Food Preservation

To prevent spoilage of food the food is preserved & made germ free by some techniques under food preservation.

(a) Boiling or heating – Boiling water kills bacteria & at increased pressure it kills even spores so the canning industry employes heating to kill bacteria before packing & sealing food.

(b) Salting – Used to preserve the food like fish, pickles etc. for a long time called curing. The biodegradation of food is prevented by this technique.

(c) Drying (Dehydration) – Most microbes cannot grow without water so drying of food by dehydration is an effective method for the preservation of food such as grains, fish, meat, vegetables etc.

(d) Irradiation – This a technique in which food stuffs are sterilize by radioactive radiations without making them radio active. Ultra – violet light is used in bakeries to kill mould spores.

(e) Pasteurization – This is a technique to sterilize milk in which milk is heated up to 60 – 70°C & chilled quickly. Souring bacteria may still present after Pasteurizing milk so keeping the milk sufficiently cool stop the growth of bacteria.

(f) Refrigeration – Microbes can not grow on the freezing point of water so keeping the food stuffs in a refrigerator or in a cool storage is a popular method for preservation of food.

(g) Strong concentration and chemicals – Strong concentration of solute (salt or sugar) causes plasmolysis which leads to death of any bacteria, mould or even creep. Jams, jellies & pickles have higher concentration of sugar or salt due to which they do not
get spoiled. Some time preservatives like sodium benzoate are also added to tinned foods & squashes.