Food preservation

  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)