Array ( [0] => {{Short description|Metabolic process producing energy in the absence of oxygen}} [1] => {{Other uses}} [2] => {{Distinguish|Anaerobic respiration}} [3] => [[File:Fermenting.jpg|thumb|Fermentation in progress: [[carbon dioxide]] bubbles form a froth on top of the fermentation mixture.]] [4] => [5] => '''Fermentation''' is a [[metabolism|metabolic]] process that produces chemical changes in organic [[chemical substance|substances]] through the action of [[enzyme]]s. In [[biochemistry]], it is broadly defined as the extraction of energy from [[carbohydrate]]s in the absence of [[oxygen]]. [[Fermentation in food processing|In food production]], it may more broadly refer to any process in which the activity of [[microorganism]]s brings about a desirable change to a foodstuff or beverage.{{cite book | last=Hui | first=Y. H. | title=Handbook of vegetable preservation and processing | publisher=M. Dekker | location=New York | year=2004 | isbn=978-0-8247-4301-7 | oclc=52942889 | page=180}} The science of fermentation is known as [[zymology]]. [6] => [7] => In microorganisms, fermentation is the primary means of producing [[adenosine triphosphate]] (ATP) by the degradation of organic nutrients [[Anaerobic digestion|anaerobically]]. [8] => [9] => Humans have used fermentation to produce foodstuffs and beverages since the [[Neolithic]] age. For example, fermentation is used for preservation in a process that produces [[lactic acid]] found in such sour foods as [[pickled cucumber]]s, [[kombucha]], [[kimchi]], and [[yogurt]], as well as for [[fermentation in winemaking|producing alcoholic beverages such as wine]] and [[beer]]. Fermentation also occurs within the gastrointestinal tracts of all animals, including humans.{{cite web |last=Bowen |first=Richard |title=Microbial Fermentation |url=http://www.vivo.colostate.edu/hbooks/pathphys/digestion/largegut/ferment.html |access-date=29 April 2018 |website=Hypertexts for biological sciences |publisher=Colorado State University}} [10] => [11] => '''[[Industrial fermentation]]''' is a broader term used for the process of applying microbes for the large-scale production of chemicals, [[biofuel]]s, enzymes, proteins and pharmaceuticals. [12] => [13] => == Definitions and etymology == [14] => Below are some definitions of fermentation ranging from informal, general usages to more scientific definitions.{{cite book |last1=Tortora |first1=Gerard J. |last2=Funke |first2=Berdell R.|last3=Case|first3=Christine L. |title=Microbiology An Introduction |url=https://archive.org/details/microbiologyintr00tort_505 |url-access=limited |date=2010 |publisher=Pearson Benjamin Cummings |location=San Francisco, CA |isbn=978-0-321-58202-7 |page=[https://archive.org/details/microbiologyintr00tort_505/page/n167 135]|edition=10|ref=31|chapter=5}} [15] => # Preservation methods [[Fermentation in food processing|for food]] via microorganisms (general use). [16] => # Any large-scale microbial process occurring with or without air (common definition used in industry, also known as [[industrial fermentation]]). [17] => # Any process that produces alcoholic beverages or acidic dairy products (general use). [18] => # Any energy-releasing metabolic process that takes place only under anaerobic conditions (somewhat scientific). [19] => # Any metabolic process that releases energy from a sugar or other organic molecule, does not require oxygen or an electron transport system, and uses an organic molecule as the final electron acceptor (most scientific). [20] => [21] => The word "ferment" is derived from the Latin verb ''fervere'', which means to boil. It is thought to have been first used in the late 14th century in [[alchemy]], but only in a broad sense. It was not used in the modern scientific sense until around 1600.