Canning & Preserving

Food preservation is the process of treating and handling food in such a way as to stop or greatly slow down spoilage to prevent foodborne illness while maintaining nutritional value, texture and flavor. more...

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Preservation Processes

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 aging and discolouration that can occur during food preparation such as the polyphenoloxidase 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; others, such as drying, allow food to be stored without any special containment for long periods.

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)
• Many combinations of these methods
• Chelation

Methods

Common methods of applying these processes include drying, freeze drying, freezing, vacuum-packing, canning, preserving in syrup, sugar crystalisation, 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 crystalisation and curing.

Drying

One of the oldest methods of food preservation is by drying, which reduces water activity sufficient to delay or prevent bacterial growth. Most types of meat can be dried. This is especially valuable in the case of pig meat, since it is difficult to keep without preservation. Many fruits can also be dried; for example, the process is often applied to apples, pears, bananas, mangos, papaya, and coconut. Zante Currants, sultanas and raisins are all forms of dried Grapes. Drying is also the normal means of preservation for cereal grains such as wheat, maize, oats, barley, rice, millet and rye.

Freezing

Freezing is also one of the most commonly used processes commercially and domestically for preserving a very wide range of food stuffs including prepared food stuffs which would not have required freezing in their unprepared state. For example, potato waffles are stored in the freezer, but potatoes themselves require only a cool dark place to ensure many months' storage.

Cold stores provide large volume, long-term storage for strategic food stocks held in case of national emergency in many countries.

Vacuum Packing

Vacuum-packing stores food in a vacuum environment, usually in an air-tight bag or bottle. The vacuum environment strips bacteria of oxygen needed for survival, hence preventing the food from spoiling. Vacuum-packing is commonly used for storing nuts.

Read more at Wikipedia.org