fermentation

1. 1. The anaerobic conversion of sugar to carbon dioxide and alcohol by yeast.
   2. Any of a group of chemical reactions induced by living or nonliving ferments that split complex organic compounds into relatively simple substances.
2. Unrest; agitation.

Decomposition of foodstuffs generally accompanied by the evolution of gas. The best-known example is alcoholic fermentation, in which sugar is converted into alcohol and carbon dioxide. During fermentation organic matter is decomposed in the absence of air (oxygen); hence, there is always an accumulation of reduction products, or incomplete oxidation products. Some of these products (for example, alcohol and lactic acid) are of importance to humans, and fermentation has therefore been used for their manufacture on an industrial scale. There are also many microbiological processes that go on in the presence of air while yielding incomplete oxidation products. Good examples are the formation of acetic acid (vinegar) from alcohol by vinegar bacteria, and of citric acid from sugar by certain molds (for example, Aspergillus niger). These microbial processes, too, have gained industrial importance, and are often referred to as fermentations, even though they do not conform to L. Pasteur's concept of fermentation as a decomposition in the absence of air. See also Industrial microbiology.

Anaerobic metabolism. Used generally of alcohol fermentation of sugars, also production of lactic acid, citric acid, etc., by micro-organisms, which may be yeasts, bacteria or fungi.

The breakdown of organic substances by organisms to release energy in the absence of oxygen. It is especially applied to the anaerobic breakdown of carbohydrates by yeasts to produce alcohol and carbon dioxide, and the bacterial breakdown of milk sugar to give lactic acid (as in the production of cheese and yoghurt). See also colonic fermentation.

A process by which food or drink goes through a chemical change caused by enzymes produced from bacteria, microorganisms or yeasts. Fermentation alters the appearance and/or flavor of foods and beverages such as beer, buttermilk, cheese, vinegar, yogurt, liquor and wine. In wine, for example, yeast enzymes convert grape-juice sugars into alcohol while in rum, the enzymes convert sugar cane molasses into alcohol. With whiskeys, a mash is made from cereal grains such as corn, rye or barley-diastase enzymes convert the grain's starches into sugar, which is subsequently converted by yeast to alcohol.

A chemical change that is brought about in a substance by the action of an enzyme or microorganism, especially the anaerobic conversion of foodstuffs to certain products such as acetic fermentation, alcoholic fermentation.

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Scientists have theorized that fermentation was the process through which energy was first harvested from organic compounds. Fermentation evolved before Earth's atmosphere contained free oxygen. Aerobic respiration differs from fermentation in that the products of glycolysis enter the Krebs cycle rather than being used to form lactic acid or alcohol. Fermentation must have predated the appearance of oxygen in the atmosphere, which occurred over 2.5 billion years ago. Fermentation is thus an ancient process and occurs normally in microorganisms that live in the absence of oxygen.

Fermentation is one of the oldest known food preservation techniques. Along with drying and salting, fermentation was a key method of extending the life of foods, allowing them to be available, and eaten safely, in times of scarcity or seasonal nonavailability. These methods helped allow the transition from hunting and gathering to organized food cultivation and storage, which took place some ten to fifteen thousand years ago in the Middle East.

Fermentation involves the action of desirable microorganisms, or their enzymes, on food ingredients to make biochemical changes, which cause significant modification to the food. Often lactic-acid bacteria convert the carbohydrate energy source of food, such as lactose in milk, to lactic acid; examples are yogurt and cheeses from milk, and pickles from fruits and vegetables. Alternatively, yeasts, often of the Saccharomyces species, may convert the glucose to ethanol and carbon dioxide in leavened breads, or the sugars in grain or fruit beverages to beers and wines. Molds also can be active in certain fermentations, such as Stilton cheese and soy sauce. It is estimated that about one-third of all the food we consume is fermented. World estimates for beer consumption are about 22 million gallons, and a total of 15 million tons of some one thousand varieties of cheese are eaten annually.