{{Citation needed|date=January 2021}} [22] => [23] => == Biological role == [24] => Along with [[aerobic respiration]], fermentation is a method to extract energy from molecules. This method is the only one common to all bacteria and [[eukaryote]]s. It is therefore considered the oldest [[metabolic pathway]], suitable for primeval environments{{snd}}before plant life on Earth, that is, before oxygen in the atmosphere.{{rp|389}} Nick Lane criticizes this proposal as the amount of energy released by fermentation is small, which can't lead to a thermodynamic driving force of prebiotic chemistry. The enzymes involved in fermentations, which are encoded by genes, could not have existed during prebiotic chemistry. In addition, he notes that the differences between the fermentation processes in archaea and bacteria indicate that fermentation likely evolved later on, developing independently in both types of primitive life.{{Cite journal |last1=Lane |first1=Nick |last2=Allen |first2=John F. |last3=Martin |first3=William |date=2010-01-27 |title=How did LUCA make a living? Chemiosmosis in the origin of life |url=https://onlinelibrary.wiley.com/doi/10.1002/bies.200900131 |journal=BioEssays |language=en |volume=32 |issue=4 |pages=271–280 |doi=10.1002/bies.200900131|pmid=20108228 }} [25] => [26] => [[Yeast]], a form of [[fungus]], occurs in almost any environment capable of supporting microbes, from the skins of fruits to the guts of insects and mammals to the deep ocean. Yeasts convert (break down) sugar-rich molecules to produce ethanol and carbon dioxide.{{cite journal|last1=Martini|first1=A.|s2cid=35231385|title=Biodiversity and conservation of yeasts|journal=Biodiversity and Conservation|date=1992|volume=1|issue=4|pages=324–333|doi=10.1007/BF00693768|bibcode=1992BiCon...1..324M }}{{cite journal|last1=Bass|first1=D.|last2=Howe|first2=A.|last3=Brown|first3=N.|last4=Barton|first4=H.|last5=Demidova|first5=M.|last6=Michelle|first6=H.|last7=Li|first7=L.|last8=Sanders|first8=H.|last9=Watkinson|first9=S. C|last10=Willcock|first10=S.|last11=Richards|first11=T. A|title=Yeast forms dominate fungal diversity in the deep oceans|journal=Proceedings of the Royal Society B: Biological Sciences|date=22 December 2007|volume=274|issue=1629|pages=3069–3077|doi=10.1098/rspb.2007.1067|pmid=17939990|pmc=2293941}} [27] => [28] => Basic mechanisms for fermentation remain present in all cells of higher organisms. [[Mammal]]ian [[muscle]] carries out fermentation during periods of intense exercise where oxygen supply becomes limited, resulting in the creation of [[lactic acid]].{{cite book|last1=Voet|first1=Donald|last2=Voet|first2=Judith G.|title=Biochemistry|date=2010|publisher=Wiley Global Education|isbn=9781118139936|edition=4th}}{{rp|63}} In [[invertebrates]], fermentation also produces [[succinate]] and [[alanine]].{{cite book|last1=Broda|first1=E|title=The Evolution of the Bioenergetic Processes|journal=Progress in Biophysics and Molecular Biology|date=2014|volume=21|pages=143–208|publisher=Elsevier|pmid=4913287|isbn=9781483136134}}{{rp|141}} [29] => [30] => Fermentative bacteria play an essential role in the production of [[methane]] in habitats ranging from the [[rumen]]s of cattle to sewage digesters and freshwater sediments. They produce hydrogen, carbon dioxide, [[formate]] and [[acetate]] and [[carboxylic acid]]s. Then consortia of microbes convert the carbon dioxide and acetate to methane. [[Acetogenic bacteria]] oxidize the acids, obtaining more acetate and either hydrogen or formate. Finally, [[methanogenesis|methanogens]] (in the domain ''[[Archea]]'') convert acetate to methane.{{cite journal|last1=Ferry|first1=J G|title=Methane from acetate.|journal=Journal of Bacteriology|date=September 1992|volume=174|issue=17|pages=5489–5495|doi=10.1128/jb.174.17.5489-5495.1992|pmid=1512186|pmc=206491}} [31] => [32] => == Biochemical overview == [33] => {{missing information|section|fermentation under "in-between" microaerobic conditions (see e.g. {{doi|10.1016/j.biotechadv.2012.11.005}}). Such conditions can support obligate anaerobes if there's an aerobe to remove the oxygen ({{doi|10.1186/s12934-016-0412-z}}).