Most spoilage of food meant for human consumption is caused by microorganisms, which effectively compete with humans for limited and valuable food resources. Spoiled foods may be safe to eat, i.e. they may not cause illness because there are no pathogens or a toxin present, but changes in texture, smell, taste, or appearance cause them to be rejected.
In principle spoilage prevention may be achieved in the
following ways:
• by keeping out or removing microorganisms,
• by hindering growth and activity of microorganisms, and
• by killing microorganisms.
The development of food preservation processes has been driven by the need to extend the shelf-life of foods. Food preservation is a continuous fight against microorganisms spoiling the food or making it unsafe. Several food preservation systems such as heating, refrigeration and addition of antimicrobial compounds can be used to reduce the risk of outbreaks of food poisoning.
Low temperatures are used to retard chemical reactions and action of food enzymes and to slow or stop growth and activity of microorganisms. Temperatures that are just above freezing maintain foods near their original condition without special pretreatments. Storage time in such a case is limited, because some bacteria, yeasts and molds can grow at low temperatures, although this growth is much slower than at higher temperatures.
Increased temperatures can have a more permanent preservative, effect, and only require a fairly brief treatment. They may also alter the flavor of food.
Through millennia of observation and experimentation and depending on geographic location and cultural history, humans developed many methods to extend the shelf life of common foodstuffs. They learned how to manipulate osmotic conditions through the addition of sugars, salts, or lipids (e.g., sugar for jams, jellies, and syrups; salt for fish and meat; oil or fat from olives and butter) to inhibit deleterious microbial growth.
Growth of microorganisms and their activity may also be hindered by chemical agents known to specialists as preservatives. Chemical preservatives are substances which are added to food just to retard, inhibit or arrest the activity of microorganisms such as fermentation, putrefaction and decomposition of the food. Commonly used preservatives include, common salt, sugar, dextrose, spices, vinegar, ascorbic acid, benzoic acid and its salt, SO2 and the salts of sulphuric acid, nitrates, sorbic acid and its salts, propionic acid and its salts, lactic acid and its salts.
Many herbs, essential oils, and spices have demonstrated some inhibitory activity against spoilage microbes in a variety of foods. Thyme, oregano, vanillin, and cinnamon are the most commonly used.
Formulation of processed foods may include compounds that alter the water activity or pH of foods, thereby limiting growth of many organisms.
Preserving food can help to avoid wasting of food. Food preservation involves preventing the food from being spoilt. Preservation of food is the process by which food is stored by special methods.
Prevention of spoilage in food