Fermented Beverages and Foods

Fermentation is often the key to the safe, enjoyable consumption of perishable food materials, as it changes their composition, flavor, and texture. For example, milk is a nutritious but highly perishable beverage. Originally, in the Middle East, milk carried in animal-skin containers, often on horseback, would sour naturally, to produce acidic fermented milk. The combined action of the two lactic-acid bacteria, Streptococcus lactis, producing lactic acid, and Lactobacillus bulgaricus, producing lactic acid and acetaldehyde, a major contributor to flavor, are involved in yogurt production. The Tartars of Central Asia used the milk of horses, donkeys, or camels to produce a fizzy, gray acidic and alcoholic drink, kumiss, in which yeasts were active.

In acid conditions, the milk protein, casein, denatures and is precipitated to form a curd, producing cottage and soft cheese. By stirring and pressing, whey is removed and a more solid curd is produced, which by ripening or maturation produces semi-hard or hard cheeses. Surface-active bacteria of Brevibacterium linens are active in producing the aroma of Limburger type cheeses, while the blue molds of the genus Penicillium give Stilton and Gorgonzola cheeses their character.

The use of Saccharomyces yeasts has allowed the production of a range of fermented beverages, enabling safe consumption of liquid when fresh water supplies are not available. Lagers, the light golden, gassy beverage made by "bottom" yeast fermentation of cereal extracts, were first made in the regions of Germany and Czechoslovakia, but are now produced and consumed throughout the world. In Africa, a thick, sour alcoholic beverage is made from sorghum or millet, or sometimes maize or banana. These sorghum beers are important sources of nutrients, particularly B vitamins, to people on marginal diets in these regions. The Romans planted extensive vineyards in North Africa to harvest and ferment their grapes into wine, thereby producing a fermented beverage that could be readily stored, transported, and consumed when and where required.

Distillation of these alcoholic beverages, such as whiskey from beers, brandies from grape wines, or arrack from palm or rice wine, further extend our range of drinks and play important cultural roles in festivities.

Fermentation Vessels and Starter Cultures

Art meets science in the production of fermented foods. Traditional practices are passed down through generations of producers, often small in scale, and consumption patterns often have great cultural importance. In Scandinavia, traditionally the brides and mothers jealously guard their own supplies of sourdough starters, so that they can always make the desired bread for their partners and families. In West Africa, a homeowner keeps a supply of dawadawa, a dried fermented African locust bean paste (Parkia species); it is used to give everyday soups and stews the desired "meaty" flavor, while also providing important nutrients, such as riboflavin, the B vitamin that protects against blindness, which is endemic to the region due to nutritional deficiency.

In Korea, few meals are complete without kimchi, a pickled fermented cabbage, which may also contain fish and other components. The practice of every home having their own kimchi jars, often on their verandahs, originated as a way of preserving vegetables through the cold winter season, providing year-round vitamin C. Kimchi together with kochujang, the fermented red pepper paste, give Korean preparations a unique and characteristic attractive color and flavor.

Where food fermentation occurred naturally as conditions favored particular organisms, an important art arose to encourage the desired fermentation organisms, while preventing undesirable microorganisms from developing, for successful fermented food production.

Food storage often took place in earthenware vessels, whose semipermeable inner walls were difficult to clean completely. This allowed a biofilm of desirable microorganisms to remain, to initiate a successful fermentation of the next batch of food. Because of their significance, the vessels themselves were artistically designed and treasured. Interesting examples can be seen in museum collections, such as the Nezu Museum in Tokyo, Japan, and a museum dedicated to kimchi in Seoul, South Korea.

In Europe, the fermented meat producers, while using ceramic or metallic vats with smoother, more easily cleaned surfaces, developed the technique of "backslopping" to introduce a small quantity of the fermenting liquor from the previous batch of meat to initiate successful fermentation.

In many cases, dried grains or balls of the derived fermenting microorganisms on cereal or other substrates would be used to start fermentation. Baker's yeast may be used in this work. Kefir grains are used in North Africa, the Middle East, and Russia for production of kefir, laban, or leben fermented milks. Ragi is used in Indonesia and throughout East and Southeast Asia as inoculum for lao-chao and other fermented foods.

