Question

What are preservatives? List the various methods of preservation.

Answer 1

Part 1: Preservatives

1. Substances that are added to a food so as to stop or slow down spoilage are called preservatives.
2. The technique to treat a food and increase its shelf life is called food preservation.
3. Preservatives can be salt, sugar, chemical compounds etc.

Part 2: Methods of preservation

1. Heating: Pasteurization is the best technique by which the milk can be preserved for a long duration of time.
2. Cooling: Storing the food at lower temperatures slows the bacterial activity and increase the shelf life of the food.
3. Chemical preservatives: Preservatives like salt and sugar can be added to the food as they inhibit the growth of the bacteria.
4. Drying: Drying removes all the moisture from the food and therefore no bacterial growth will occur.
5. Canning: For long term storage of food, canning is the best method. First boil and later seal pack the food so that no bacterial growth takes place.
6. Freeze drying: The food is frozen and then placed in a vacuum to change the ice crystals directly into vapor form.