|date=April 2022}} [34] => [[File:Cellular respiration.gif|thumb|upright=1.2|Comparison of an aerobic respiration and most known fermentation types in [[Eukaryote|eukaryotic]] cell.{{cite book |last=Stryer |first=Lubert |year=1995 |title=Biochemistry |publisher=W. H. Freeman and Company |location=New York - Basingstoke |edition=fourth |isbn=978-0716720096 }} Numbers in circles indicate counts of carbon atoms in molecules, C6 is [[glucose]] C6H12O6, C1 [[carbon dioxide]] CO2. [[Mitochondrion|Mitochondrial]] outer membrane is omitted.]]Fermentation reacts the [[Redox|reduced]] form of [[nicotinamide adenine dinucleotide]] (NADH) with an [[Endogeny|endogenous]], [[organic compound|organic]] [[electron acceptor]].{{cite book|author1=Klein, Donald W.|url=http://highered.mcgraw-hill.com/sites/0072556781/information_center_view0/|title=Microbiology|author2=Lansing M.|author3=Harley, John|publisher=[[McGraw-Hill]]|year=2006|isbn=978-0-07-255678-0|edition=6th|location=New York}} Usually this is [[pyruvate]] formed from sugar through [[glycolysis]]. The reaction produces oxidized NAD+ and an organic product, typical examples being [[ethanol]], [[lactic acid]], and [[hydrogen]] gas (H2), and often also [[carbon dioxide]]. However, more exotic compounds can be produced by fermentation, such as [[butyric acid]] and [[acetone]]. Fermentation products are considered waste products, since they cannot be metabolized further without the use of oxygen.{{cn|date=June 2022}} [35] => [36] => Fermentation normally occurs in an [[anaerobic environment]]. In the presence of O2, NADH, and pyruvate are used to generate [[adenosine triphosphate]] (ATP) in [[Cellular respiration|respiration]]. This is called [[oxidative phosphorylation]]. This generates much more ATP than glycolysis alone. For this reason, fermentation is rarely used when oxygen is available. However, even in the presence of abundant oxygen, some strains of [[yeast]] such as ''[[Saccharomyces cerevisiae]]'' prefer fermentation to [[aerobic respiration]] as long as there is an adequate supply of [[Sugar#Chemistry|sugars]] (a phenomenon known as the [[Crabtree effect]]).{{cite book|last1=Piškur|first1=Jure|last2=Compagno|first2=Concetta|title=Molecular mechanisms in yeast carbon metabolism|date=2014|publisher=Springer|isbn=9783642550133|page=12}} Some fermentation processes involve [[obligate anaerobe]]s, which cannot tolerate oxygen.{{Citation needed|date=January 2021}} [37] => [38] => Although [[yeast]] carries out the [[fermentation (food)|fermentation]] in the production of [[ethanol]] in [[beer]]s, [[wine]]s, and other alcoholic drinks, this is not the only possible agent: [[bacteria]] carry out the fermentation in the production of [[xanthan gum]].{{Citation needed|date=January 2021}} [39] => [40] => == Products of fermentation == [41] => [42] => === Ethanol === [43] => {{Main|Ethanol fermentation}} [44] => [45] => In ethanol fermentation, one glucose molecule is converted into two ethanol molecules and two [[carbon dioxide]] (CO2) molecules.{{cite book|last1=Purves|first1=William K.|last2=Sadava|first2=David E.|last3=Orians|first3=Gordon H.|last4=Heller|first4=H. Craig|title=Life, the science of biology|url=https://archive.org/details/lifesciencebiolo00purv_787|url-access=limited|date=2003|publisher=Sinauer Associates|location=Sunderland, Mass.|isbn=978-0-7167-9856-9|pages=[https://archive.org/details/lifesciencebiolo00purv_787/page/n141 139]–40|edition=7th}}{{cite book|title=Biochemistry|author=Stryer, Lubert|year=1975|publisher=W. H. Freeman and Company|isbn=978-0-7167-0174-3|url=https://archive.org/details/biochemistry00stry_1}} It is used to make bread dough rise: the carbon dioxide forms bubbles, expanding the dough into a foam.{{cite journal|last1=Logan|first1=BK|last2=Distefano|first2=S|title=Ethanol content of various foods and soft drinks and their potential for interference with a breath-alcohol test.