Food preservation is a group of techniques that are used to prolong shelf life and slow rotting of food items. Many variables contribute to food spoilage. These include but not limited to; microorganisms such as bacteria, fungus and mold, air and light which contribute to the oxidation of fats. The importance of food preservation is keeping foods safer and for longer periods of storage.
Some food items may require several food preservation methods before getting to the preserved food product.
Types of Food Preservation
Drying can be performed by all natural methods by which the food item is spread out in single layer to dry in the sun. The natural method requires certain weather characteristics that are only available in hotter climates. The method preferred by home gardeners and cooks is through the use of food dehydrators which run warm air over the item to evaporate the moisture out of the item.
Refrigeration is one method of food preservation that uses air temperatures which are set low to slow the growth of microorganisms.
Freezing is used mostly to preserve prepared food items. Freezing requires that the moisture in the item be brought to below 32 degrees Fahrenheit.
Vacuum packing takes the air out of a food item that is contained in a plastic bag or other type of container. Vacuum packing reduces oxidation and is commonly combined with freezing.
Salt curing has been used as a food preservation technique for thousands of years. Meats are usually salted for preservation. The salt acts as a food preservative and pulls most of the moisture out of the meat creating an environment that does not promote bacteria growth. Food preserving can extend the shelf life of a meat item for years. Beef jerky is a good example of salt preserved meat. Salt is used to make green bacon which is salt cured but not smoked.
Sugar is used mainly to preserve fruit and can be introduced in either syrup or by candying or boiling fruit skins in sugar until crystallization forms.
Pickling involves cooking and storing the food item in an anti-microbial liquid such as a brine, alcohol, vinegar or oils.
Using lye in food preservation is rare but does exist in some cultures. The lye creates an environment too alkaline for any microorganisms to grow. Lutefisk is a Norwegian dish that uses lye to preserve fish.
Canning and Bottling
Canning cooks the food and seals it in sterilized jars or cans and then the contents are boiled to kill and microbes. Canning is a common form of preservation for the home cook.
Cooking food until it turns to a gel such as fruit jellies.
Potting involves putting the food item (meat or seafood, potted shrimp) and adding a layer of fat to seal the container.
This is a commercial process that exposes food to radiation ions that kill all types of microorganisms.
Artificial food additives
Sometimes chemicals are added as food preservatives to help preserve food. These can be found on many labels of common food items and are used often in commercial food production.