred to foods through conduction, convection and radiation Understand how heat affects foods Know the effects of Water in cooking Know the effects of Carbohydrates in cooking Know the effects of Fat in cooking Know the effects of Protein in cooking Know the Physical and Chemical Preservation Methods Know the rules and guidelines of refrigerating, freezing and thawing foods Know the advantages & rules in using convenience foods
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Part One: Physical & Chemical Process in Cooking Course Contents Introduction The cooking process & its effect on foods Preparation of foods before cooking
Heat Transfer Conduction Convection Radiation
Effects of Heat
Protein Starches Sugars Water Fats
Effects of Water in Cooking
Water can Expand Water Conducts Heat Water Cleans & Sanitizes Water is Anomalous
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Effects of Carbohydrates in Cooking
Carbohydrates are partially Water Soluble Carbohydrates have Sweetening Properties Carbohydrates Attract Water Carbohydrates can Thicken Carbohydrates can Brown Carbohydrates can Ferment
Effects of Fat in Cooking
Fat Dissolves certain Substances Fat Improves Taste Fat is lighter than Water Fat has a High Smoking Point Fat Conducts Heat evenly Fat Separates Substances Fat has a High Melting Point Fat Inhibits Egg Whites from Foaming Fat can be Emulsified Fat Spoils Easily
Effects of Protein in Cooking
Proteins are Soluble Proteins Foam Disadvantage of Protein Coagulation Proteins Brown at High Temperature Proteins Spoil Rapidly
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Preservation Methods
Physical Process of Preservation Chemical Process of Preservation Rules for Refrigeration Rules for Freezing Preparation of Foods before Freezing Thawing of Frozen Foods Preparation of Frozen Foods
Convenience Foods What are Convenience Foods Rules for Working with Convenience Foods
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Introduction Principles of Cooking Some foods can be eaten raw and unprepared, but most must be cooked. Cooking can be defined as the transfer of energy from a heat source to a food. This energy alters the food's molecular structure, changing its texture, flavor, aroma and appearance. But why is food cooked at all? The obvious answer is that cooking makes food taste better. Cooking also destroys undesirable microorganisms and makes foods easier to ingest and digest.
To cook foods successfully: 1) You must understand the three ways in which heat is transferred: A. Conduction B. Convection C. Radiation 2) You should understand what the application of heat does in foods to: Proteins Sugars Starches Water Fats 3) You must understand the cooking methods used to transfer heat: broiling, grilling, roasting, butter roasting and baking, glazing, gratinating, sautéing, stir-frying, pan-frying, deep-frying, poaching, simmering, boiling, blanching, steaming, braising and stewing. Each method is used for many types of food, so you will be applying one or more of them every time you cook. The cooking method you select gives the finished product a specific texture, appearance, aroma and flavor. A thorough understanding of the basic procedures involved in each cooking method helps you produce consistent, high-quality products.
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The cooking process:
Causes fiber to soften Destroy microorganisms Create flavor and aromas Facilitates chewing and increases digestion Changes textures, taste, and color and thereby increases number of dishes to create.
Before consuming and even before cooking, most foods must be prepared: Fruits and vegetables should be washed thoroughly to remove dust, dirt, disease-causing microorganism, and possibly pesticide residues. Fruit and vegetables are trimmed; for example, peels, stems, leaves and seeds are removed. Fish is scaled and filleted Meat is trimmed, de-boned if needed, and portioned. Dried foods are reconstituted in water to allow the starch and protein to expand. Large foods are cut into smaller pieces to speed up cooking and digestibility. It is essential to understand the chemical and physical processes that affect food preparation, to produce foods of consistent quality with a minimum loss of taste or nutrients.
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Physical and Chemical Process in Cooking Heat Transfer Heat is a type of energy. When a substance gets hot, its molecules have absorbed energy, which causes the molecules to vibrate rapidly, expand and bounce off one another. As the molecules move, they collide with nearby molecules, causing a transfer of heat energy. The faster the molecules within a substance move; the higher its temperature. This is true whether the substance is air, water, an aluminum pot or a sirloin steak. Heat energy may be transferred to foods via: A. Conduction B. Convection C. Radiation Heat then travels through foods by conduction. Only heat is transferredcold is simply the absence of heat, so cold cannot be transferred from one substance to another.
A. Conduction Conduction is the most straightforward means of heat transfer. It is simply the movement of heat from one item to another through direct contact. For example, when the flame of a gas burner touches the bottom of a sauté pan, heat is conducted to the pan. The metal of the pan then conducts heat to the surface of the food lying in that pan. Conduction is a relatively slow method of heat transfer because there must be physical contact to transfer energy from one molecule to adjacent molecules. Consider what happens when a metal spoon is placed in a pot of simmering soup. At first the spoon handle remains cool. Gradually, however, heat travels up the handle, making it warmer and warmer, until it becomes too hot to touch. Some materials conduct heat better than others. Water is a better conductor of heat than air. This explains why a potato cooks much faster in boiling water than in an oven, and why you cannot place your hand in boiling water at a temperature of 100°C, but can place your hand, at least very briefly, into a 200°C oven. Generally, metals are good conductors, while liquids and gases are poor conductors.
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Conduction is important in all cooking methods because it is responsible for the movement of heat from the surface of a food to its interior. As the molecules near the food's exterior gather energy, they move more and more rapidly. As they move, they conduct heat to the molecules nearby, thus transferring heat through the food (from the exterior of the item to the interior). In conventional heating methods (non-microwave), the heat source causes food molecules to react largely from the surface inward so that layers of molecules heat in succession. This produces a range of temperatures within the food, which means that the outside can brown and form a crust long before the interior is noticeably warmer. That is why a steak can be fully cooked on the outside but still rare on the inside.
B. Convection Convection refers to the transfer of heat through a fluid, which may be liquid or gas. Convection is actually a combination of conduction and a mixing in which molecules in a fluid (whether air, water or fat) move from a warmer area to a cooler one. There are two types of convection: 1. Natural 2. Mechanical 1. Natural convection occurs because of the tendency of warm liquids and gases to rise while cooler ones fall. This causes a constant natural circulation of heat. For example, when a pot of stock is placed over a gas burner, the molecules at the bottom of the pot are warmed. These molecules rise while cooler, heavier molecules sink. Upon reaching the pot's bottom, the cooler molecules are warmed and begin to rise. This ongoing cycle creates currents within the stock, and these currents distribute the heat throughout the stock. 2. Mechanical convection relies on fans or stirring to circulate heat more quickly and evenly. This explains why foods heat faster and more evenly when stirred. Convection ovens are equipped with fans to increase the circulation of air currents, thus speeding up the cooking process. But even conventional ovens (that is, not convection ovens) rely on the natural circulation patterns of heated air to transfer heat energy to items being baked or roasted.
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C. Radiation Unlike conduction and convection, radiation does not require physical contact between the heat source and the food being cooked. Instead, energy is transferred by waves of heat or light striking the food. Two kinds of radiant heat are used in the kitchen: 1. Infrared 2. Microwave 1. Infrared cooking uses an electric or ceramic element heated to such a high temperature that it gives off waves of radiant heat that cook the food. Radiant heat waves travel at the speed of light in any direction (unlike convection heat, which only rises) until they are absorbed by a food. Infrared cooking is commonly used with toasters and broilers. The glowing coals of a fire are another example of radiant heat. 2. Microwave cooking relies on radiation generated by a special oven to penetrate the food, where it agitates water molecules, creating friction and heat. This energy then spreads throughout the food by conduction (and by convection in liquids). Microwave cooking is much faster than other methods because energy penetrates the food up to a depth of several centimeters, setting all water molecules in motion at the same time. Heat is generated quickly and uniformly throughout the food. Microwave cooking does not brown foods, however, and often gives meats a dry, mushy texture, making microwave ovens an unacceptable replacement for traditional ovens. Because microwave radiation affects only water molecules, a completely waterless material (such as a plate) will not get hot. Any warmth felt in a plate used when microwaving food usually results from heat being conducted from the food to the plate. Microwave cooking requires the use of certain types of utensils, usually heat-resistant glass or microwavable plastic. But even heat-resistant glass can shatter and is not recommended for professional use. The aluminum and stainless steel utensils most common in professional kitchens cannot be used because metal deflects microwaves, and this can damage the oven.
