Cooking is the act of preparing food for eating by the application of heat. It encompasses a vast range of methods, tools, and combinations of ingredients to alter the flavor or digestibility of food. It is the general preparation process of selecting, measuring, and combining ingredients in an ordered procedure in an effort to achieve the desired result. Factors affecting the final outcome include the variability of ingredients, ambient conditions, tools, and the skill of the individual doing the actual cooking.
The diversity of cooking worldwide is a reflection of the myriad nutritional, aesthetic, agricultural, economic, cultural, social, and religious considerations that impact upon it.
Applying heat to a food usually, though not always, chemically transforms it, thus changing its flavor, texture, consistency, appearance, and nutritional properties. Other methods of cooking that involve the boiling of liquid in a receptacle have been practiced at least since the 10th millennium BC, when pottery was introduced.
Cooking with a wok in China
A cook sautées onions and green peppers
Effects of Cooking
Proteins
Edible animal material, including muscle, offal, milk, and egg white, contains substantial amounts of protein. Almost all vegetable matter (in particular legumes and seeds) also includes proteins, although generally in smaller amounts, by weight. (When considered as a proportion of total calories, plant foods often contain a greater proportion of protein than animal foods. Broccoli, for example, contains a higher proportion of protein than ground beef.)
These foods may also be a source of essential amino acids. When proteins are heated they become de-natured and change texture. In many cases, the heating causes the structure of the material to become softer or more friable—meat becomes cooked. In some cases, proteins can form more rigid structures, such as the coagulation of albumen in egg whites. The formation of a relatively rigid but flexible matrix from egg white provides an important component of much cake cookery, and also underpins many desserts based on meringue.
Liquids
Cooking often involves water, which is frequently present as other liquids, both added in order to immerse the substances being cooked (typically water, stock, or wine) and released from the foods themselves. Liquids are so important to cooking that the name of the cooking method used may be based on how the liquid is combined with the food, as with the terms steaming, simmering, boiling, braising, and blanching. Heating liquid in an open container results in rapidly increased evaporation, which concentrates the remaining flavor and ingredients; this evaporation is a critical component of both stewing and sauce making.
Fat
Fats and oils come from both animal and plant sources. In cooking, fats provide tastes and textures. When used as the principal cooking medium (rather than water), they also allow the cook access to a wide range of cooking temperatures. Common oil-cooking techniques include sautéing, stir-frying, and deep-frying. Commonly used fats and oils include butter; olive oil; vegetable oils such as sunflower oil, corn oil, and safflower oil; animal fats such as lard, schmaltz, and beef fat (both dripping and tallow); and seed oils such as rapeseed oil (Canola or mustard oil), sesame oil, soybean oil, and peanut oil. The inclusion of fats tends to add flavour to cooked food, even though the taste of the oil on its own is often unpleasant. This fact has encouraged the popularity of high-fat foods, many of which are classified as junk food.
Carbohydrates
Carbohydrates include simple sugars such as glucose (from table sugar) and fructose (from fruit), and starches from sources such as cereal flour, rice, arrowroot, and potatoes. The interaction of heat and carbohydrate is complex.
Long-chain sugars such as starch tend to break down into more simple sugars when cooked, while simple sugars can form syrups. If sugars are heated so that all water of crystallization is driven off, then caramelization starts, with the sugar undergoing thermal decomposition with the formation of carbon, and other breakdown products producing caramel. Similarly, the heating of sugars and proteins elicits the Maillard reaction, a basic flavor-enhancing technique.
An emulsion of starch with fat or water can, when gently heated, provide thickening to the dish being cooked. In European cooking, a mixture of butter and flour called a roux is used to thicken liquids to make stews or sauces. In Asian cooking, a similar effect is obtained from a mixture of rice or corn starch and water. These techniques rely on the properties of starches to create simpler mucilaginous saccharides during cooking, which cause the familiar thickening of sauces. This thickening will break down, however, under additional heat.
Food Safety
Using a chopping board
If heat is used in the preparation of food, it can kill or inactivate potentially harmful organisms including bacteria and viruses. The effect will depend on temperature, cooking time, and technique used. The temperature range from 41 °F to 135 °F (5 °C to 57 °C) is the "food danger zone." Between these temperatures bacteria can grow rapidly. Under optimal conditions, E. coli, for example, can double in number every twenty minutes. The food may not appear any different or spoiled but can be harmful to anyone who eats it. Meat, poultry, dairy products, and other prepared food must be kept outside of the "food danger zone" to remain safe to eat. Refrigeration and freezing do not kill bacteria, but only slow their growth. When cooling hot food, it shouldn’t be left on the side or in a blast chiller (an appliance used to quickly cool food) for more than 90 minutes.
Cutting boards are a potential breeding ground for bacteria, and can be quite hazardous unless safety precautions are taken. Plastic cutting boards are less porous than wood and have conventionally been assumed to be far less likely to harbor bacteria. This notion has been debated, however, and some research has shown wooden boards are far better. Washing and sanitizing cutting boards is highly recommended, especially after use with raw meat, poultry, or seafood. Hot water and soap followed by a rinse with an antibacterial cleaner is effective. (The antibacterial cleaner is often dilute bleach, in a mixture of 1 tbsp per gallon of water. At that dilution bleach is considered food safe, though some professionals choose not to use this method because they believe it could taint some foods). A trip through a dishwasher with a "sanitize" cycle is also an effective method for reducing the risk of illness due to contaminated cooking implements.
External Links
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Cooking."