|journal=Journal of Analytical Toxicology|date=1997|volume=22|issue=3|pages=181–83|pmid=9602932|doi=10.1093/jat/22.3.181|doi-access=}}{{cite journal|title=The Alcohol Content of Bread.|journal=Canadian Medical Association Journal|date=November 1926|volume=16|issue=11|pages=1394–95|pmid=20316063|pmc=1709087}} The ethanol is the intoxicating agent in alcoholic beverages such as wine, beer and liquor.{{cite web|title=Alcohol|url=https://www.drugs.com/alcohol.html|website=Drugs.com|access-date=26 April 2018}} Fermentation of feedstocks, including [[sugarcane]], [[maize]], and [[sugar beets]], produces ethanol that is added to [[gasoline]].{{cite web|url=http://www.rurdev.usda.gov/rbs/pub/sep06/ethanol.htm|title=Ethanol from Sugar|author=James Jacobs, Ag Economist|publisher=United States Department of Agriculture|access-date=2007-09-04|url-status=dead|archive-url=https://web.archive.org/web/20070910023203/http://www.rurdev.usda.gov/rbs/pub/sep06/ethanol.htm|archive-date=2007-09-10}} In some species of fish, including [[goldfish]] and [[carp]], it provides energy when oxygen is scarce (along with lactic acid fermentation).{{cite book|first1=Aren |last1=van Waarde|first2=G. Van den |last2=Thillart|first3=Maria |last3=Verhagen|title=Surviving Hypoxia|date=1993|isbn=978-0-8493-4226-4|pages=157–70|chapter=Ethanol Formation and pH-Regulation in Fish|publisher=CRC Press }} [46] => [47] => Before fermentation, a glucose molecule breaks down into two pyruvate molecules ([[glycolysis]]). The energy from this [[exothermic reaction]] is used to bind inorganic [[phosphate]]s to ADP, which converts it to ATP, and convert NAD+ to NADH. The pyruvates break down into two [[acetaldehyde]] molecules and give off two carbon dioxide molecules as waste products. The acetaldehyde is reduced into ethanol using the energy and hydrogen from NADH, and the NADH is oxidized into NAD+ so that the cycle may repeat. The reaction is catalyzed by the enzymes pyruvate decarboxylase and alcohol dehydrogenase. [48] => [49] => ==== History of bioethanol fermentation ==== [50] => {{More citations needed section|date=August 2023}} [51] => The history of ethanol as a fuel spans several centuries and is marked by a series of significant milestones. Samuel Morey, an American inventor, was the first to produce ethanol by fermenting corn in 1826. However, it was not until the California Gold Rush in the 1850s that ethanol was first used as a fuel in the United States. Rudolf Diesel demonstrated his engine, which could run on vegetable oils and ethanol, in 1895, but the widespread use of petroleum-based diesel engines made ethanol less popular as a fuel. In the 1970s, the oil crisis reignited interest in ethanol, and Brazil became a leader in ethanol production and use. The United States began producing ethanol on a large scale in the 1980s and 1990s as a fuel additive to gasoline, due to government regulations. Today, ethanol continues to be explored as a sustainable and renewable fuel source, with researchers developing new technologies and biomass sources for its production. [52] => [53] => * 1826: Samuel Morey, an American inventor, was the first to produce ethanol by fermenting corn. However, ethanol was not widely used as a fuel until many years later. (1) [54] => * 1850s: Ethanol was first used as a fuel in the United States during the California Gold Rush. Miners used ethanol as a fuel for lamps and stoves because it was cheaper than whale oil. (2) [55] => * 1895: German engineer Rudolf Diesel demonstrated his engine, which was designed to run on vegetable oils, including ethanol. However, the widespread use of diesel engines fueled by petroleum made ethanol less popular as a fuel. (3) [56] => * 1970s: The oil crisis of the 1970s led to renewed interest in ethanol as a fuel. Brazil became a leader in ethanol production and use, due in part to government policies that encouraged the use of biofuels. (4) [57] => * 