Arrows indicate heat patterns during conduction, convection and radiation
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Effects of Heat Foods are composed of proteins, carbohydrates (starches and sugars), water and fats, plus small amounts of minerals and vitamins. Changes in the shape, texture, color and flavor of foods may occur when heat is applied to each of these nutrients. By understanding these changes and learning to control them, you will be able to prepare foods with the characteristics desired. Although volumes are written on these subjects, it is sufficient for you to know the following processes as you begin your study of cooking.
Proteins Coagulate The proper term for the cooking of proteins is coagulation. Proteins are large, complex molecules found in every living cell, plant as well as animal. Coagulation refers to the irreversible transformation of proteins from a liquid or semi-liquid state to a solid state. As proteins cook, they lose moisture, shrink and become firm. Common examples of coagulation are the firming of meat fibers during cooking, egg whites changing from a clear liquid to a white solid when heated and the setting of the structure of wheat proteins (known as gluten) in bread during baking. Most proteins complete coagulation at 71째C to 85째C.
Starches Gelatinize Gelatinization is the proper term for the cooking of starches. Starches are complex carbohydrates present in plants and grains such as potatoes, wheat, rice and corn. When a mixture of starch and liquid is heated, remarkable changes occur. The starch granules absorb water, causing them to swell, soften and clarify slightly. The liquid visibly thickens because of the water being absorbed into the starch granules and the granules themselves swelling to occupy more space. Gelatinization occurs gradually over a range of temperatures from 66째C to 100째C depending on the type of starch used. Starch gelatinization affects not only sauces or liquids to which starches are added for the express purpose of thickening, but also any mixture of starch and liquid that is heated. For example, the flour (a starch) in cake batter gelatinizes by absorbing the water from eggs, milk or other ingredients as the batter bakes. This causes part of the firming and drying associated with baked goods.
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Sugars Caramelize The process of cooking sugars is properly known as caramelization. Sugars are simple carbohydrates used by all plants and animals to store energy. As sugars cook, they gradually turn brown and change flavor. Caramelized sugar is used in many sauces, candies and desserts. But caramelized sugar is also partly, responsible for the flavor and color of bread crusts and the browning of meats and vegetables. In fact, the process of caramelization is responsible for most flavors we associate with cooking. Sucrose (common table sugar) begins to brown at about 170°C. The naturally occurring sugars in other foods, such as maltose, lactose and fructose, also caramelize, but at varying temperatures. Because high temperatures are required for browning (that is, caramelizing), most foods will brown only on the outside and only through the application of dry heat. Because water cannot be heated above 100°C, foods cooked with moist-heat methods do not get hot enough to caramelize. Foods cooked with dry-heat methods, including those using fats, will reach the high temperatures at which browning occurs.
Water Evaporates All foods contain some water. Some foods, especially eggs, milk and leafy vegetables, are almost entirely water: Even as much as 75 percent of raw meat is water. As the internal temperature of a food increases, water molecules move faster and faster until the water turns to a gas (steam) and vaporizes. This evaporation of water is responsible for the drying of foods during cooking.
Fats Melt Fat is an energy source for the plant or animal in which it is stored. Fats are smooth, greasy substances that do not dissolve in water. Their texture varies from very firm to liquid. Oils are simply fats that remain liquid at room temperature. Fats melt when heated; that is, they gradually soften, then liquefy. Fats will not evaporate. Most fats can be heated to very high temperatures without burning, so they can be used as a cooking medium to brown foods.
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Effects of Water in Cooking Water can Dissolve and Infuse Each water molecule consists of two atoms of hydrogen and one atom of oxygen (H²O). The atoms are aligned to form a positive and negative opposite poles. Therefore, water molecules are called bipolar. This makes it possible for the hydrogen to interact with many substances, to either combine or dissolve. Solubility is uncombined with heat, a property used extensively in the kitchen when working with salt, sugar, instant products, and certain proteins. Infusion of color, flavors and aromatics can occur only in hot water. Meat and fish bones, meats, spices, vegetables are infused into various stocks, soups and sauces. Coffee and tea are also infusions.
Water Can Expand Proteins and starches swell when they attract and absorb water. They expand and become less dense, which shortens and eases the cooking process. This is happening in the kitchen: When legume, grains, dried fruits, mushrooms, or vegetables are soaked. When water is incorporated into dough and batters.
Water Conducts Heat The heat conductivity of water is used in the kitchen when hot water or steam is used in the cooking process (blanching, poaching, simmering, stewing, braising, glazing, and steaming). As a rule, the higher the temperature the shorter the cooking time. Heating water sets the molecules in rapid motion until they evaporate as steam at high temperature. Water boils at normal pressure at 100ºC. Increased air pressure (for example in a steamer) resulting in a higher boiling point (adding 0.5 bar increased the temperature to 111ºC; adding 1 bar pressure to 120ºC. If the air pressure is lowered, as in a pressure cooker (where some of the air is removed) or in high altitude, water will boil below 100ºC (with 0.5 bar less air pressure, water boils ate 81ºC; at 500 to 600 meters above sea level, water will boil at 96ºC.
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Water Cleans and Sanitizes Water is used to clean and wash away dirt. Steam can be used to sanitize.
Water is Anomalous Water changes in ways unlike other substances when exposed to temperature changes, which is called anomalous nature of water. Water expanse when it freezes, whereas other substances contract. In a mixture of ice and water, the surface temperature will be 0ºC; below the surface, it will be 4ºC. All other liquids will be cooler below, with surface temperature higher. Ice floats on top of water, while all other frozen substances will sink. Consequently, plants and fish can survive frozen water: the ice surface protects the lower levels from getting too cold. Consequences of Anomalous Properties of Water At 4ºC, water is most dense, and 1 liter water weighs exactly 1000g; at 20ºC only 998 g; and at 0ºC 999gs. At the moment water freezes at 0ºC, the volume increases and one liter ice weighs 917g. The addition of salt, sugar and alcohol will lower the freezing point of water. Some foods, because of the high mineral content will not freeze at 0ºC, but freeze at lower temperature. An ice soufflé with a high sugar and alcohol content may not freeze properly. Freezers should operate below -18ºC. When water freezes, it expands very little but with enormous pressure. That is why full bottles put in the freezer will explode and break.
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Effects of Carbohydrates in Cooking Carbohydrates are Partially Water Soluble Simple sugar and disaccharides, as well as dextrose and glycogen (animal starch) are water-soluble. Warm water dissolves more sugar than cold water. Highly concentrated hot sugar solutions tend to crystallize when chilled. The creation of sugar solutions can be hastened by: Pulverizing: Confectioner’s sugar, as in preparation of cold fruit sauces and desserts. Heating: Hot sugar syrup, as in the preparation of Italian meringue. Agitation: Stirring sugar into tea, coffee, sauces and creams. Water-soluble dextrin will give gloss, clean look, to hot baked goods if they are brushed immediately with water.
Carbohydrates Have Various Sweetening Properties Simple sugars and disaccharides taste sweet but have different sweetening power. The sweetening strength of cane and beet sugar (sucrose) is measured at 100, and then fructose would be measured at 120, invert sugar at 80, malt sugar at 65, glucose at 50 and lactose at 35.
Carbohydrates Attract Moisture Simple sugars (glucose, fructose) strongly attract moisture. To keep baking goods soft and moist, honey is added, because it contains the most simple sugar of all the sweeteners. Confectioner’s sugar is also very moisture absorbent. The ability to absorb large amounts of moisture makes sugar an excellent preservative (jams, jellies, candies, fruits) because spoiling agents, such as yeast and microbes, are deprived of moisture and cannot grow.
