Food preservation meaning | Food preservation techniques

FOOD PRESERVATION MEANING

We know that when cooked food or milk is left in a warm and moist place for a long time, it gets spoiled. Food gets spolied due to microbial contamination. Most micro-organism can't grow or multiply when the 

• Condition are dry
• Temperatures is very low
• Temperatures is very high

All methods of food preservation ensure that favourable conditions are not provided for micro-organism to grow and multiply.

The process by which spoliage of food is prevented by using chemical or physical methods is called food preservation.

FOOD PRESERVATION TECHNIQUES

1. Chemical Methods- Food can be preserved by using food preservation. Food preservatives are chemical substances that can check the growth of micro-organism. Most chemical preservatives prevent microbial growth by removing oxygen from the food items.Sodium benzoate, sodium metasulphite and citric acid are common food preservatives. Sodium benzoate is used for preserving fruit juices and squashes. Sodium metabisulphite is used for preserving cut fruits, jams and jellies. Citric acid is used as a preservative in confectionaries.
2. Preservation by common salt- For ages, people have preserved fish are covered with common salt to prevent the growth of microbes. Salting is also used to preserve amla, raw mangoes and tamarind.
3. Preservation by sugar- Jams, jellies and squashes are preserved for a long time because of the presence of sugar in them. Sugar inhibits the growth of food-spoling micro-organism by reducing the moisture content of the food.
4. Preservation by oil and vinegar: Oil and vinegar prevent the growth of food-Spoiling micro-organism. Mustard oil and vinegar are widely used as preservatives for fruits and vagetables in the form of pickles. Meat and fish are also preserved by this method.
5. Pasteurisation- Pasteurisation is a process for preservation of milk. In this method, milk is heated at about 70°c for 15 to 30 Seconds to kill the bacteria present in it and cooled quickly to 10°C to prevent the remain bacteria from growing. The milk is then stored in sterilised bottles or pouches in cold places. Pasteurised milk can be consumed without boiling because it is free from harmful micro-organism. This method was invented by Louis Pasteur in 1862.
6. By Cooling or freezing- Fruits , vagetables, meat and cooked food are kept at low temperature in refrigerator or deep freezers to prevent their spoilage of food by inhibiting the growth of micro-organism.
7. By dehydration- Since moisture is one of the main requirements for microbial growth, removal of water from food materials is an efficient method of food preservation. The process of removal of water from a substance is called dehydration. Sun-drying is atraditional method for preserving food. Wheat, rice and pulses are cleaned and dried in the sunlight. Vagetables like cauliflower, spinach and methi are also preserved in this manner for a long time.

Niwdays dry fruits and vagetables are sold in sealed airtight packets to prevent the attack of microbes.

Advantage of food preservation

1. It decreases the wastage of food by avoiding spoliage.
2. It increases the storage period of food materials.
3. Nutritional value of the food is retained for a long period