1980s–1990s: The United States began to produce ethanol on a large scale as a fuel additive to gasoline. This was due to the passage of the Clean Air Act in 1990, which required the use of oxygenates, such as ethanol, to reduce emissions. (5) [58] => * 2000s–present: There has been continued interest in ethanol as a renewable and sustainable fuel. Researchers are exploring new sources of biomass for ethanol production, such as switchgrass and algae, and developing new technologies to improve the efficiency of the fermentation process. (6) [59] => [60] => === Lactic acid === [61] => {{Main|Lactic acid fermentation}} [62] => {{See also|Mixed acid fermentation}} [63] => {{More citations needed section|date=January 2021}} [64] => [65] => ''Homolactic fermentation'' (producing only lactic acid) is the simplest type of fermentation. Pyruvate from glycolysisIntroductory Botany: plants, people, and the Environment. Berg, Linda R. Cengage Learning, 2007. {{ISBN|978-0-534-46669-5}}. p. 86 undergoes a simple redox reaction, forming [[lactic acid]].AP Biology. Anestis, Mark. 2nd Edition. McGraw-Hill Professional. 2006. {{ISBN|978-0-07-147630-0}}. p. 61A dictionary of applied chemistry, Volume 3. Thorpe, Sir Thomas Edward. Longmans, Green and Co., 1922. p.159 Overall, one molecule of glucose (or any six-carbon sugar) is converted to two molecules of lactic acid: [66] => :C6H12O6 → 2 CH3CHOHCOOH [67] => It occurs in the muscles of animals when they need energy faster than the [[blood]] can supply oxygen. It also occurs in some kinds of [[bacterium|bacteria]] (such as [[lactobacilli]]) and some [[fungi]]. It is the type of bacteria that convert [[lactose]] into lactic acid in [[yogurt]], giving it its sour taste. These lactic acid bacteria can carry out either [[homolactic fermentation]], where the end-product is mostly lactic acid, or ''heterolactic fermentation'', where some lactate is further metabolized to ethanol and carbon dioxide (via the [[phosphoketolase]] pathway), acetate, or other metabolic products, e.g.: [68] => :C6H12O6 → CH3CHOHCOOH + C2H5OH + CO2 [69] => If lactose is fermented (as in yogurts and cheeses), it is first converted into glucose and galactose (both six-carbon sugars with the same atomic formula): [70] => :C12H22O11 + H2O → 2 C6H12O6 [71] => Heterolactic fermentation is in a sense intermediate between [[lactic acid fermentation]] and other types, e.g. [[alcoholic fermentation]]. Reasons to go further and convert lactic acid into something else include: [72] => * The acidity of lactic acid impedes biological processes. This can be beneficial to the fermenting organism as it drives out competitors that are unadapted to the acidity. As a result, the food will have a longer shelf life (one reason foods are purposely fermented in the first place); however, beyond a certain point, the acidity starts affecting the organism that produces it. [73] => * The high concentration of lactic acid (the final product of fermentation) drives the equilibrium backwards ([[Le Chatelier's principle]]), decreasing the rate at which fermentation can occur and slowing down growth. [74] => * Ethanol, into which lactic acid can be easily converted, is volatile and will readily escape, allowing the reaction to proceed easily. CO2 is also produced, but it is only weakly acidic and even more volatile than ethanol. [75] => * Acetic acid (another conversion product) is acidic and not as volatile as ethanol; however, in the presence of limited oxygen, its creation from lactic acid releases additional energy. It is a lighter molecule than lactic acid, forming fewer hydrogen bonds with its surroundings (due to having fewer groups that can form such bonds), thus is more volatile and will also allow the reaction to proceed more quickly. [76] => * If [[propionic acid]], [[butyric acid]], and longer monocarboxylic acids are produced, the amount of acidity produced per glucose consumed will decrease, as