The basic principles of food preservation primary involves the process of inhibiting
- The growth and activity of microorganism
- Activity of endogenous enzymes
- Chemical reactions which may deteriorate the quality of food
- Invasion and spoilage by insects and rodents
In addition, spoilage of food may be caused during mechanical handling, processing, packaging, storing and transportation. Appropriate care has to be exercised to prevent deterioration of quality of food.
Several methods are available for preservation of food based on the above principles, the method include:
- Preventing the accessibility of food to microorganism by asepsis and packaging
- Physical removal of microorganisms from food by filtration or centrifugation
- Hindering the growth and activity of microorganism by use of preservatives, use of low temperatures atmospheric control in packaging and storing of foods and decreasing water activity in foods by drying or evaporation
- Killing the microorganism by use of high temperature and ionizing radiation
- Inactivation of endogenous enzymes by moderate heating
- Inhibition of chemical reaction through the use of chemical additives
- Fermentation of foods to yield more stable or less perishable food product
Food preservation as it is practiced in the industry always involves the use of combination of methods for achieving maximum effectiveness.
Asepsis or preventing the accessibility of food to microorganisms is well exemplified in nature, the protective covering in natural foods such as skins on fruits and vegetables, shells on eggs and nuts and skins and membranes on livestock and fish prevent the attack by microorganisms and maintain the living tissues in healthy condition.
Microbial attack is facilitated only after the death of the animal or when the skin is physically damaged. Packaging of foods and food products in a variety of materials such as metal cans, plastic films pouches, bags or boxes, paper bags or cartons and glass bottles provide effective protection against microbial attack.
Filtration or centrifugation is adopted to physically remove microorganisms particularly in liquid foods such as milk, soft drinks, fruits juices and alcoholic beverages such as wine and beer.
Principle of Food Preservation