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Carbohydrates Can Thicken The ability to thicken is especially high in starches and edible fibers hemicelluloses and pectin. Pectin expanse when boiled with acid and sugar, and it gels (thickens) when cooled. This property is used in the preparation of jams and jellies. Starch (flour, arrowroot, corn, potato) is not water-soluble and will sink to the bottom in a liquid solution. Therefore, it is imperative that all cold starch solutions be stirred just before they are added to thicken stocks and sauces. Starch will start to swell in warm water at about 40ºC. Above 60ºC starch granules, ruptures and binds liquid (soup, sauces and creams). Thickening is usually completed at 80ºC. Different starches thicken at different temperatures. When chilled, the starch mixture achieves a pudding-like firmness. Chilled starch mixtures have forced additional bond, which would tear when beaten, releases water and causing the mixture to become thin and runny. Chilled crèmes should never be whipped in a mixer to smooth them; they should be passed through a fine sieve instead. When starch-thickened foods are cooked beyond 95ºC, the starch bond weakens. That’s why soup and sauces are thinned by letting them cook for a period of time. Long storage of starch-thickened dishes will cause water to be released from the gel. This process is called weeping. Release of moister from starch in bread and baked goods causes them to dry out and become stale, which causes a bad taste. The inclusion of starch in thick white sauces or vanilla crème can prevent egg yolk from curdling, even if the product boils. However, in thin sauce or crèmes, egg yolk will curdle at 80ºC. Liquids thickened with flour should cook slowly for at least fifteen minutes at about 95ºC or above, to ensure smooth, creamy product and complete gelatinization.
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Carbohydrates Can Brown Heating carbohydrates causes them to develop aroma, flavor and color. Sugar heated to 150ยบC will melt into a transparent liquid, which soon turns to a caramel color when heated further. The darker the color the less sweet it becomes. If starch is heated without water to 150ยบC or above, dextrin forms. Dextrin has a light sweet taste and is more desirable than starch. Dextrin develop in the crusts of breads and pastries and in brown roux. Darker browning reduces the starches liquid absorption and thickening properties. Browning flour develops in the crust of baked goods, breakfast cereals and fried-batter dipped foods when simple sugars combined with proteins are subjected to temperatures greater than 120ยบC.
Carbohydrates Can Ferment Simple Sugars can be fermented with the addition of yeast, to produce alcohol and carbon dioxide. This process is used to make yeast dough, fermented wine and brew beer. Bacterial action in milk changes simple sugars to lactic acid, a useful process in the production of yoghurt, sour cream, cheese, sauerkraut and raw sausages.
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Effects of Fat in Cooking Fat Dissolves Certain Substances Fat is not water-soluble and thus cannot be mixed with water, since it contains no water-binding molecules. Fat can however be dissolved with certain solutions (gasoline, alcohol). This process is applied when fats or oils are extracted. Fat themselves are capable of absorbing the fat-soluble vitamins A,D,E,K and some color pigments. This process is applied in kitchens when seafood shells are boiled and made into lobster and shrimps butter or crab oil.
Fat Improves Taste Most dishes can be improved with the addition of fats (e.g. fats with noodles, potatoes, rice, or vegetables, oil in salads, cream with some sauces, soups and crèmes), because most flavor substances are fat-soluble. Dough becomes smoother and more elastic with added fat and pastries become moister and shorter in texture (don’t expand during baking process).
Fat is Lighter than Water Fats are less dense than water; therefore, fats float as small droplets in stocks, soups and sauces. Hot fat is removed by careful skimming; in order to defeat a product completely, it must be thoroughly chilled. The hardened fat can then be removed.
Fat Has a High Smoke Point Fats are ideal to produce nicely browned food at 120 ºC. Not all fats however, can be used to roast, sauté, grill or deep-fry, because they heat differently. Fats start to smoke and break down at a certain temperature, which is called the smoke point. Fats that disintegrate above the smoke point can cause health problems, and products fried in this fat are dangerous and not safe for consumption.
Fats Conducts Heat Evenly This characteristic of fats is demonstrated in the deep-fat fryer, where the
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product browns evenly.
Fat Separates Substances This quality is useful in the kitchen when molds and sheet pans are oiled. Puff-pastry layers are created when fat separates the various dough layers. Water in fat turns to steam and forces the dough apart. If the dough is rolled out too thin or unevenly, and the fat layers are too thin or damaged, they will no longer separate the layers, and the puff-pastry will be uneven or only partially puffed.
Fat Has a Melting Point The temperature at which fat changes from solid to liquid is called the melting point. Cooking fats and oils are often mixtures of fatty acids with different melting points. They do not melt at a specific point but at several. In specialized commercial fats, this is accomplished to increase the smoke point of fats.
Fat Inhibits Egg Whites from Foaming Perfectly Fatty acids destroy the formation and stability of beaten egg-white foams. Bowls and whisks should be immaculately clean and free of fat. Egg yolk, which is high in fat, should be completely separated from the egg white. Even a minute residue of detergent can influence the formation of perfectly beaten egg whites.
Fat Can be Emulsified A permanent mixture of fat and water is called an emulsion. The creation of an emulsion requires the presence of amalgamators. In the production of mayonnaise or hollandaise, the lecithin and proteins of egg yolk act as amalgamators; the protein in meats is the amalgamator for pates and farces. Milk, cream, butter and margarine are also emulsions.
Fat Spoils Easily Fat spoils when fatty acids and glycerol separate. This process occurs when fat is exposed to light (ultraviolet rays), heat, moisture, air (Oxygen), minerals (iron and copper), and microorganism. 18
Fat with high water content and fatty acids spoil especially rapidly.
Effects of Protein in Cooking Proteins are Soluble In water: This property is useful when clarifying broth with lean ground meat, when soaking sweetbreads, brains, and bone marrow. Protein foods should never be left in water for long period.
1) - In 2 to 3 % salt solution: When chopping and blending meat or fish for a farce, salt is needed to extract globulin to facilitate proper binding of the mixture.
2) - By simmering in hot water: Bones, cartilage, tendon, rinds, fish bones and the like contain large amount of collagen, a glue-like protein, which can be infused into the stock through long simmering. Cooking time can be shortened when acid is added to the stock. Proteins Swell Protein can bind with water.
3) - Through water absorption: Legumes (dry) must expand to become soft. For this reason, legumes must be started of in cold water when cooking or must be soaked first. Yeast breads, pate dough and spaetzli dough are kneaded or beaten hard to strengthen the gluten and improve the absorption of water. Farces and boiled sausages become juicy when cooked in water. Meats with a high percentage of connective tissue absorb liquid during the slow cooking (stewing, braising, simmering), so that the collagen is softened into gelatin. For this reason, goulash made with hindquarter (high connective tissue) is juicy and tender.
4) - Through acidic action: Marinating with vinegar or wine mixture causes muscle fiber to become firm, 19
while the collagen in the connective tissue expand and becomes gelatinous and tender.
Proteins Foam When egg white is beaten it will foam, which is useful in the preparation of sponge cake, sabayon, whipped egg in dessert creams and puddings.
Proteins Coagulate A - With heat: Starting at 60ºC. This can be observed as skin forms on milk and foam develops when cooking legumes, potatoes, meat, bones and the like. Proteins form foam when butter is heated. When proteins coagulate, they absorb water. Coagulation cannot be reversed. When protein coagulate, they absorb or bind other food. This property is helpful:
Hard-cooked eggs become firm Farces and boiled and blood sausages can be sliced Gluten gives structure to breads and baked goods With cooking meat, fish, vegetables and grain products Crèmes, ice creams, savory egg custard (Royal), puddings can be bound. When soups and sauces are thickened with blood. Consommé and aspic can be clarified.
B - With acid: This process is helpful in the production of yogurt, sour cream, some cheeses and other sour milk products With rennet. This quick method of coagulation is used in the production of most cheese. Because enzymes can break down coagulated proteins more quickly, the human body digests them more easily.
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Disadvantage of Protein Coagulation At temperature above 80ºC, protein can curdle or disintegrate, for example, in soups and sauces and crèmes made with egg yolk, liaison or blood; also savory egg custards and flans collapse. Meat proteins coagulate between 60 to 75ºC and gives off moisture. Meats with little connective tissue will become dry if cooked too long.
Proteins Brown at High Temperature When meat, fish or fowl is roasted, sautéed, grilled, deep fat fried or gratinated, flavor and browning agents form. The protein content of butter makes it possible to brown butter at about 120ºC.
Protein Spoil Rapidly Foods with high protein content spoil rapidly through enzyme action and the presence of microorganisms. Decomposed proteins can be harmful, even poisonous.
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Preservation Methods Preservation means prolonging the shelf life of foods for short or long periods. The goal of the various preservation methods is to kill the microorganisms that cause spoilage, fermentation, and mold growth and to kill and slow down the food’s own enzymes. Several methods may be used at the same time or one after the other. Depending on the type of preservation, the process can be physical or chemical.