with ethanol, allowing faster growth. [77] => [78] => === Hydrogen gas === [79] => {{Main|Fermentative hydrogen production}} [80] => [[Hydrogen]] gas is produced in many types of fermentation as a way to regenerate NAD+ from NADH. [[Electron]]s are transferred to [[ferredoxin]], which in turn is oxidized by [[hydrogenase]], producing H2. Hydrogen gas is a [[Substrate (biochemistry)|substrate]] for [[methanogen]]s and [[Sulfate-reducing microorganisms|sulfate reducer]]s, which keep the concentration of hydrogen low and favor the production of such an energy-rich compound,{{cite book [81] => | last1 = Madigan [82] => | first1 = Michael T. [83] => | last2 = Martinko [84] => | first2 = John M. [85] => | last3 = Parker [86] => | first3 = Jack [87] => | year = 1996 [88] => | title = Brock biology of microorganisms [89] => | edition = 8th [90] => | publisher = [[Prentice Hall]] [91] => | isbn = 978-0-13-520875-5 [92] => | url = https://archive.org/details/brockbiologyofmi0000madi [93] => | access-date = 2010-07-12 [94] => | url-access = registration [95] => }} but hydrogen gas at a fairly high concentration can nevertheless be formed, as in [[flatus]].{{Citation needed|date=January 2021}} [96] => [97] => For example, ''[[Clostridium pasteurianum]]'' ferments glucose to [[butyric acid|butyrate]], [[acetic acid|acetate]], carbon dioxide, and hydrogen gas:{{Cite journal | last1 = Thauer | first1 = R.K. [98] => | last2 = Jungermann | first2 = K. | last3 = Decker | first3 = K. | year = 1977 | title = Energy conservation in chemotrophic anaerobic bacteria | journal = Bacteriological Reviews | volume = 41 | issue = 1 | pages = 100–80 | issn = 0005-3678 | pmid=860983 | pmc=413997| doi = 10.1128/MMBR.41.1.100-180.1977 [99] => }} The reaction leading to acetate is: [100] => [101] => :C6H12O6 + 4 H2O → 2 CH3COO + 2 HCO3 + 4 H+ + 4 H2 [102] => [103] => === Other === [104] => Other types of fermentation include [[mixed acid fermentation]], [[butanediol fermentation]], [[butyrate fermentation]], [[caproate fermentation]], [[acetone–butanol–ethanol fermentation]], and [[glyoxylate fermentation]].{{Citation needed|date=January 2021}} [105] => [106] => === In the broader sense === [107] => In food and industrial contexts, any chemical modification performed by a living being in a controlled container can be termed "fermentation". The following do not fall into the biochemical sense, but are called fermentation in the larger sense: [108] => [109] => ==== Alternative protein ==== [110] => {{See|List of fermented foods}} [111] => [[File:Impossible Burger - Gott's Roadside- 2018 - Stierch.jpg|thumb|Fermentation is used to produce the [[heme protein]] found in the [[Impossible Burger]].]] [112] => [113] => Fermentation can be used to make alternative protein sources. It is commonly used to modify existing protein foods, including plant-based ones such as soy, into more flavorful forms such as [[tempeh]] and [[fermented tofu]]. [114] => [115] => More modern "fermentation" makes [[recombinant protein]] to help produce [[meat analogue]], [[milk substitute]], [[cheese analogue]]s, and [[egg substitute]]s. Some examples are:{{cite web |author1=Flora Southey |title=What's next in alternative protein? 7 trends on the up in 2022 |url=https://www.foodnavigator.com/Article/2022/01/27/what-s-next-in-alternative-protein-7-trends-on-the-up-in-2022 |publisher=Food-Navigator.com, William Reed Business Media |access-date=27 January 2022 |date=27 January 2022}} [116] => * Recombinant [[myoglobin]] for faux meat (Motif Foodworks) [117] => * Recombinant [[leghemoglobin]] for faux meat ([[Impossible Foods]]) [118] => * Recombinant whey for dairy replacement (Perfect Day) [119] => * Recombinant egg white (EVERY) [120] => [121] => [[Heme protein]]s such as myoglobin and [[hemoglobin]] give meat its characteristic texture, flavor, color, and aroma. The myoglobin and leghemoglobin ingredients can be used to replicate this property, despite them coming from a vat instead of meat.