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Infood processing,fermentation is the conversion ofcarbohydrates toalcohol ororganic acids usingmicroorganisms—yeasts orbacteria—without an oxidizing agent being used in the reaction.Fermentation usually implies that the action of microorganisms is desired.[1] The science of fermentation is known aszymology or zymurgy.
The term "fermentation" sometimes refers specifically to the chemical conversion ofsugars intoethanol, producing alcoholic drinks such aswine,beer, andcider. However, similar processes take place in theleavening ofbread (CO2 produced by yeast activity), and in the preservation of sour foods with the production oflactic acid, such as insauerkraut andyogurt.
Other widely consumed fermented foods includevinegar,olives, andcheese. More localized foods prepared by fermentation may also be based on beans, grain, vegetables, fruit, honey, dairy products, and fish.
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.[2] The earliest archaeological evidence of fermentation is 13,000-year-old residues of a beer, with the consistency of gruel, found in a cave nearHaifa in Israel.[3] Another early alcoholic drink, made from fruit, rice, and honey, dates from 7000 to 6600 BC, in theNeolithic Chinese village ofJiahu,[4] and winemaking dates from ca. 6000 BC, inGeorgia, in theCaucasus area.[5] Seven-thousand-year-old jars containing the remains of wine, now on display at the University of Pennsylvania, were excavated in theZagros Mountains inIran.[6] There is strong evidence that people were fermenting alcoholic drinks inBabylon ca. 3000 BC,[7]ancient Egypt ca. 3150 BC,[8] pre-Hispanic Mexico ca. 2000 BC,[7] andSudan ca. 1500 BC.[9]
The French chemistLouis Pasteur foundedzymology, when in 1856 he connected yeast to fermentation.[10]When studying the fermentation of sugar toalcohol byyeast, 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. 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."[11]
Nevertheless, it was known that yeast extracts can ferment sugar even in the absence of living yeastcells. While studying this process in 1897, the German chemist and zymologistEduard Buchner ofHumboldt University of Berlin, Germany, found that sugar was fermented even when there were no living yeast cells in the mixture,[12] by an enzyme complex secreted by yeast that he termedzymase.[13] In 1907 he received theNobel 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 oxidizednicotinamide adenine dinucleotide (NAD+).[14][verification needed]
Food fermentation is the conversion of sugars and othercarbohydrates into alcohol or preservativeorganic acids andcarbon dioxide. All three products have found human uses. The production of alcohol is made use of when fruitjuices are converted towine, when grains are made intobeer, and when foods rich in starch, such aspotatoes, are fermented and then distilled to make spirits such asgin andvodka. The production of carbon dioxide is used toleaven bread. The production of organic acids is exploited to preserve and flavor vegetables and dairy products.[15]
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 throughlactic acid, alcohol,acetic acid, andalkaline[16] fermentations; to enrich food substrates with protein,essential amino acids, and vitamins; to eliminateantinutrients; and to reduce cooking time and the associated use of fuel.[17]
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.[18]
Cheonggukjang,doenjang,douchi,fermented bean curd,miso,natto,soy sauce,stinky tofu,tempeh, oncom, soybean paste, Beijing mung bean milk, kinama,iru, thua nao
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, andchicha, among others.
Kimchi,mixed pickle,sauerkraut,Indian pickle,gundruk,tursu
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Wine,vinegar,cider,perry,brandy,atchara,nata de coco,burong mangga,asinan,pickling,vişinată,chocolate,rakı,aragh sagi,chacha,tempoyak
Some kinds ofcheese also,kefir,kumis (mare milk),shubat (camel milk),ayran,cultured milk products such asquark,filmjölk,crème fraîche,smetana,skyr, andyogurt
Bagoong,faseekh,fish sauce,Garum,Hákarl,jeotgal,ngapi,padaek,pla ra,prahok,rakfisk,shrimp paste,surströmming,shidal
Chorizo,salami,sucuk,pepperoni,nem chua,som moo,saucisson,fermented sausage
Pu-erh tea,Kombucha,Lahpet,Goishicha
Sterilization is an important factor to consider during the fermentation of foods. Failing to completely remove anymicrobes 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 ofbotulism since 1985.[19] It has more cases of botulism than any other state in the United States of America. This is caused by the traditionalAlaska Native practice of allowing animal products such as whole fish, fish heads,walrus,sea lion, andwhale flippers,beaver tails, seal oil, and birds, to ferment for an extended period of time before being consumed. The risk is exacerbated when aplastic container is used for this purpose instead of the old-fashioned, traditional method, a grass-lined hole, as theClostridium botulinum bacteria thrive in the anaerobic conditions created by the air-tight enclosure in plastic.[19]
Research has found that fermented food contains a carcinogenic by-product,ethyl carbamate (urethane).[20] "A 2009 review of the existing studies conducted across Asia concluded that regularly eating pickled vegetables roughly doubles a person's risk foresophageal squamous cell carcinoma."[21]
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Media from Commons
Quotations from Wikiquote
Recipes from Wikibooks
