Fermentation in food processing

In food processing, fermentation is a conversion of anaerobic oxygen-free conditions. Fermentation normally implies that the action of microorganisms is desired. The science of fermentation is required as zymology or zymurgy.

The term "fermentation" sometimes allocated specifically to the chemical conversion of sugars into ethanol, producing alcoholic drinks such(a) as wine, beer, as alive as cider. However, similar processes work place in the leavening of bread CO₂ presented by yeast activity, and in the preservation of sour foods with the production of lactic acid, such as in sauerkraut together with yogurt.

Other widely consumed fermented foods include vinegar, olives, and cheese. More localised foods prepared by fermentation may also be based on beans, grain, vegetables, fruit, honey, dairy products, and fish.

History and prehistory

Natural fermentation precedes human history. Since ancient times, humans realize exploited the fermentation process. The earliest archaeological evidence of fermentation is 13,000-year-old residues of a beer, with the consistency of gruel, found in a cave most Haifa in Israel. Another early alcoholic drink, present from fruit, rice, and honey, dates from 7000 to 6600 BC, in the Neolithic Chinese village of Jiahu, and winemaking dates from ca. 6000 BC, in Georgia, in the Caucasus area. Seven-thousand-year-old jars containing the keeps of wine, now on display at the University of Pennsylvania, were excavated in the Zagros Mountains in Iran. There is strong evidence that people were fermenting alcoholic drinks in Babylon ca. 3000 BC, ancient Egypt ca. 3150 BC, pre-Hispanic Mexico ca. 2000 BC, and Sudan ca. 1500 BC.

The French chemist Louis Pasteur founded zymology, when in 1856 he connected yeast to fermentation. When studying the fermentation of sugar to alcohol by yeast, 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, non with the death or putrefaction of the cells", he wrote.

Nevertheless, it was so-called that yeast extracts can ferment sugar even in the absence of living yeast cells. While studying this process in 1897, the German chemist and zymologist Eduard Buchner of Humboldt University of Berlin, Germany, found that sugar was fermented even when there were no living yeast cells in the mixture, by an enzyme complex secreted by yeast that he termed zymase. In 1907 he received the Nobel Prize in Chemistry for his research and discovery of "cell-free fermentation".

One year earlier, in 1906, ethanol fermentation studies led to the early discovery of NAD⁺.