Physical Process Lowering of temperature Refrigeration, freezing Heating Pasteurizing, hot-packing, sterilization, UHT Dehydration Drying, heat-drying, freeze-drying, reducing Oxygen removal Vacuum-packing, coating Filtering Radiation
Chemical Process
Salting Curing Smoking Sugaring Pickling
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Refrigeration Effect:
Freezing temperature (for most foods below 5ºC) stop micro organisms from growing and prevents enzyme activity.
Use:
Most foods, except non-perishables and canned goods.
Refrigeration Rules: Cooked foods must be chilled quickly and held at refrigerator temperatures; otherwise sanitation laws are violated. Temperature and relative humidity should be regulated, or quality will be effected. Storage time should be monitored, or spoilage will occur. Temperature fluctuation should be avoided. Refrigerator and freezer doors should not be opened unnecessarily to prevent condensation, which may cause growth of microorganisms. Open refrigerators also increase energy cost. Foods that easily absorb flavors and foods with strong odors should be refrigerated or stored in tightly sealed containers to prevent flavor absorption. Stocks, soups and sauces should be covered and placed in shallow containers the chill them rapidly, to prevent evaporation and bacterial growth.
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Freezing Freezing is the most long-term preservation method for fresh or prepared foods. The food should be blast-frozen to -18ºC or colder to rapidly chill the food to its core. Water is the major ingredient in most foods that are to be frozen. The water is present in unsaturated solutions of salt, sugar, acids and other soluble materials, and is partially available free in cells or cell membranes. It is important to freeze the molecules as rapidly as possible to form tiny ice particles. If the freezing process is slow, water forms large crystals that break the cell structure of the product. The thawed product will lose valuable nutrients, flavor and texture. The activity of microorganisms stops when the water in food freezes. Even cold-loving bacteria stop growing at -15ºC.
Prerequisites for Good Frozen Products The food products must be suitable for freezing. Only fresh raw ingredients should be used. Correct preparation methods ensure that the foods are appropriately partially or fully fried and cooked before freezing. It is important to use nutrient-saving methods and work under strict sanitary conditions. Portioned and individually frozen products are easier to use than large pieces. Vacuum-sealed packaging protects foods from drying out and prevents freezer burn. Volume freezing requires very cold temperatures, -30ºC or colder. Quickly freezing at very low temperatures prevents the formation of large ice crystals, which occur in temperatures between -5º - 0ºC. From the moment of freezing to the time of usage, frozen foods should be continuously kept at temperatures between -22º and -18ºC.
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Guidelines for Proper freezing Pre-preparation Vegetables should be harvested fresh. They are trimmed, blanched, drip-dried and chilled. Blanching destroys enzymes that may cause discoloring or an off-flavor. Vegetables that are not blanched are cucumbers, zucchini, bell peppers, tomatoes and fresh herbs. Fruit should be ripe. Berries can be individually quick-frozen or frozen with sugar and sugar syrup. Stone fruits are usually blanched in water to which sugar and lemon juice has been added. Peaches are peeled and cut. Apricots are cut into halves and individually frozen. Meat, poultry and game should be aged when necessary and stored and handled the same as fresh prepared meats. It is best to freeze in pan-ready portion sizes. Fish should be freshly caught. They are scaled, gutted and washed. They can be frozen whole, portioned or filleted and glazed to prevent drying. Partially or fully prepared foods should be prepared with little fat, since fat effects the storage times. Flour-thickened sauces will become runny and should be bound after thawing. Prepared foods should be quickly chilled and frozen immediately. The dough recipes of baked goods need not to be altered, except for yeast dough. The amount of yeast must be increased, since it loses some of its strength when frozen. Small pastries should be frozen within thirty minutes, larger baked goods within two hours.
Packaging All foods should be wrapped carefully. The wrapping must be approved for food use; freezer strength, resistant to fat and acids, strong and impermeable to water vapors and oxygen. The best method is vacuum packing, because air pockets insulate and might slowdown the freezing process. In addition, air contains microorganisms that will become active when the food is thawed, and so might spoil the food.
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Correct Freezing Freezing equipment is set at lowest possible temperature. Freezing capacity should not be exceeded. Frozen goods are shaped into flat packages to promote rapid freezing. Packages are placed directly on cooling coils or surfaces. Packages are spaced to allow air to circulate around each product. One can stack products only after they are completely frozen. All packages are labeled with content and production or preparation date.
Storage Times Most foods can be frozen successfully. Storage time depends largely on the type and fat content of the food. High-fat foods become rancid after a short while, because fat-destroying enzymes are still active at freezing temperatures. A minimum temperature of -18ºC MUST be maintained and should be checked twice daily.
Thawing of Frozen Products Principally for sanitary reasons, all frozen foods should be thawed under refrigeration. Poultry wrappers are removed before thawing and poultry is placed in pans to prevent dripping (salmonella danger) and cross contamination of other food products. Water conducts heat more quickly than air and will thus thaw food products much faster. This method, however, can only be used with cold running water, for vacuum-packed products.
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Preparation of Frozen Foods Vegetables Vegetables frozen in a solid block must be fully or at least partially thawed before cooking. Individually frozen vegetables are best cooked unthawed. Cooking times for frozen vegetables should be reduced by 30 to 50 percent, because they have already been blanched.
Fruits Fruits used in cooking and baking should remain unthawed. Fruits that are consumed uncooked should be covered while thawing.
Meat, Game and Poultry Meat, game, and poultry are best thawed slowly under refrigeration. The cooking process can be better controlled this way. Very small pieces can be used frozen, partially or fully thawed, depending on the preparation method.
Fish Fish should be partially thawed to make the separation of fillets and portioning possible. Breaded frozen fish portions should not be thawed, as they will turn soggy.
Cooked Potatoes Cooked potatoes, for example, French fries, should be deep-fried while still frozen. Defrosting adds water to the deep fryer, which causes the fat to foam and spatter. Baskets should not be overfilled.
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Convenience Foods The trend toward the use of prepared and manufactured food products has strongly increased, as life-styles change. These are the convenience foods – foods that make food preparation easier and are convenient to use. These food products reduce labor by already being washed, trimmed, cooked, spiced, and preserved. Convenience foods are not really new. Even earlier generations relied on others to do some of the work, for example, the grinding of grain, the baking of bread, the production of pasta etc.
Working with Convenience Foods Convenience Foods as Basic Ingredients Many convenience foods are basic products that can and should be individually improved, refined, and spiced.
Follow Directions Carefully Preparation instructions should be read carefully. Information about measures, cooking times, and preparation should be followed exactly.
Short Cooking Times Convenience sauces and soups have a very short cooking time. Long, unnecessary cooking will affect quality and cause them to thin.
Precise Measures Properties between mass and water must be exactly measured or weighed. Guesses are not appropriate and will produce poor results.
Solubility of Powdered Sauces and Soups Sauces and soups, depending on instructions, can be dissolved in cold or hot water, and then cooked.
Instant Foods Instant foods will not lump and can be easily dissolved in hot or cold liquid. Paste products can be used to taste.
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Partial Use It is important to mix the ingredients thoroughly if only a partial package is needed. Partially used packages must be properly sealed and stored in a dry, cool space. Convenience foods are helpful in the kitchen. Used sparingly and individually refined, they are a help and a challenge to cook. However, establishments that primarily use convenience foods are not places to teach professional cooking skills to apprentices.
