Explain how food can be preserved?

There are different ways in which Food can be preserved. Below are some examples of Food Preservation

Drying is one of the most ancient food preservation techniques, which reduces water activity sufficiently to prevent bacterial growth. 

Refrigeration preserves food by slowing down the growth and reproduction of microorganisms and the action of enzymes which cause food to rot.

Pickling is also done to preserve Food for a longer period of time.