Canning

In canning, the raw food is cleaned  and  prepared carefully. Then, air is removed from it before it is sealed in air tight containers. Finally the containers are heated to a high temperature for a given period of time before they are cooled. Usually meet, fish , milk, poultry and vegetables are heated to about 116°C , while fruits are heated to about 100°c . this process kills any spoilage micro organisms and keep their air away from the food, preventing any chemical changes.

  Canning has no effect on protein , carbohydrate and fat content of food. Most  vitamins are also unaffected except for vitamin C which may be broken down at the high temperature used.