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Part Two: Basic Cooking Methods Course Objectives After completion of Part Two “Basic Cooking Methods” you should: Understand the Importance of Mastering the Technical Skills of all Cooking Methods Understand the Basic Principles of all Cooking Methods Know the preferred Cooking Methods to use with each Food Product
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Part Two: Basic Cooking Methods Course Contents Introduction Knowledge of Basic Cooking Techniques is Essential
Basic Cooking Methods
Blanching Boiling Simmering Steaming Poaching Sautéing Stir-frying Stewing Deep-frying Pan-frying Broiling Grilling Gratinating, au Gratin Baking Glazing Roasting Butter Roasting Braising
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Introduction Basic Cooking Methods Knowledge of the physical and chemical processes in cooking is essential for anyone working in food preparation to ensure a consistent quality of end product with a minimum loss of taste and nutrients. Foods can be cooked in air, fat, water or steam. These are collectively known as cooking media. All 18 basic cooking methods can be categorized under three main types using either: dry heat or moist heat. Knowledge of the 18 basic cooking methods guarantees error-free mastery of all cooking processes. Only after understanding and using these basic techniques can one create dishes that are more complicated. All recipes always include one or several of the 18 basic cooking methods in some way. Dry-heat cooking methods are those using air or fat. They are gratinating, broiling, grilling, roasting, butter roasting and baking, sautĂŠing, stir-frying, pan-frying and deep-frying. Foods cooked using dry-heat cooking methods have a rich flavor caused by browning. Moist-heat cooking methods are those using water or steam. They are glazing, poaching, simmering, boiling, blanching and steaming. Moist-heat cooking methods are used to tenderize and emphasize the natural flavors of food. Other cooking methods employ a combination of dry- and moist-heat cooking methods. The two most significant of these combination cooking methods are braising and stewing. Each of these cooking methods can be applied to a wide variety of foodsmeats, fish, vegetables and even pastries.
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Dry-heat Cooking Methods Cooking by dry heat is the process of applying heat either directly, by subjecting the food to the heat of a flame, or indirectly, by surrounding the food with heated air or heated fat.
Broiling Broiling uses radiant heat from an overhead source to cook foods. The temperature at the heat source can be as high as 1093°C. The food to be broiled is placed on a preheated metal grate. Radiant heat from overhead cooks the food, while the hot grate below marks it with attractive crosshatch marks. Delicate foods that may be damaged by being placed directly on a metal grate or foods on which crosshatch marks are not desirable may be placed on a pre-heated heatproof platter and then placed under the broiler. Cooking will take place through indirect heat from the preheated platter as well as by direct heat from the broiler's overhead heat source.
ďƒ˜ Procedure for Broiling Foods 1. Heat the broiler or salamander. If necessary, use a wire brush to remove any charred or burnt particles that may be stuck to the broiler grate. The grate can be wiped with a lightly oiled towel to remove any remaining particles and to help season it. 2. Cut, trim or otherwise prepare the food to be broiled. Marinate, rub or season it, as desired. Many foods can be brushed lightly with oil to keep them from sticking to the grate. 3. Place the food in the broiler, presentation side down. If necessary, use tongs to turn or flip the item without piercing its surface. 4. Cook the food to the desired degree of doneness while developing the proper surface color. To do so, adjust the position of the item on the broiler, or adjust the distance between the grate and heat source. Doneness is often determined by touch or specific visual cues (for example, clear juices running from poultry).
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Preheat the grate under the broiler, then pull it out and place the food on the hot grate, presentation side down. If the item is oblong, place it at a 45degree angle to the bars on the cooking grate. Slide the grate back under the broiler and cook long enough for the food to develop lines where it touches the grate. Pull the sliding grate out again and turn the food over at a 90degree angle working from left to right.
Pull the sliding grate out of the broiler to turn the food as necessary in order to cook it evenly. Note the handle visible on the right, which can be used to adjust the distance between the grate and the heat source.
Remove the cooked item from the broiler grate.
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Grilling Although similar to broiling, grilling uses heat source located beneath the cooking surface. Grills may be electric or gas, or they can burn wood or charcoal, which will add a smoky flavor to the food. Specific woods such as mesquite, hickory or vine clippings can be used to create special flavors. Grilled foods are often identified by crosshatch markings.
ďƒ˜ Procedure for Grilling Foods 1. Heat the grill. 2. If necessary, use a wire brush to remove any charred or burnt particles that may be stuck to the grill grate. The grate can be wiped with a lightly oiled towel to remove any remaining particles and to help season it. 3. Cut, trim or otherwise prepare the food to be grilled. Marinate, rub or season it, as desired. Many foods can be brushed lightly with oil to keep them from sticking to the grate. 4. Place the food on the grill, presentation side down. If practical, rotate the food 90 degrees to produce the attractive crosshatch marks associated with grilling. Then use tongs to turn or flip the item without piercing its surface. 5. Cook the food to the desired degree of doneness while developing the proper surface color. To do so, adjust the position of the item on the grill, or adjust the distance between the grate and heat source. Doneness is often determined by touch or specific visual cues (for example, clear juices running from poultry).
Decide which side of the grilled food will be presented face up to the customer. Place the food on the hot grill with this side facing down. If the item is oblong, place it at a 45-degree angle to the bars on the cooking grate. Cook long enough for the food to develop dark charred lines where it touches the grate.
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Rotate the food 90 degrees and allow it to cook long enough for the grates to char it to the same extent as in Step 1.
Turn the food over and finish cooking it. It is usually unnecessary to create the crosshatch markings on the reverse side because the customer will not see this side.
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Roasting and Baking Roasting and baking are the processes of surrounding a food with dry, heated air in a closed environment. The term roasting is usually applied to meats and poultry, while baking is used when referring to fish, fruits, vegetables, starches, breads and pastry items. Heat is transferred by convection to the food's surface and then penetrates the food by conduction. The surface dehydrates and the food browns from caramelization, completing the cooking process. Poêléing (poe-el-lay-ing) is a cooking method similar to both roasting and braising. The food is cooked in an oven, but in a covered pot with aromatic vegetables and bacon fat or butter, so that it steams in its own juices. Also known as butter roasting, the French poêlé technique is perhaps most similar to pot-roasting. Like a typical roasted dish (and unlike a typical braised dish), this method is used for tender cuts of meats and poultry that do not require long, slow cooking, and no additional liquid is added during cooking. The meat or poultry can first be browned in hot fat or it can be browned toward the end of cooking by removing the lid of the cooking vessel. Doneness is determined using the same techniques as those used for roasting. The meat or poultry is usually served with a sauce made from the pan juices mixed with a liquid and finished in the same way as a sauce for a braised dish.
Procedure for Roasting or Baking Foods 1. Preheat the oven. 2. Cut, trim or otherwise prepare the food to be roasted or baked. Marinate or season as desired. Brush with oil or butter, as appropriate. 3. Place the food on a rack or directly in a roasting pan or baking dish. 4. Roast the food, generally uncovered, at the desired temperature. Baste as necessary. 5. Cook to the desired internal temperature or doneness, remembering that many foods will undergo carryover cooking after they are removed from the oven.
Season the item to be roasted, arrange it in an uncovered pan and place it in a preheated oven.
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Use a thermometer to check the internal temperature of the item being roasted.
Terminology Baste Baste is to moisten foods during cooking (usually grilling, broiling or roasting) with melted fat, pan drippings, a sauce or other liquids to prevent drying and to add flavor Terminology Carryover Cooking Carryover Cooking the cooking that occurs after a food is removed from a heat source; it is accomplished by the residual heat remaining in the food.
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Sautéing Sautéing is a dry-heat cooking method that uses conduction to transfer heat from a hot sauté pan to food with the aid of a small amount of fat. Heat then penetrates the food through conduction. High temperatures are used to sauté, and the foods are usually cut into small pieces to promote even cooking. To sauté foods properly, begin by heating a sauté pan on the stove top, then add a small amount of fat. The fat should just cover the bottom of the pan. Heat the fat to the point where it just begins to smoke. The food to be cooked should be as dry as possible when it is added to the pan to promote browning and to prevent excessive spattering. Place the food in the pan in a single layer. (The pan should be just large enough to hold the food in a single layer; a pan that is too large may cause the fat to burn.) The heat should be adjusted so that the food cooks thoroughly; it should not be so hot that the outside of the food burns before the inside is cooked. The food should be turned or tossed periodically to develop the proper color. Larger items should be turned using tongs without piercing the surface. Smaller items are often turned by using the sauteuse's sloped sides to flip them back on top of themselves. When tossing sautéed foods, keep the pan in contact with the heat source as much as possible to prevent it from cooling. Sautéing sometimes includes the preparation of a sauce directly in the pan after the main item has been removed. Stir-frying is a variation of sautéing. A wok is used instead of a sauté pan; the curved sides and rounded bottom of the wok diffuse heat efficiently and facilitate tossing and stirring. Otherwise, stir-frying procedures are the same as those outlined for sautéing and will not be discussed separately here.