Cultural Diversity

The production, consumption, and enjoyment of different fermented foods reflects the diversity of cultures and cuisines that make up our varied world. In Chinese and Japanese cuisines, shoyu, or soy sauce, is added almost universally to dishes, while the Indian vegetarian diet depends on fermented cereals and legumes, often in combinations, as in dosas and vadas. The art and science of fermenting meat to a wide range of salamis are vital to the enjoyment of Eastern and Central Europeans, while Italian food market stall holders proudly display their mold-covered fermented sausages and traditional cheeses.

As people migrate, they normally carry their traditional fermented food practices with them. The range of fermented cheeses and meats in Latin America reflects the European origins of these populations, and the wineries of Chile were originally established by French families. Consumers of imported wine, chocolate, coffee, or tea are all beneficiaries of the internationalism and significance of fermented foods.

Bibliography

Campbell-Platt, Geoffrey. Fermented Foods of the World: A Dictionary and Guide. London: Butterworth, 1987

Steinkraus, Keith, ed. Handbook of Indigenous Fermented Foods. 2nd ed. NewYork: Marcel Dekker, 1995.

Wood, Brian J. B., ed. Microbiology of Fermented Foods. 2nd ed. London: Blackie, 1998.

—Geoffrey Campbell-Platt

[fer-men-TAY-shuhn] The natural process that turns grape juice into wine, fermentation is actually a chain reaction of chemical responses. During this process, technically called the primary fermentation, the sugars in the grape juice are converted by the enzymes in yeasts into alcohol (55 to 60 percent) and carbon dioxide (40 to 45 percent). In addition, fermentation generates minor amounts of numerous incidental by-products that affect the aroma and taste of wine including acetaldehyde, acetic acid (see acids), ethyl acetate, glycerol and alcohols other than ethanol. One of the potential problems winemakers must avoid is a stuck fermentation. This occurs when the yeast stops converting the sugar into alcohol and carbon dioxide, thereby prematurely leaving undesirable residual sugar in the wine. As more is learned about fermentation, techniques are evolving to manage the process in order to produce optimum wines. For example, managing the temperature during the fermentation-cooler temperatures (45 to 60°F) for white wines, warmer temperatures (70 to 85°F) for heavier red wines-leads to superior wines. Red wines are usually fermented with their skins, seeds, and pulp to extract color and tannins-something not desirable in white wines. yeast strains are also being experimented with to determine which ones work best for different wines under various conditions. Many winemakers believe barrel fermentation adds flavor and complexity to some white wines. carbonic maceration is a specialized fermentation process for producing light fruity red wines. See also bottle fermentation; fermentation containers; malolactic fermentation; secondary fermentation; whole berry fermentation.

A chemical reaction in which sugars are broken down into smaller molecules that can be used in living systems. Alcoholic beverages, such as beer, wine, and whiskey, are made from the controlled use of fermentation. Fermentation is an anaerobic process.

The anaerobic enzymatic conversion of organic compounds, especially carbohydrates, to simpler compounds, especially to lactic acid or ethyl alcohol, producing energy in the form of ATP. An essential part of the digestion that goes on in the rumen and in the colon and cecum of horses. Used commercially in the preparation of alcoholic beverages and the generation of by-products used as animal feed. Also the basic process in the manufacture of antibiotics.

• batch f. — one of the methods used in the industrial production of microorganisms, where the sterile growth medium is inoculated with the microorganisms and no additional growth medium is added.

Look up fermentation in Wiktionary, the free dictionary.

Fermentation may refer to: the or

• Fermentation (biochemistry), the process of energy production in a cell under anaerobic conditions (without oxygen)
• Ethanol fermentation, a form of anaerobic respiration used primarily by yeasts when oxygen is not present in sufficient quantity for normal cellular respiration
• Fermentative hydrogen production
• Industrial fermentation, the breakdown and re-assembly of biochemicals for industry, often in aerobic growth conditions

In food science, fermentation may refer to:

• Fermentation (food), the conversion of carbohydrates into alcohols or acids under anaerobic conditions used for making certain foods
• Fermentation (wine), the process of fermentation commonly used in winemaking.
• Fermentation (beer), the process of fermentation commonly used in brewing beer.
• Fermentation (tea), the term used in the tea industry for the aerobic treatment of tea leaves to break down certain unwanted chemicals and modify others to develop the flavor of the tea

Ferment may refer to:

• Ferment (album), by Catherine Wheel

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