Fermentation in food processing is the conversion
of carbohydrates to alcohols and carbon dioxide
or organic acids using yeasts, bacteria, or
a combination thereof, under anaerobic conditions.
Fermentation usually implies that the action
of microorganisms is desirable.
The science of fermentation is also known
as zymology or zymurgy.
The term "fermentation" is sometimes used
to specifically refer to the chemical conversion
of sugars into ethanol, a process which is
used to produce alcoholic beverages such as
wine, beer, and cider.
Fermentation is also employed in the leavening
of bread; in preservation techniques to produce
lactic acid in sour foods such as sauerkraut,
dry sausages, kimchi, and yogurt; and in pickling
of foods with vinegar.
Natural fermentation precedes human history.
Since ancient times, however, humans have
been controlling the fermentation process.
The earliest evidence of an alcoholic beverage,
made from fruit, rice, and honey, dates from
7000–6600 BCE, in the Neolithic Chinese
village of Jiahu, and winemaking dates from
6000 BCE, 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 beverages in Babylon circa 3000
BC, ancient Egypt circa 3150 BC, pre-Hispanic
Mexico circa 2000 BC, and Sudan circa 1500
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.
Contributions to biochemistry
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," 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, 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 a yeast secretion that he termed
zymase.
In 1907 he received the Nobel Prize in Chemistry
for his research and discovery of "cell-free
fermentation."
One year prior, in 1906, ethanol fermentation
studies led to the early discovery of NAD+.
Uses
The primary benefit of fermentation is the
conversion of sugars and other carbohydrates
into preservative organic acids, e.g. converting
juice into wine, grains into beer, carbohydrates
into carbon dioxide to leaven bread, and sugars
in vegetables.
Food fermentation has been said to serve five
main purposes:
Enrichment of the diet through development
of a diversity of flavors, aromas, and textures
in food substrates
Preservation of substantial amounts of food
through lactic acid, alcohol, acetic acid,
and alkaline fermentations
Biological enrichment of food substrates with
protein, essential amino acids, and vitamins
Elimination of antinutrients
A decrease in cooking time and fuel requirement
Fermented foods by region
Worldwide: alcohol, 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, kefir, shubat
South Asia: achar, appam, dosa, dhokla, dahi,
idli, kaanji, mixed pickle, ngari, hawaichaar,
jaand, sinki, tongba, paneer
Africa: fermented millet porridge, garri,
hibiscus seed, hot pepper sauce, injera, lamoun
makbouss, laxoox, mauoloh, msir, mslalla,
oilseed, ogi, ogili, ogiri, iru
Americas: sourdough bread, cultured milk,
chicha, elderberry wine, kombucha, pickling,
sauerkraut, lupin seed, oilseed, chocolate,
vanilla, tabasco, tibicos, pulque, mikyuk
Middle East: kushuk, lamoun makbouss, mekhalel,
torshi, boza
Europe: rakfisk, sauerkraut, pickled cucumber,
surströmming, mead, elderberry wine, salami,
prosciutto, cultured milk products such as
quark, kefir, filmjölk, crème fraîche,
smetana, skyr.
Oceania: poi, kaanga pirau, sago
Fermented foods by type
Bean-based
Cheonggukjang, doenjang, miso, natto, soy
sauce, stinky tofu, tempeh, soybean paste,
Beijing mung bean milk, kinama, iru
Grain-based
Amazake, beer, bread, choujiu, gamju, injera,
kvass, makgeolli, murri, ogi, sake, sikhye,
sourdough, sowans, rice wine, malt whisky,
grain whisky, idli, dosa, vodka
Vegetable based
Kimchi, mixed pickle, sauerkraut, Indian pickle,
gundruk
Fruit based
Wine, vinegar, cider, perry, brandy, atchara,
nata de coco, burong mangga, asinan, pickling,
vişinată
Honey based
Mead, metheglin
Dairy based
Cheese, kefir, kumis, shubat, cultured milk
products such as quark, filmjölk, crème
fraîche, smetana, skyr, yogurt
Fish based
Bagoong, faseekh, fish sauce, Garum, Hákarl,
jeotgal, rakfisk, shrimp paste, surströmming,
shidal
Meat based
Jamón ibérico, Chorizo, Salami, Pepperoni,
Nem chua, Som moo
Tea based
Pu-erh tea, Kombucha
Risks of consuming fermented foods
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, birds, etc.,
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 botulinum bacteria thrive in the anaerobic
conditions created by the air-tight enclosure
in plastic.
The World Health Organization has classified
pickled foods as a possible carcinogen, based
on epidemiological studies.
Other research found that fermented food contains
a carcinogenic by-product, ethyl carbamate.
"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
References
External links
Fermentations in world food processing
Fermentations in world food processing
Science aid: Fermentation - Process and uses
of fermentation
Fermented cereals.
A global perspective - FAO 1999