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Procedure for Sautéing Foods 1. Cut, pound or otherwise prepare the food to be sautéed. Season and dredge it in flour, if desired. 2. Heat a sauté pan and add enough fat (typically, oil or clarified butter) to just cover the pan's bottom. 3. Add the food to the sauté pan in a single layer, presentation side down. Do not crowd the pan. 4. Adjust the temperature so that the food's exterior browns properly without burning and the interior cooks. The heat should be high enough to complete the cooking process before the food begins to stew in its own juices. 5. Turn or toss the food as needed. Avoid burns by not splashing hot fat. 6. Cook until done. Doneness is usually determined by timing or touch.
Heat a small amount of oil in the sauté pan before adding the food.
The sloped edge of the pan can be used to toss the food. The item being sautéed should be cooked quickly.
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Pan-Frying Pan-frying shares similarities with both sautéing and deep-frying. It is a dry-heat cooking method in which heat is transferred by conduction from the pan to the food, using a moderate amount of fat. Heat is also transferred to the food from the hot fat by convection. Foods to be pan-fried are usually coated in breading. This forms a seal that keeps the food moist and prevents the hot fat from penetrating the food and causing it to become greasy. To pan-fry foods properly, first heat the fat in a sauté pan. Use enough fat so that when the food to be cooked is added, the fat comes one-third to halfway up the item being cooked. The fat should be at a temperature somewhat lower than that used for sautéing; it should not smoke but should be hot enough so that when the food is added it crackles and spatters from the rapid vaporization of moisture. If the temperature is too low, the food will absorb excessive amounts of fat; if it is too high, the food will burn on the outside before the interior is fully cooked. When the food is properly browned on one side, use tongs to turn it without piercing. Always turn the food away from you to prevent being burned by any fat that may splash. When the food is fully cooked, remove it from the pan, drain it on absorbent paper and serve it immediately.
Procedure for Pan-frying Foods 1. Cut, pound or otherwise prepare the food to be pan-fried; then bread, batter or flour it as desired. 2. Heat a moderate amount of fat or oil in a heavy pan-usually enough to cover the item one-third to halfway up its sides. 3. Add the food to the pan, being careful not to splash the hot fat. 4. Fry the food on one side until brown. Using tongs, turn and brown the other side. Generally, pan-fried foods are fully cooked when they are well browned on both sides. 5. Remove the food from the pan and drain it on absorbent paper before serving.
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Use tongs to carefully place the item being pan-fried into a moderate amount of hot oil.
Turn the item to brown the other side.
Drain the cooked item on absorbent paper.
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Deep-frying Deep-frying is a dry-heat cooking method that uses conduction and convection to transfer heat to food submerged in hot fat. Although conceptually similar to boiling, deep-frying is not a moist-heat cooking method because the liquid fat contains no water. A key difference between boiling and deep-frying is the temperature of the cooking medium. The boiling point, 100°C, is the hottest temperature at which food can be cooked in water. At this temperature, most foods require a long cooking period and surface sugars cannot caramelize. With deepfrying, temperatures up to 180°C are used. These high temperatures cook food more quickly and allow the food's surface to brown. Foods to be deep-fried are usually first coated in batter or breading. This preserves moisture and prevents the food from absorbing excessive quantities of fat. Foods to be deep-fried should be of a size and shape that allows them to float freely in the fat. Foods that are to be deep-fried together should be of uniform size and shape. Delicately flavored foods should not be deep-fried in the same fat used for more strongly flavored ones, as the former could develop an odd taste from residual flavors left in the fat. Deep-fried foods should cook thoroughly while developing an attractive deep golden-brown color. Today, most deep-frying is done in specially designed commercial fryers. These deep-fat fryers have built-in thermostats, making temperature control more precise. Deep-frying foods in a saucepan on the stove top is discouraged because it is both difficult and dangerous. Recovery time is usually very slow, and temperatures are difficult to control. Also, the fat can spill easily, leading to injuries or creating a fire hazard.
Terminology Recovery Time Recovery time is the length of time it takes a cooking medium such as fat or water to return to the desired cooking temperature after food is submerged in it.
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To deep-fry food, first heat the fat or oil to a temperature between 160oC and 180oC. The cooking medium's temperature can be adjusted within this range to allow the interior of thicker foods or frozen foods to cook before their surfaces become too dark. The fat must be hot enough to quickly seal the surface of the food so that it does not become excessively greasy, yet it should not be so hot that the food's surface burns before the interior is cooked. There are two methods of deep-frying:  Basket method  Swimming method The basket method uses a basket to hold foods that are breaded, are individually quick-frozen or otherwise will not tend to stick together during cooking. The basket is removed from the fryer and filled as much as twothirds full of product. (Do not fill the basket while it is hanging over the fat, as this allows unnecessary salt and food particles to fall into the fat, shortening its life.) The filled basket is then submerged in the hot fat. When cooking is completed, the basket is used to remove the foods from the fat and hold them while excess fat drains off. A variation on this procedure is the double-basket method. It is used because many foods float as they deep-fry. This may produce undesirable results because the portion of the food not submerged may not cook. To prevent this and to promote even cooking, a second basket is placed over the food held in the first basket, keeping the food submerged in the fat. Most battered foods initially sink to the bottom when placed in hot fat, then rise to the top as they cook. Because they would stick to a basket, the swimming method is used for these foods. With the swimming method, battered foods are carefully dropped directly into thy hot fat. (Baskets are not used.) They will rise to the top as they cook. When the surface that is in contact with the fat is properly browned, the food is turned over with a spider or a pair of tongs so that it can cook evenly on both sides. When done, the product is removed and drained, again using a spider or tongs.
The basket method of deep-frying. The double-basket method The swimming method of deep-frying. deep-frying.
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ďƒ— Procedure for Deep-frying Foods 1. Cut, trim or otherwise prepare the food to be deep-fried. Bread or batter it, as desired. 2. Heat the oil or fat to the desired temperature. 3. Using either the basket method or the swimming method, carefully place the food in the hot fat. 4. Deep-fry the food until done. Doneness is usually determined by timing, surface color or sampling. 5. Remove the deep-fried food from the fryer and hold it over the cooking fat, allowing the excess fat to drain off. 6. Transfer the food to a hotel pan either lined with absorbent paper or fitted with a rack. 7. If the deep-fried items are to be held for later service, place them under a heat lamp; steam tables will not keep fried foods properly hot.
Fats for Deep-Frying Many types of fats can be used for deep-frying. Although animal fats, such as rendered beef fat, are sometimes used to impart their specific flavors to deep-fried foods: their low smoke points generally make them unsuitable for deep-frying unless blended with vegetable fats. By far the most common fats used for deep-frying are vegetable oils such as soybean, peanut and canola oil, all of which have high smoke points and are relatively inexpensive. Specially formulated deep-frying compounds are also available. These are usually composed of a vegetable oil or oils to which antifoaming agents, antioxidants and preservatives have been added. These additives increase the oil's usable life and raise its smoke point. Deep-fryer fats may also be hydrogenated. Hydrogenation is a chemical process that adds hydrogen to oil, turning the liquid oil into a solid (margarine is hydrogenated vegetable oil). Hydrogenated fats are more resistant to oxidation and chemical breakdown. To choose the right fat, consider flavor, smoke point and resistance to chemical breakdown. High-quality frying fat should have a clean or natural flavor and a high smoke point and, when properly maintained, should be resistant to chemical breakdown.
