Methods and principles of food preservation

  • Most kinds of food are readily decomposed by microorganisms unless special methods are used for their preservation.

The chief methods of food preservation are as follows:

  1. Asepsis, or keeping out microorganisms.
  2. Removal of microorganisms.
  3. Maintenance of anaerobic conditions, e.g., in a sealed, evacuated container.
  4. Use of high temperatures.
  5. Use of low temperatures.
  6. Drying; this includes tying up of water by solutes, hydrophilic colloids, etc.
  7. Use of chemical preservatives, either developed by microorganisms or added.
  8. Irradiation
  9. Mechanical destruction of microorganisms, e.g., by grinding, high pressures, etc. (not used industrially).
  10. Combination of two or more of the above methods. Only rarely a single method is effective, and usually several are combined.

Image result for methods of food preservation and principles         Related image

Principles of food preservation

  • The following principles are involved in accomplishing the preservation of food by the various methods:

1.Prevention or delay of microbial decomposition

  • By keeping out microorganisms (asepsis).
  • By removal of microorganisms, e.g., by filtration.
  • By hindering the growth and activity of microorganisms, e.g., by low temperatures, drying, anaerobic conditions, or chemicals.
  • By killing the microorganisms, e.g., by heat or radiation.

2.Prevention or delay of self -decomposition of the food

  • By destruction or inactivation of food enzymes, e.g., by blanching.
  • By prevention or delay of purely chemical reactions, e.g., prevention of oxidation by means of an oxidant.

3.Prevention of damage because of insects, animals, mechanical causes, etc.




Methods and principles of food preservation