An example of a food preservative …

Techniques to prolong the shelf life of a food are called food preservation. We know that microbes proliferate very fast in presence of food, moisture, oxygen and ambient temperature. All the methods of food preservation are aimed at ruling out the food, moisture, oxygen and ambient temperature for microbes so that they won’t proliferate. Some common methods of food preservation are as follows:

Sun Drying: This is a traditional method of food preservation. Sun-drying helps in removing moisture from food. Grains are dried in sun before being stored. Many vegetables are also sun-dried so that they can be used in off season.

Chemical Method: Some chemicals prevent the growth of microorganisms in food. These chemicals are used in pickles and jams to preserve them. Salt, acids and oil are also used as food preservatives. Examples: sodium benzoate and sodium metabisulphate.

Preservation by common salt: When a food item is kept in plenty of salt, water from food comes out because of osmosis. It results in dehydration of the food item. Absence of moisture helps to prevent the growth of microbes. Fish, meat and pickles are preserved by adding salt.

Preservation by Sugar: Sugar preserves food by reducing moisture in food. Jam, jelly and squash are preserved by adding sugar.

Preservation by Oil and Vinegar: The layer of oil on top of food prevents oxygen from entering the food. Some microbes do not survive in absence of oxygen. Some microbes cannot survive in acidic environment and thus vinegar is an effective food preservative.