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Reaction Temperatures on Fats: Fat Melt Point Smoke Point Flash Point Butter 33-36oC 127oC Possible at any temperature above 150oC Butter, clarified 33-36oC 168-193oC Possible at any temperature above 150oC Lard 23-36 oC 188 oC n/a o o Deep-fryer shortening, 39 C 227 C 365 oC heavy-duty, premium Canola oil n/a 220-230 oC 275-290 oC Corn oil 5-7 oC 210 oC 321 oC Cocoa butter 31-34oC n/a n/a o o Cottonseed oil 13 C 232 C 343 oC Margarine 34-36 oC 210-221oC Possible at any temperature above 150oC Olive oil, extra virgin 0 oC 121 oC n/a o o Olive oil, pure or 0 C 210 C 225 oC pomace Peanut oil -2 oC 232 oC 283 oC o o Shortening, vegetable, 49 C 210 C 329 oC all-purpose Soybean oil 20 oC 257 oC 282 oC o Walnut oil n/a 232 C 326 oC The data was compiled from a variety of sources and is meant as a guideline only. Because reaction temperatures depend on the exact type and ratio of fatty acids present, the actual temperatures will vary depending on the brand or manufacturer of the fat in question. Temperatures are for clean, previously unused fats. Heating a fat, even one time, can lower the smoke and flash points dramatically. Note: n/a = not available
Properly maintaining deep-fryer fat will greatly extend its useful life. To do so: 1. Store the fat in tightly sealed containers away from strong light; cover the deep fryer when not in use. Prolonged exposure to air and light turns fat rancid. 2. Skim and remove food particles from the fat's surface during frying. Food particles cause fat to break down; if they are not removed, they will accumulate in the fryer and burn. 3. Do not salt food over the fat. Salt causes fat to break down chemically. 4. Prevent excessive water from coming into contact with the fat; pat-dry moist foods as much as possible before cooking and dry the fryer, baskets and utensils well after cleaning. Water, like salt, causes fat to break down. 5. Do not overheat the fat (turn the fryer down or off if not in use). High temperatures break down the fat. 6. Filter the fat each day or after each shift if the fryer is heavily used. Best
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results are obtained by using a filtering machine designed specifically for this purpose. Many large commercial fryers even have built-in filter systems. Less well-equipped operations can simply pour the hot fat through a paper filter. Fryer Fat can be damaged by: Salt Water Overheating Food particles Oxygen Change fryer fat when it: Becomes dark Smokes Foams Develops off-flavors
Safety Alert - Cooking with Hot Oil When hot oil comes into contact with liquid, it can spatter, causing severe burns. Use caution when placing foods into hot fat. When pan-frying, slide food into the heated pan, letting it fall away from you so that splatters do not cause burns. Pat moist foods dry with paper towels before adding them to a deep fryer. Oil heated to its flash point can ignite, causing burns or a serious kitchen fire. When oil is heated to its smoke point, it begins to break down creating acreolin, a harsh-smelling chemical compound. This offensive smell is a good warning that hot oil may be close to its flash point. Turn off the heat and carefully remove the pan of oil from its heat source. Allow the oil to cool completely before discarding.
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Moist-heat Cooking Methods Cooking with moist heat is the process of applying heat to food by submerging it directly into a hot liquid, or by exposing it to, steam.
Poaching Poaching is a moist-heat cooking method that uses convection to transfer heat from a liquid to a food. It is most often associated with delicately flavored foods that do not require long cooking times to tenderize them, such as eggs, fruit or-fish. For poaching, the food is placed in a liquid held at temperatures between 71°C and 82°C. The surface of the 1iquid should show only slight movement, but no bubbles. It is important to maintain the desired temperature throughout the cooking process. Do not allow the liquid to reach a boil, because the agitation will cause meats to become tough and stringy and will destroy tender foods such as fresh fruit or fish. The flavor-of the poaching liquid strongly affects the ultimate flavor of the finished product, so stock, court bouillon or broth is generally used. The liquid used to poach a food is sometimes used to make an accompanying sauce. There are two methods of poaching: Submersion poaching Shallow poaching For submersion poaching, the food is completely covered with the cooking liquid. There should not be too much excess liquid, however, as this could leach away much of the food's flavor. Nor should there be too little, as that could leave a portion of the food exposed, preventing it from cooking. For shallow poaching, the food is placed in just enough liquid to come approximately halfway up its sides. The liquid, called a cuisson, is brought to a simmer on the stove top. The pan is then covered with a piece of buttered parchment paper or a lid, and cooking is completed either on the stove top or in the oven. Shallow poaching combines aspects of poaching and steaming.
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ďƒ˜ Procedure for Poaching Foods 1. Cut, trim or otherwise prepare the food to be poached. 2. Bring an adequate amount of cooking liquid to the desired starting temperature. (For some items, the cooking liquid is first brought to a boil and then reduced to the poaching temperature.) Place the food in the liquid. 3. For submersion poaching, the liquid should completely cover the food. 4. For shallow poaching, the liquid should come approximately halfway up the side of the food. If shallow poaching, cover the pan with a piece of buttered parchment paper or a lid. 5. Maintaining the proper temperature, poach the food to the desired doneness in the oven or on the stove top. Doneness is generally determined by timing, internal temperature or tenderness. 6.Remove the food and hold it for service in a portion of the cooking liquid or, using an ice bath, cool it in the cooking liquid. 7. The cooking liquid can sometimes be used to prepare an accompanying sauce or reserved for use in other dishes.
Season the poaching liquid as desired and bring it to the correct temperature.
Carefully place the food item into the poaching liquid.
Remove the cooked food from the poaching liquid.
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Simmering Simmering is another moist-heat cooking method that uses convection to transfer heat from a liquid to a food. It is often associated with foods that need to be tenderized through long, slow, moist cooking, such as less tender cuts of meat. Properly simmered foods should be moist and very tender. For simmering, the food is submerged in a liquid held at temperatures between 85°C and 96°C. Because simmering temperatures are slightly higher than those used for poaching, there should be more action on the liquid's surface, with a few air bubbles breaking through. As with poaching, the liquid used for simmering has a great effect on the food's flavor. Be sure to use a well-flavored stock or broth and to add mirepoix, herbs and seasonings as needed.
ďƒ˜ Procedure for Simmering Foods 1. Cut, trim or otherwise prepare the food to be simmered. 2. Bring an adequate amount of the cooking liquid to the appropriate temperature (some foods, especially smoked or cured items, are started in a cold liquid). There should be enough liquid to cover the food completely. 3. Add the food to the simmering liquid. 4. Maintaining the proper cooking temperature throughout the process, simmer the food to the desired doneness. Doneness is generally determined by timing or tenderness. 5. Remove the item and hold it for service in a portion of the cooking liquid or, using an ice bath, cool the food in its cooking liquid.
The item being simmered should be fully submerged in the seasoned liquid.
Remove the cooked item from the liquid.
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Boiling Boiling is another moist-heat cooking method that uses the process of convection to transfer heat from a liquid to a food. Boiling uses large amounts of rapidly bubbling liquid to cook foods. The turbulent waters and the relatively high temperatures cook foods more quickly than do poaching or simmering. Few foods, however, are cooked by true boiling. Most "boiled" meats are actually simmered. Even "hard-boiled" eggs are really only simmered. Starches such as pasta and potatoes are among the only types of food that are truly boiled. Use as much water as practical when boiling food. Whenever food is added to boiling water, it lowers the water's temperature. The greater the amount of water, however, the faster it will return to a boil.
Poaching 71°C – 82°C
Simmering 85°C - 96°C
Boiling 100°C
Under normal atmospheric pressure at sea level, water boils at 100°C. The addition of other ingredients or a change in atmospheric pressure can change the boiling point, however. As altitude increases, the boiling point de- creases because of the drop in atmospheric pressure. For every 300 meter above sea level, the boiling point of water drops 1oC. On a mountain of 1500 meters height, water boils at 95oC. Because the boiling temperature is lower, it will take longer to cook foods on a mountain than in, for example, Alexandria. The addition of alcohol also lowers the boiling point of water because alcohol boils at about 80°C. In contrast, the addition of salt, sugar or other substances raises the boiling point slightly. This means that foods cooked in salted water cook faster because the boiling point is one or two degrees higher than normal.
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ďƒ˜ Procedure for Boiling Foods 1. Bring an appropriate amount of a liquid to a boil over high heat. Add oil or seasonings, if desired. 2. Add the food to be boiled to the rapidly boiling water. Bring the liquid back to a boil and adjust the temperature to maintain the boil. 3. Cook until done. Doneness is usually determined by timing or texture. 4. Remove the boiled food from the cooking liquid, draining any excess liquid. 5. Serve the boiled food immediately. Some boiled foods can be refreshed in iced water and held for later service.
Bring the cooking liquid to a full boil. When the item being cooked is added to the liquid, its temperature will fall.
After a boiled item such as pasta is cooked, it may be drained through a colander.
