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Food preservation techniques


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This document explains about food preservation techniques like pulping, drying, dehydrating and its advantages in preserving food and controlling microorganisms

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Food preservation techniques

  1. 1. Vigyan Ashram Pabal
  2. 2. Techniques of Food Preservation Food Preservation Techniques Thermal Cold Processing Controlling Water Chemicals Chilling Pasteurization Dehydration Preservatives
  3. 3. Thermal Processing Method This 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 time Advantages - Microorganisms like bacteria are killed at temperatures above 82 deg celcius
  4. 4. Removal of heat(Cold Processing) The Food product is subjected to Low temperature around 0 degree Celsius This process can be done through chilling , freezing using refrigerator, Advantages Microbial growth is slowed down Storage life of food product is increased Examples Ice-cream , Cheese
  5. 5. Control of Water In this process, the food product is subjected to dryers By this process, water is removed from the food product Advantages - 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 Examples Use of Dryers for preparing mango powder, dried vegetables
  6. 6. Preservatives They contain a certain chemical composition which controls microorganisms growth They are mainly of 2 types Natural Preservatives Examples :- Salt , Sugar , lemon juice , spice Chemical Preservatives Examples :- Organic and Inorganic foods like Sodium Benzoate , Potassium Meta bisulphate , Citric Acid
  7. 7. Preservatives Natural 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
  8. 8. Preservatives Acids Acids It resists the growth of microorganisms Examples of acids as preservatives: Vinegar or Acetic Acid used for preserving onions Citric acid used for fruit squashes