Food is a source of energy
for all of us. Unhealthy or spoiled food is the major cause of diseases in
humans. This is known as food poisoning.
To prevent this the food needs
to be preserved in a variety of ways .Food preservation is one of the methods
to protect food from unwanted microbial growth. After the food is produced, we
store and protect by covering the rice and curry with lids to keep away flies
and other insects. By this, we are protecting it from any infection caused by
them. This is a short-term condition. Food preservation, on the other hand, is
done to preserve food for a longer time.
Food Preservation Methods
Food preservation started long
back in ancient times. Cooling, freezing, fermentation, sun-drying, etc., are
few age-old food preservation techniques. With the advent of technology, modern
methods of food preservation were developed. Chemicals and other natural
substances were used for preservation. These substances are known as
Salt and edible oils are two
main preservatives which are used since ages to prevent microbial growth. This
is why we add extra oil to pickles. Preservation by salt is known as
salting. Salting helps to preserve fruits for a long term. Meats and fishes can
also be preserved by salting.
Other synthetic preservatives
include vinegar, sodium benzoate, sodium metabisulphite, etc.
Sugar is another common
preservative used in jams and jellies. Sugar is a good moisture absorbent. By
reducing moisture content, it restrains the microbial growth.
Heat and Cold Methods
Boiling and refrigeration
prevent around 70 percent of microbial growth. Boiling kills the microorganisms
that cannot tolerate extreme temperatures. Thus, it helps in food preservation.
Refrigerators have very low
temperatures. Since microbes do not get optimum temperature
they need for growth, their growth is inhibited. Pasteurization developed
by Louis Pasteur is used until today to preserve milk.
Smoking prevents dehydration in fish and meat and
thus prevents spoilage. The wood smoke contains a large number of
anti-microbial compounds that slow the rancidification of animal fats.
The food contents are sealed in an airtight
container at high temperatures. Meat, fish, fruits are preserved by canning.
This method is carried out to remove microbes from
food. For eg., milk sterilization at 100C kills the microbes.
It is the process of removal of water from food. It
is the simplest method and prevents food spoilage by removing water.
This is the process of freezing and dehydration of
the frozen product under vacuum.
This method is also known as cold sterilization.
The UV rays, X rays, gamma rays kill all the unwanted microbes present in food.