Cooking is generally understood to be the transfer of heat into food items to render these more palatable, easier digestible and overall speaking, to improve their bacteriological and tasteful aspects.
There are four important reasons why we cook food:

  • To improve the appearance, flavor and taste of food and also helps to develop, blend or alter flavors
  • To bring about structural changes in food.  Meat fibers are tenderized and the cellulose in vegetables and fruits is softened so that they are easier to chew and digest
  • To stimulate the appetite and the digestive juices.  It gives food an attractive appearance, aroma and taste
  • To improve the keeping quality of food. It destroys some of the harmful micro-organisms such as yeasts, and bacteria that are naturally present

Heat Transfer

In order for food to be cooked, heat must be transferred from a heat source (such as a gas flame or an electric element) to and through the food. 
Heat is transferred in three ways: 

Conduction - Heat conducted by fire, hot plate, griddle plate, pot/pan, or grill.
Convection - Heat conducted by hot air, dry and wet steam, water, and oil, as in a steamer or convection oven.
Radiation - Heat conducted by infrared heat or microwaves, as in a broiler, salamander, or microwave oven.

Cooking Methodology

Cooking methods are classified as “moist heat” and “dry heat”.

  • Moist heat methods are those in which the heat is conducted to the food product by water (including stock, sauces, etc) or by steam.
  • Dry heat methods are those in which the heat is conducted without moisture that is by hot air, hot metal, radiation or hot fat.

Moist-Heat Methods

There are number of Moist-Heat Methods. The following section will describe some of them one by one.


To boil means to cook the product fully submerged in liquid that is bubbling rapidly and is greatly agitated. Boiling is generally reserved for certain vegetables and starches. The high temperature would toughen the proteins of meats, fish and eggs and the rapid bubbling breaks up delicate foods. 


To poach means to cook in a liquid, usually a small amount that is hot but not actually bubbling. Temperature is about 71° C to 82°C. Poaching is used to cook delicate foods in a minimum amount of liquid in order to conserve flavor and nutritive value such as fish and eggs out of the shell.


This is the slow cooking of food (simmering) in the smallest quantity of water, stock or sauce in a pan with a tight fitting lid. The cooking temperature is in the range of  120° C - 140° C for better uniformity in cooking, the food is always cut up into small equal sizes and the liquid is always served together so as to provide moisture and taste.