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Steaming Steaming is a moist-heat cooking method that uses the process of convection to transfer heat from the steam to the food being cooked. It is most often associated with tender, delicately flavored foods, such as fish and vegetables, which do not require long cooking times, Steaming tends to enhance a food's natural flavor and helps retain its nutrients. Properly steamed foods should be moist and tender. Additional flavor can be introduced by adding wine; stock, aromatics, spices or herbs to the liquid used as the steaming medium. The steaming liquid can also often be used to make a sauce to be served with the steamed food. The food to be steamed is usually placed in a basket or rack above a boiling liquid. The food should not touch the liquid; it should be positioned so that the steam can circulate around it. A lid should be placed on the steaming pot to trap the steam and also create a slight pressure within the pot, which speeds the cooking process. Another type of steaming uses a convection steamer. Convection steamers use pressurized steam to cook food very quickly in an enclosed chamber. Convection steamer cooking does not result in a flavored liquid that can be used to make a sauce. Steamed foods should be served immediately. If held for later service, they should be refreshed and refrigerated until used.
ďƒ˜ Procedure for Steaming Foods 1. Cut, trim or otherwise prepare the food to be steamed. 2. If a convection steamer is not being used, prepare a steaming liquid and bring it to a boil in a covered pan or double boiler. 3. Place the food to be steamed on a rack, in a basket or on a perforated pan in a single layer. Do not crowd the items. Place the rack, basket or pan over the boiling liquid. 4. Alternatively, place the food in a shallow pool of the cooking liquid. 5. Cover the cooking assemblage and cook to the desired doneness. Doneness is usually determined by timing, color or tenderness.
Trim items before steaming them so that they cook evenly.
A perforated hotel pan can be set over a deeper pan of water, covered and used as a steamer.
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Moist-Heat Cooking Methods Method Poaching Simmering Boiling Steaming
Liquid's Liquid's condition temperature 71-82oC Liquid moves slightly but no bubbles o 85-96 C Small bubbles break through the liquid's surface o 100 C Large bubbles and rapid movement o 100 C or Food is in contact only with the higher steam generated by a boiling liquid
Uses Eggs, fish, fruits Meats, stews, chicken Vegetables, pasta Vegetables, fish, shellfish
Combination Cooking Methods Some cooking methods employ both dry-heat and moist-heat cooking techniques. The two principal combination methods are braising and stewing. In both methods, the first step is usually to brown the main item using dry heat. The second step is to complete cooking by simmering the food in a liquid. Combination methods are often used for less tender but lavours l cuts of meat as well as for poultry and some vegetables.
Braising Braised foods benefit from the best qualities of both dry- and moist-heat cooking methods. Foods to be braised are usually large pieces that are first browned in a small amount of fat at high temperatures. As with sautĂŠing, heat is transferred from the pan to the food mainly by the process of conduction. Vegetables and seasonings are added, and enough sauce or liquid is added to come one-third to halfway up the item being cooked. The pan is covered, and the heat is reduced. The food is then cooked at low heat, using a combination of simmering and steaming to transfer heat from the liquid (conduction) and the air (convection) to the food. This can be done on the stove top or in the oven. A long, slow cooking period helps tenderize the main item. Braised foods are usually served with a sauce made from the cooking liquid.
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Procedure for Braising Foods 1. Cut, trim or otherwise prepare the food to be braised. Dredge it in flour, if desired. 2. Heat a small amount of fat in a heavy pan. 3. Sear the food on all sides. Some foods – notably, meats – should be removed from the pan after they are seared. 4. Add any other ingredients and sauté. 5. Add flour or roux, if used. 6. Add the cooking liquid; it should partially cover the food being braised. 7. Add aromatics and seasonings. 8. If the principal item was removed, return it to the pan. 9. Cover the pan and bring the cooking liquid to a simmer. Cook slowly, either on the stove top or in an oven 120°C-150°C. Baste and turn the food as needed. 10. When the principal item is cooked, remove it from the pan and hold it in a warm place. 11. Prepare a sauce from the braising liquid if desired. This may be done by reducing the liquid on the stove top to intensify its lavours. If the food was braised in an unthickened stock, the stock may now be thickened using a roux, arrowroot or cornstarch. Strain the sauce or, if desired, purée the mirepoix and other ingredients and return them to the sauce. Adjust the sauce’s consistency as desired.
First brown the item being braised in fat.
Add liquid to the pan.
The item can be basted with the liquid during cooking.
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Stewing Stewing also uses a combination of dry- and moist-heat cooking methods. Stewing is most often associated with smaller pieces of food that are first cooked either by browning them in a small amount of fat or oil or by blanching them in a liquid. Cooking is then finished in a liquid or sauce. Stewed foods have enough liquid added to cover them completely and are simmered at a constant temperature until tender. Cooking time is generally shorter for stewing than for braising because the main items are smaller.
Procedure for Stewing Foods 1. Trim and cut the food to be stewed into small, uniform-sized pieces. Dredge the pieces in flour, if desired. 2. Heat a small amount of fat in a heavy pan. Then sear the food on all sides, developing color as desired. 3. Add any other ingredients and sauté. 4. Add flour or roux. 5. Gradually add the cooking liquid, stirring to prevent lumps. The liquid should completely cover the principal items. 6. Bring the stew to the appropriate temperature. Cover and place in the oven at 120°C-150°C or continue to simmer on the stove top until the principal items are tender. 7. Remove the principal items and hold them in a warm place. 8. Thicken the sauce as desired. 9. Return the principal items to the stew. If not added during the cooking process, vegetables and other garnishes may be cooked separately and added to the finished stew.
1.First brown the item being stewed in a small amount of fat. 2. Add flour to make a roux.
3. Add liquid to the pan.
4. Degrease the finished stew as necessary.
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Cooking Methods Method Medium Dry-Heat Cooking Methods Broiling Air Grilling Butter Roasting
Air Fat
Roasting Baking Gratinating
Air Air Air
SautĂŠing Fat Stir fry Fat Pan-frying Fat Deep-frying Fat Moist-Heat Cooking Methods Poaching Water or other liquid Simmering
Water or other liquid
Boiling
Water or other liquid
Blanching Water of other liquid Steaming Steam Glazing Water or other liquid Combination Cooking Methods Braising Fat, then liquid Stewing Fat, then liquid
Equipment Overhead broiler, salamander, rotisserie Grill Oven, Covered Pot, Braisière, earthenware Oven Oven Oven, overhead broiler, salamander, GN Insert, ovenproof emaile or earthenware Stove top Stove top, wok Stove top, tilt skillet Deep-fat fryer Stove top, oven, steam-jacketed kettle, tilt skillet Stove top, oven, steam-jacketed kettle, tilt skillet Stove top, oven, steam-jacketed kettle, tilt skillet Stove top, tilt skillet Stove top, convection steamer Stove top, pan with lid Stove top, oven, tilt skillet Stove top, oven, tilt skillet
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Conclusion Cooking is the transfer of heat energy to foods by conduction, convection or radiation. Cooking changes the molecular structure of certain nutrients. When heat is applied, proteins coagulate, starches gelatinize, sugars caramelize, fats melt and water evaporates. Foods can be cooked using a variety of methods. Some use dry heat: broiling, grilling, roasting and baking, sautĂŠing, pan-frying and deepfrying. Others use moist heat: poaching, simmering, boiling and steaming. Still others use a combination of the two: braising and stewing. The method used affects the texture, appearance and flavor of the cooked foods. Students must understand these principles in order to ensure that foods are cooked properly.
Term to Know Cooking Energy Conduction Convection Natural convection Mechanical convection Radiation Infrared cooking Microwave Evaporation Melting Coagulation Gelatinization Caramelization Emulsification Lecithin
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Dissolving Infusing Thickening properties Weeping Lactic acid Smoke point Basting Carryover cooking Recovery time Cuisson Basket-methods Double-basket method Swimming method Shelf life Hydrogenation Preservation Refrigeration Freezing Pasteurization Sterilization Dehydration Vacuum-packing Filtering Salting Curing Smoking Sugaring Pickling Convenience foods
Blanching Boiling Simmering
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Steaming Poaching SautĂŠing Stir-frying Stewing Deep-frying Pan-frying Broiling Grilling Gratinating, au Gratin Baking Glazing Roasting Butter Roasting Braising
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