10.2 Food preservation
Food preservation includes a variety of techniques that allow food to be kept for extended periods of time without losing nutritional quality and avoiding the growth of unwanted microorganisms. There are three basic objectives for the preservation of foods:
- Prevention of contamination of food from damaging agents.
- Delay or prevention of growth of microorganisms in the food.
- Delay of enzymic spoilage, i.e. self-decomposition of the food by naturally occurring enzymes within it.
For storing or preserving food, one or several of the living conditions needed for the growth of microorganisms have to be removed. Like humans, microorganisms need a source of food and water, and they also need a suitable pH and temperature to grow, so food preservation techniques aim to target these requirements. Food preservation depends on procedures which effectively manage the microbial content of foods and on processes that alter or delay the activities of enzymes in the food. The techniques may be applied separately or in combination. Their aims are to prevent contamination in the first place, to remove or reduce the numbers of contaminants, and to prevent microbial growth. We describe them below.