Fermentation

Fermentation in food procesing typically is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts bacteria, or a combination thereof, under anaerobic conditions. Fermentation in simple terms is the chemical conversion of sugar into ethanol. The science of fermentation is known as  zymurgy.

Fermentation usually implies that the action of microorganisms is desirable, and the process is used to produce alcoholic beverages such as wine, beer and cider. Fermentation is also employed in the leavening of bread, and for preservation techniques to create lactid acid in sour foods such as sauerkraut, dry sausages, kimchi and yoghurt, or vinegar ( acetic acid ) for use in pickling foods.

See also: History of wine and History of beer

Natural 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. 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. There is strong evidence that people were fermenting beverages in Babylon circa 5000 BC, ancient Egypt circa 3150 BC, pre-Hispanic Mexico circa 2000 BC, and Sudan circa 1500 BC. There is also evidence of leavened bread in ancient Egypt circa 1500 BC and of milk fermentation in Babylon circa 3000 BC.

French chemist Louis Pasteur was the first known zymologist, when in 1856 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."