In food processing, fermentation is the conversion of to alcohol or Organic compound acids using — or bacteria—without an oxidizing agent being used in the reaction. Fermentation usually implies that the action of microorganisms is desired.
The term "fermentation" sometimes refers specifically to the chemical conversion of into ethanol, producing alcoholic drinks such as wine, beer, and cider. However, similar processes take place in the leavening of bread (CO2 produced by yeast activity), and in the preservation of sour foods with the production of lactic acid, such as in sauerkraut and yogurt. Humans have an enzyme that gives us an enhanced ability to break down ethanol.
Other widely consumed fermented foods include vinegar, , and cheese. More localized foods prepared by fermentation may also be based on beans, grain, vegetables, fruit, honey, dairy products, and fish.
History and prehistory
Brewing and winemaking
Natural fermentation predates human history. Since ancient times, humans have exploited the fermentation process. They likely began fermenting foods unintentionally. To store excess foods, humans placed the items in a container where they were forgotten. Over time, yeast and bacteria started to grow. This led humans to unveil fermented foods.
The earliest archaeological evidence of fermentation is 13,000-year-old residues of a beer, with the consistency of gruel, found in a cave near
Haifa in Israel.
Another early alcoholic drink, made from fruit, rice, and honey, dates from 7000 to 6600 BC, in the
Neolithic China village of
Jiahu,
and winemaking dates from ca. 6000 BC, in Georgia, in the
Caucasus area.
Seven-thousand-year-old jars containing the remains 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,
ca. 3150 BC,
pre-Hispanic Mexico ca. 2000 BC,
and
Sudan ca. 1500 BC.
Discovery of the role of yeast
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 "
Vitalism", within the yeast cells. The "ferments" were thought to function only within living organisms. Pasteur wrote that "Alcoholic fermentation is an act correlated with the life and organization of the yeast cells, not with the death or putrefaction of the cells."
"Cell-free fermentation"
Nevertheless, it was known 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 oxidized nicotinamide adenine dinucleotide (NAD+).
Uses
Food fermentation is the conversion of sugars and other
into alcohol or preservative
and
carbon dioxide. All three products have found human uses. The production of alcohol is made use of when fruit
are converted to
wine, when grains are made into
beer, and when foods rich in starch, such as
, are fermented and then distilled to make spirits such as
gin and
vodka. The production of carbon dioxide is used to
leavening agent bread. The production of organic acids is exploited to preserve and flavor vegetables and dairy products.
Food fermentation serves five main purposes: to enrich the diet through development of a diversity of flavors, aromas, and textures in food substrates; to preserve substantial amounts of food through lactic acid, alcohol, acetic acid, and alkaline
Beverages produced through fermentation have likely universally been associated with ceremonies and festivals. There is some understanding of how they have been consumed in such contexts, derived from the construction of drinkware, and residue contained therein.
Fermented foods by region
-
Worldwide: alcohol (beer, wine), vinegar, , yogurt, bread, cheese
-
Asia
-
East and Southeast Asia: amazake, atchara, belacan, burong mangga, com ruou, doenjang, douchi, fish sauce, Lahpet, Arrack, kimchi, kombucha, leppet-so, narezushi, miso, nata de coco, nattō, ngapi, oncom, padaek, pla ra, prahok, ruou nep, sake, shrimp paste, soju, soy sauce, stinky tofu, tape, tempeh, tempoyak, zha cai
-
Central Asia: kumis, kefir, shubat, qatiq (yogurt)
-
South Asia: achar, appam, dosa, dhokla, Yogurt (yogurt), idli, mixed pickle, ngari, sinki, tongba, paneer
-
Africa: garri, injera, laxoox, mageu, ogi, ogiri, iru
-
Americas: chicha, chocolate, vanilla, hot sauce, tepache, tibicos, pulque, muktuk, kiviak, parakari
-
Middle East: torshi, boza
-
Europe: sourdough bread, elderberry wine, kombucha, pickling, rakfisk, sauerkraut, pickled cucumber, surströmming, mead, kvass, salami, sucuk, prosciutto, cultured milk products such as quark, kefir, filmjölk, crème fraîche, smetana, skyr, rakı, tupí, żur.
-
Oceania: poi, kānga pirau
Fermented foods by type
Beans
Cheonggukjang,
doenjang, fermented bean curd,
miso,
natto,
soy sauce,
stinky tofu,
tempeh, oncom, soybean paste, Beijing mung bean milk, kinama, iru, thua nao
Grain
Amazake,
beer,
bread,
choujiu,
gamju,
injera,
kvass,
makgeolli, murri, ogi,
rejuvelac,
sake,
sikhye,
sourdough,
sowans,
rice wine,
malt whisky,
grain whisky,
idli, dosa, Bangla (drink)
vodka,
boza, and
chicha, among others.
Vegetables
Kimchi,
mixed pickle,
sauerkraut,
Indian pickle,
gundruk,
tursu
Fruit
Wine,
vinegar,
cider,
perry,
brandy,
atchara, nata de coco,
burong mangga,
asinan,
pickling, vişinată,
chocolate, rakı,
aragh sagi, chacha,
tempoyak
Honey
Mead,
metheglin,
tej
Dairy
Some kinds of
cheese also,
kefir,
kumis (mare milk),
shubat (camel milk),
ayran, cultured milk products such as quark, filmjölk, crème fraîche, smetana,
skyr, and
yogurt
Fish
Bagoong,
faseekh,
fish sauce,
Garum, Hákarl,
jeotgal,
ngapi,
padaek,
pla ra,
prahok,
rakfisk,
shrimp paste, surströmming,
shidal
Meat
Chorizo,
salami,
sucuk,
pepperoni,
nem chua chua,
som moo,
saucisson, fermented sausage
Tea
Pu-erh tea,
Kombucha,
Lahpet,
Goishicha
Risks
Sterilization is an important factor to consider during the fermentation of foods. Failing to completely remove any
microbes from equipment and storing vessels may result in the multiplication of harmful organisms within the ferment, potentially increasing the risks of food borne illnesses such as botulism. However, botulism in vegetable ferments is only possible when not properly canned. The production of off smells and discoloration may be indications that harmful bacteria may have been introduced to the food.
Alaska has witnessed a steady increase of cases of botulism since 1985.
Research has found that fermented food contains a carcinogenic by-product, ethyl carbamate (urethane).
See also
External links
