Use of high temperature in preservation of food

Heat energy is broadly used for food processing and preservation. In cooking it improves the digestibility of some nutrients, while in other it is accustomed to kill pathogenic microorganisms. Many techniques and processes are during which heat energy is applied within the warm temperature including cooking, blanching, pasteurization and sterilization.

1. Cooking

Cooking involves in heating of food in order to alter its color, flavor and texture. More importantly it improves the digestibility of food components. During this process enzymes and microbes are also killed. Food cooked at home has short life span as these are always left in utensils and are not hermetically sealed and therefore cannot prevent recontamination. Cooked foods have longer shelf life than uncooked ones.

Cooking involves various heating methods such as baking, boiling, braising, broiling, roasting, grilling, frying, stewing, broasting and steaming. Food may be come into direct contact with the food or may be cooked in any suitable medium like water, steam and cooking fats.

·       In boiling, steaming and stewing, the overall process is accomplished by using boiling temperature of water or high if pressure cooker is used. Baking, roasting, broiling use dry heat, while in case of frying, the process is carried out in fat or oil and at a temperature much higher than 100℃ is attained.

Cooking Methods:

·      Baking

It involves cooking in oven having dry heat (100-232℃)

·      Boiling

It involves cooking in liquid, usually water at 100℃

·      Frying

Frying is the cooking in heated fat or oil (160-200℃)

·      Stewing

It involves simmering the food in a small amount of water in a covered saucepan or casserole

·      Steaming

It uses hot steam for cooking (100℃)

·      Roasting

Cooked by a dry heat in oven or closed vessel having a little fat

·      Broiling

 It uses direct rays of heat for cooking of food 

·      Braising

Short frying of food followed by stewing

·      Grilling

Cooking by heat radiations from below or above. 

2.blanching