Question

Write physical methods of food preservation.

Answer 1

Hint: Food preservation is a term that means increasing the shelf life of the food, in other words, storage of food in such a way that it does not spoil in a shorter time.

Complete answer:
In order to slow down the spoilage process of our food and thus keeping the food fresh for a longer period, many preservation methods have been discovered and are applied to foods.
Different physical methods of preservation of food are as follows:
i. By removal of heat from the food or in other words cooling which involves refrigeration, freezing preservation, etc. By using a freezing method for the preservation of food the storage life of food is increased, like fresh fruits, vegetables, etc. Cooling leads to lowering of temperature which inhibits the growth of microorganisms, including Fungi.
ii. By the addition of heat hence boiling or pasteurizing, it includes pasteurization or sterilization of food. Preservation by heating the food is one of the most common methods that was used earlier. This process has other names such as canning or heat processing. Solid and liquid foods such as milk in factories are preserved by this method as heating kills the microorganisms present in the milk.
iii. By removal of water or in other words, dehydration is one of the efficient methods for preservation which includes, sun drying, freeze-drying, and low-temperature evaporation, water is removed from the food which results in stopping the growth of microorganisms. Example: Fruits, grains, and pulses, etc. and vegetables are even preserved by this method.
iv. UV radiation as High energy electromagnetic radiation or UV radiation is used to prevent the growth of microorganisms in food. The UV radiations are efficient in controlling the growth of microorganisms without inducing radioactivity in food. Example: Bakery products.

Note:
Nowadays, there are many more processes used for preservation one of them is vacuum packaging, as food is stored in packets from which all the air is removed leaving a vacuum, as this is an effective method for food preservation.