Fermentation typically refers to the conversion of sugar to alcohol using yeast under anaerobic conditions. A more general definition of fermentation is the chemical conversion of carbohydrates into alcohols or acids. When fermentation stops prior to complete conversion of sugar to alcohol, a stuck fermentation is said to have occurred. The science of fermentation is known as zymology.
Since fruits ferment naturally, fermentation precedes human history. Since prehistoric times, however, humans have been taking control of the fermentation process. The earliest evidence of dates of winemaking from 6000 BC, in Georgia, the former Soviet Republic.[1] 7000 year old jars of wine have been excavated in the Zagros Mountains in Iran, which are now on display at the University of Pennsylvania.[2] There is strong evidence that people were fermenting beverages in Babylon circa 5000 BC,[3]ancient Egypt circa 3150 BC,[4] pre-Hispanic Mexico circa 2000 BC,[3] and Sudan circa 1500 BC.[5] There is also evidence of leavened bread in ancient Egypt circa 1500 BC[6] and of milk fermentation in Babylon circa 3000 BC.[3] The Chinese were probably the first to develop vegetable fermentation.[3]
French chemist Louis Pasteur was the first zymologist, when in 1857 he connected yeast to fermentation. Pasteur originally defined fermentation as "respiration without air". Pasteur performed careful research and concluded;
"I am of the opinion that alcoholic fermentation never occurs without simultaneous organization, development and multiplication of cells.... If asked, in what consists the chemical act whereby the sugar is decomposed ... I am completely ignorant of it."
The GermanEduard Buchner, winner of the 1907Nobel Prize in chemistry, later determined that fermentation was actually caused by a yeast secretion that he termed zymase.[7]
Uses
The primary benefit of fermentation is the conversion of sugars and other carbohydrates, e.g., converting juice into wine, grains into beer, carbohydrates into carbon dioxide to leaven bread, and sugars in vegetables into preservative organic acids.
Food fermentation has been said to serve five main purposes:[8]
Enrichment of the diet through development of a diversity of flavors, aromas, and textures in food substrates.
Biological enrichment of food substrates with protein, essential amino acids, essential fatty acids, and vitamins.
Detoxification during food-fermentation processing.
A decrease in cooking times and fuel requirements.
Fermentation has some uses exclusive to foods. Fermentation can produce important nutrients or eliminate antinutrients. Food can be preserved by fermentation, since fermentation uses up food energy and can make conditions unsuitable for undesirable microorganisms. For example, in pickling the acid produced by the dominant bacteria inhibit the growth of all other microorganisms. Depending on the type of fermentation, some products (e.g., fusel alcohol) can be harmful to people's health.
Alaska, despite its small population, has witnessed a steady increase of cases of botulism since 1985. It has more cases of botulism than any other state.[9] This is caused by the traditional Eskimo practice of allowing animal products such as whole fish, fish heads, walrus, sea lion and whale flippers, beaver tails, seal oil, birds, etc., to ferment for an extended period of time before being consumed. The risk is exacerbated when a plastic container is used for this purpose instead of the old-fashioned method, a grass-lined hole, as the botulinum bacteria thrive in the anaerobic conditions created by the plastic.
^ Dirar, H., (1993), The Indigenous Fermented Foods of the Sudan: A Study in African Food and Nutrition, CAB International, UK
^ Sugihara, T.F., (1985), Microbiology of Breadmaking, in "."Microbiology of Fermented Foods", edited by Wood, B.J.B., Elsevier Applied Science Publishers, UK
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