Food Preservation Techniques

Vigyan Ashram Pabal

Techniques of Food Preservation

Food Preservation Techniques

Thermal

Cold Processing Controlling Water

Chemicals

Chilling

Pasteurization

Dehydration

Preservatives

Thermal Processing MethodThis process of food preservation is related with heating

the food product. This process is also known as heat treatment of food product

Heating is done in range of 85 to 90 deg celcius for some time

Examples:- - Pasteurization of milk - Dipping of vegetables in boiling water for some timeAdvantages - Microorganisms like bacteria are killed at

temperatures above 82 deg celcius

Removal of heat(Cold Processing)The Food product is subjected to Low

temperature around 0 degree CelsiusThis process can be done through chilling ,

freezing using refrigerator,

AdvantagesMicrobial growth is slowed downStorage life of food product is increasedExamples Ice-cream , Cheese

Control of WaterIn this process, the food product is subjected to dryersBy this process, water is removed from the food

productAdvantages- Microorganisms need water for biochemical

reactions hence if water is removed, microorganisms will not grow on food product

- By this process ,microorganisms don’t get free water thus growth of microorganisms is stopped

ExamplesUse of Dryers for preparing mango powder, dried

vegetables

PreservativesThey contain a certain chemical composition

which controls microorganisms growth They are mainly of 2 types

Natural PreservativesExamples :- Salt , Sugar , lemon juice , spice

Chemical PreservativesExamples :- Organic and Inorganic foods like Sodium Benzoate , Potassium Meta bisulphate , Citric Acid

PreservativesNatural Preservatives

Salt It returns water through osmosis process in food

product thus it changes composition of food As a result, no free water is left for microorganisms to

grow

Sugar It absorbs free water from food product thus restricts

growth of microorganisms

Oil and Spices They form a layer over the food product hence it forms a layer between air and microorganisms , thus restricting them

PreservativesAcids

Acids It resists the growth of microorganisms

Examples of acids as preservatives:

Vinegar or Acetic Acid used for preserving onionsCitric acid used for fruit squashes