Cold temperature helps food stay fresh longer. The basic idea behind refrigeration is to slow down the activity of bacteria (contained in ALL foods) so that it takes longer for the bacteria to spoil the food.

For example, milk will get spoilt in 2-3 hours if it is left out in the open at room temperature. However, by reducing the temperature of the milk, it stays fresh for a week or two -- The cold temperature inside the refrigerator decreases the activity of the bacteria to that extent. Freezing the milk, can stop the bacterial action altogether, and the milk can last for months

Refrigeration and freezing are two of the most common forms of food preservation used today.

Because food is so important to survival, food preservation is one of the oldest technologies used by human beings. It was initially thought of to prevent wastage of food but in today’s hectic life style, a woman has to preserve food more for lack of time than preventing wastage.

Following are the different methods used for food preservation, some domestically and other on a mass scale.

The basic idea behind all forms of food preservation is either:

• to slow down the activity of disease-causing bacteria, or
• to kill the bacteria altogether.

Sterile food is one that contains no bacteria. Unless sterilized and sealed, all food contains bacteria.