Food preservation is very important as it has become a widely applied method in our day to day life. Cooked food, uncooked meat and fish or fruit lose their freshness, become old and spoil in warm, wet air as these undergo changes because of bacteria. Food science and technology have helped us preserve food with their modern techniques. Factories prepare and produce readymade food-meats, fish, peas, fruits. They use certain processes like canning, dehydration, smoke, refrigeration.
Food can be preserved by controlling or destroying the agents like warm and wet air, bacteria, insect and rodents.
Canning is a thermal processing where foods are subjected to high temperatures that are high enough to kill micro-organisms. Foods are sterilized in air tight, heat-resistant pouches.
Dehydration removes water from food and thus prevents bacteria from growing. It then compresses and freeze-dries food which can resume their normal state on rehydration.
Refrigeration helps store foods with nutrients and flavours. But smoke treatment to foods can preserve them only for a short time.
Certain substances in small amounts are added to foods to make them last longer, to give them color and to add flavour to them, to add minerals. They are known as additives. Benzoates, propionic acids, sodium and calcium salts are a few preservatives. Monosodium glutamate, synthetic and aromatic substances add flavour to foods.