Fermented foods are staples of the human diet and usually have an improved microbial stability and safety. In addition, some can be stored even at ambient temperatures. Furthermore, there are several examples of fermentation processes which lead to an increase in nutritional value or digestibility.
Fermentation happens commonly in yeast and bacteria and also in oxygen-starved muscle cells, as in the case of lactic acid fermentation. Microorganisms are integral part of the processing system during the production of fermented foods. In terms of microbiologists, fermentation is a primary means of producing ATP by the degradation of organic nutrients anaerobically, in presence of suitable microorganisms.
Science of fermentation is called zymology. Research shows that fermentation processes have been developed in order to preserve foods for times of scarcity by preserving the food by organic acid and alcohols at the same time it imparts desirable flavor, texture to foods, reduce toxicity and decrease cooking time.
Fermentation is employed in the production of foods and its major roles including:
(1) Preservation of food through formation of inhibitory metabolites such as organic acid;
(2) improving food safety through inhibition of pathogens or removal of toxic compounds;
(3) improving the nutritional value and also makes the food palatable by enhancing its aroma and flavor.
Food preservation: Fermentation 
