Fermentation in food processing is the process
of converting carbohydrates to alcohol or
organic acids using microorganisms—yeasts
or bacteria—under anaerobic conditions.
Fermentation usually implies that the action
of microorganisms is desired.
The science of fermentation is known as zymology
or zymurgy.
The term fermentation sometimes refers specifically
to the chemical conversion of sugars 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.
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, fish, meat,
or tea.
== History and prehistory ==
Natural fermentation precedes human history.
Since ancient times, humans have exploited
the fermentation process.
The earliest archaeological evidence of fermentation
was 13,000 year old residues of a beer with
the consistency of gruel, 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 Chinese village of Jiahu,
and winemaking dates from 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 c.
3000 BC, ancient Egypt c. 3150 BC, pre-Hispanic
Mexico c. 2000 BC, and Sudan c. 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, not with the death or putrefaction
of the cells", he wrote.
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 NAD+.
== Uses ==
Food fermentation is the conversion of sugars
and other carbohydrates into alcohol or preservative
organic acids and carbon dioxide.
All three products have found human uses.
The production of alcohol is made use of when
fruit juices are converted to wine, when grains
are made into beer, and when foods rich in
starch, such as potatoes, are fermented and
then distilled to make spirits such as gin
and vodka.
The production of carbon dioxide is used to
leaven 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 fermentations; to
enrich food substrates with protein, essential
amino acids, and vitamins; to eliminate antinutrients;
and to reduce cooking time and the associated
use of fuel.
== Fermented foods by region ==
Worldwide: alcohol (beer, wine), vinegar,
olives, yogurt, bread, cheese
Asia
East and Southeast Asia: amazake, atchara,
bai-ming, belacan, burong mangga, com ruou,
dalok, doenjang, douchi, jeruk, lambanog,
kimchi, kombucha, leppet-so, narezushi, miang,
miso, nata de coco, nata de pina, natto, naw-mai-dong,
oncom, pak-siam-dong, paw-tsaynob, prahok,
ruou nep, sake, seokbakji, soju, soy sauce,
stinky tofu, szechwan cabbage, tai-tan tsoi,
chiraki, tape, tempeh, totkal kimchi, yen
tsai, zha cai
Central Asia: kumis (mare milk), kefir, shubat
(camel milk)
South Asia: achar, appam, dosa, dhokla, dahi
(yogurt), idli, kaanji, mixed pickle, ngari,
hawaichaar, jaand (rice beer), sinki, tongba,
paneer
Africa: fermented millet porridge, garri,
hibiscus seed, hot pepper sauce, injera, lamoun
makbouss, laxoox, mageu, mauoloh, msir, mslalla,
oilseed, ogi, ogili, ogiri, iru
Americas: sourdough bread, cultured milk,
chicha, elderberry wine, kombucha, pickling
(pickled vegetables), sauerkraut, lupin seed,
oilseed, chocolate, vanilla, tabasco, tibicos,
pulque, muktuk (fermented bowhead whale)
Middle East: kushuk, lamoun makbouss, mekhalel,
torshi, boza
Europe: rakfisk, sauerkraut, pickled cucumber,
surströmming, mead, elderberry wine, salami,
sucuk, prosciutto, cultured milk products
such as quark, kefir, filmjölk, crème fraîche,
smetana, skyr, rakı, tupí.
Oceania: poi, kaanga pirau (rotten corn),
sago
== 
Fermented foods by type ==
=== 
Bean-based ===
Cheonggukjang, doenjang, fermented bean curd,
miso, natto, soy sauce, stinky tofu, tempeh,
oncom, soybean paste, Beijing mung bean milk,
kinama, iru
=== Grain-based ===
Amazake, beer, bread, choujiu, gamju, injera,
kvass, makgeolli, murri, ogi, rejuvelac, sake,
sikhye, sourdough, sowans, rice wine, malt
whisky, grain whisky, idli, dosa, vodka, boza
=== Vegetable-based ===
Kimchi, mixed pickle, sauerkraut, Indian pickle,
gundruk, tursu
=== Fruit-based ===
Wine, vinegar, cider, perry, brandy, atchara,
nata de coco, burong mangga, asinan, pickling,
vişinată, chocolate, rakı
=== Honey-based ===
Mead, metheglin
=== Dairy-based ===
Some kinds of cheese also, kefir, kumis (mare
milk), shubat (camel milk), cultured milk
products such as quark, filmjölk, crème
fraîche, smetana, skyr, and yogurt
=== Fish-based ===
Bagoong, faseekh, fish sauce, Garum, Hákarl,
jeotgal, rakfisk, shrimp paste, surströmming,
shidal
=== Meat-based ===
Chorizo, salami, sucuk, pepperoni, nem chua,
som moo, saucisson
=== Tea-based ===
Pu-erh tea, Kombucha
== Risks ==
Alaska has witnessed a steady increase of
cases of botulism since 1985.
It has more cases of botulism than any other
state in the United States of America.
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, and birds,
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,
traditional method, a grass-lined hole, as
the Clostridium botulinum bacteria thrive
in the anaerobic conditions created by the
air-tight enclosure in plastic.The World Health
Organization has classified pickled foods
as possibly carcinogenic, based on epidemiological
studies.
Other research found that fermented food contains
a carcinogenic by-product, ethyl carbamate
(urethane).
"A 2009 review of the existing studies conducted
across Asia concluded that regularly eating
pickled vegetables roughly doubles a person's
risk for esophageal squamous cell carcinoma."
== See also
