Question

Write physical methods of food preservation.

Answer 1

In order to slow down the spoilage process and thus keep foods for a longer period, a wide range of preservation methods are applied to foods. Different physical methods of preservation are used, including.
By removal of heat(cooling): It involves refrigeration, dehydrofreezing preservation or carbocation. By freeze preservation the storage life of food is increased, like fresh fruits, vegetables etc. Cooling leads to lowering of temperature which recents the growth of micro-organisms.
By addition of heat: It includes stationary and agitating pasteurization or sterilization. Preservation by addition of heat is the earliest most common method. It is also known as canning or heat processing. On a large scale, solid and liquid foods such as milk are preserved by this method as heating kills the micro-organisms.
By removal of water(Dehydration): By sun drying, freeze drying and low temperature evaporation, water is removed from the food which results in the prohibition of growth of micro-organisms. Example: Fruits, food grains and various types of vegetables are preserved by this method.
By UV radiation: High energy electromagnetic radiation or UV radiation is used to prevent the growth of micro-organism in food. These radiations control the growth of micro-organisms without inducing radioactivity in food. Example: Bakery products.