Fermentation is an anaerobic process in which energy can be released from glucose even if oxygen is not available. In food production, it may more broadly refer to any process in which the activity of microorganisms brings about a desirable change to a foodstuff or beverage. The science of fermentation is known as zymology. It is used for preservation in a process that produces lactic acid found in such sour foods as pickled cucumbers, kombucha, kimchi, and yogurt, as well as for producing alcoholic beverages such as wine and beer. It also occurs within the gastrointestinal tracts of all animals, including humans.
Process of Fermentation
It is an anaerobic biochemical process. The first process is the same as cellular respiration, which is the formation of pyruvic acid by glycolysis where net 2 ATP molecules are synthesized. In the next step, pyruvate is reduced to lactic acid, ethanol, or other products. Here NAD+ is formed which is re-utilized back in the glycolysis process.
Types of Fermentation
- Lactic Acid Fermentation: In this, starch or sugar is converted into lactic acid by yeast strains and bacteria. During exercise, energy expenditure is faster than the oxygen supplied to the muscle cells. This results in the formation of lactic acid and painful muscles.
- Alcohol Fermentation: Pyruvate, the end product of glycolysis is broken down into alcohol and carbon dioxide. Wine and beer are produced by alcoholic fermentation.
- Acetic Acid Fermentation: Starch and sugar present in grains and fruits ferment into vinegar and condiments. E.g. apple cider vinegar.
It has many health benefits and is used in the production of alcoholic beverages, bread, yogurt, sauerkraut, apple cider vinegar, and kombucha. It is also used in industry to generate ethanol as a source of biofuel.