Fermentation in
food processing typically is the conversion of
carbohydrates to
alcohols and carbon dioxide or organic acids using
yeasts,
bacteria, or a combination thereof, under
anaerobic conditions. A more restricted definition of fermentation is the chemical conversion of
sugars into
ethanol. The science of fermentation is known as
zymology.
Fermentation usually implies that the action of the microorganisms is desirable, and the process is used to produce alcoholic beverages such as wine, beer, and cider. Fermentation is also employed in preservation techniques to create lactic acid in sour foods such as saurkraut, dry sausages, kimchi and yogurt, or vinegar (acetic acid) for use in pickling foods.
Since fruits ferment naturally, fermentation precedes human history. Since ancient times, however, humans have been controlling the fermentation process. The earliest evidence of winemaking dates from eight thousand years ago, in Georgia, in the Caucasus area.[1] Seven-thousand-year-old jars containing the remains 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.
When studying the fermentation of sugar to alcohol by yeast, Louis Pasteur concluded that the fermentation was catalyzed by a vital force, called "ferments," within the yeast cells. The "ferments" were thought to function only within living organisms. "Alcoholic fermentation is an act correlated with the life and organization of the yeast cells, not with the death or putrefaction of the cells,"[7] he wrote.
