Food preservation  


modified atmosphere

  Food preservation is the process of treating and handling food in a way that preserves its edibility and nutrition value. The main effort is to stop or greatly slow down spoilage to prevent foodborne illness (e.g. salting, cooling, cooking). However some methods utilize benign bacteria, yeasts or fungi to add specific qualities and to preserve food (e.g. cheese, wine). While maintaining or creating nutritional value, texture and flavor is important in preserving its value as food; Preservation usually involves preventing the growth of bacteria, fungi and other micro-organisms, as well as retarding the oxidation of fats which cause rancidity. It also includes processes to inhibit natural ageing and discoloration that can occur during food preparation such as the enzymatic browning reaction in apples which causes browning when apples are cut. Some preservation methods require the food to be sealed after treatment to prevent re-contamination with microbes;

  Common methods of applying these processes include drying, spray drying, freeze drying, freezing, vacuum, canning, preserving in syrup, sugar crystallization, food irradiation, adding preservatives or inert gases such as carbon dioxide. Other methods that not only help to preserve food, but also add flavor, include pickling, salting, smoking, preserving in syrup or alcohol, sugar crystallization and curing.

Preservation processes include:-

  • Heating to kill or denature organisms (e.g. boiling)
  • Oxidation (e.g. use of sulphur dioxide)
  • Toxic inhibition (e.g. smoking, use of carbon dioxide, vinegar, alcohol etc)
  • Dehydration (drying)
  • Osmotic inhibition (e.g. use of syrups)
  • Low temperature inactivation (e.g. freezing)
  • Ultra high water pressure (e.g. fresherized, a kind of“cold” pasteurization, the pressure kills naturally occurring pathogens, whichcause food deterioration)


     One of the oldest methods of food preservation is by      drying
     Meat, fish and some other foods may be both preserved      and flavored through the use of smoke
     Freezing is also one of the most commonly used      processes commercially and domestically
 Vacuum packing
     Vacuum-packing stores food in a vacuum environment
     Salting or curing draws moisture from the meat through      a process of osmosis.
     Sugar is used to preserve fruits
     Pickling is a method of preserving food in an edible anti-      microbial liquid.
Canning and Bottling
     Canning involves cooking fruits or vegetables, sealing      them in sterile cans or jars
     Food may be preserved by cooking in a material that      solidifies to form a gel.
     Irradiation of food is the exposure of food to
ionizing      radiation    
 Modified atmosphere
     Modified atmosphere
is a way to preserve food by      operating on the atmosphere                             

     Controlled use of microorganism
     Some foods, such as many
cheeses, wines, and beers      will keep for a long time
 High pressure food preservation
     High pressure food preservation refers to
high pressure      used for food preservation.

  vacum packaging