{{Cite magazine|title=Inside the Strange Science of the Fake Meat That 'Bleeds'|language=en-us|magazine=Wired|url=https://www.wired.com/story/the-impossible-burger/|access-date=2020-10-28|issn=1059-1028|author=Matt Simon|date=2017-09-20}} [122] => [123] => ==== Enzymes ==== [124] => [[Industrial fermentation]] can be used for enzyme production, where proteins with catalytic activity are produced and secreted by microorganisms. The development of fermentation processes, microbial strain engineering and recombinant gene technologies has enabled the commercialization of a wide range of enzymes. [[Enzyme]]s are used in all kinds of industrial segments, such as food (lactose removal, cheese flavor), beverage (juice treatment), baking (bread softness, dough conditioning), animal feed, detergents (protein, starch and lipid stain removal), textile, personal care and pulp and paper industries.{{Cite journal|last1=Kirk|first1=Ole|last2=Borchert|first2=Torben Vedel|last3=Fuglsang|first3=Claus Crone|date=2002-08-01|title=Industrial enzyme applications|url=https://www.sciencedirect.com/science/article/pii/S0958166902003282|journal=Current Opinion in Biotechnology|language=en|volume=13|issue=4|pages=345–351|doi=10.1016/S0958-1669(02)00328-2|pmid=12323357 |issn=0958-1669}} [125] => [126] => == Modes of industrial operation == [127] => Most [[industrial fermentation]] uses batch or fed-batch procedures, although continuous fermentation can be more economical if various challenges, particularly the difficulty of maintaining sterility, can be met.{{cite journal|last1=Li|first1=Teng|last2=Chen|first2=Xiang-bin|last3=Chen|first3=Jin-chun|last4=Wu|first4=Qiong|last5=Chen|first5=Guo-Qiang|title=Open and continuous fermentation: Products, conditions and bioprocess economy|journal=Biotechnology Journal|date=December 2014|volume=9|issue=12|pages=1503–1511|doi=10.1002/biot.201400084|pmid=25476917|s2cid=21524147}} [128] => [129] => === Batch === [130] => In a batch process, all the ingredients are combined and the reactions proceed without any further input. Batch fermentation has been used for millennia to make bread and alcoholic beverages, and it is still a common method, especially when the process is not well understood.{{cite book|last1=Cinar|first1=Ali|last2=Parulekar|first2=Satish J.|last3=Undey|first3=Cenk|last4=Birol|first4=Gulnur|title=Batch fermentation modeling, monitoring, and control.|date=2003|publisher=Marcel Dekker|location=New York|isbn=9780203911358}}{{rp|1}} However, it can be expensive because the fermentor must be sterilized using high pressure steam between batches. Strictly speaking, there is often addition of small quantities of chemicals to control the pH or suppress foaming.{{rp|25}} [131] => [132] => Batch fermentation goes through a series of phases. There is a lag phase in which cells adjust to their environment; then a phase in which exponential growth occurs. Once many of the nutrients have been consumed, the growth slows and becomes non-exponential, but production of ''secondary metabolites'' (including commercially important antibiotics and enzymes) accelerates. This continues through a stationary phase after most of the nutrients have been consumed, and then the cells die.{{rp|25}} [133] => [134] => === Fed-batch === [135] => {{See also|Fed-batch culture}} [136] => Fed-batch fermentation is a variation of batch fermentation where some of the ingredients are added during the fermentation. This allows greater control over the stages of the process. In particular, production of secondary metabolites can be increased by adding a limited quantity of nutrients during the non-exponential growth phase. Fed-batch operations are often sandwiched between batch operations.{{rp|1}}{{cite book|last1=Schmid|first1=Rolf D.|last2=Schmidt-Dannert|first2=Claudia|title=Biotechnology : an illustrated primer|date=2016|publisher=John Wiley & Sons|isbn=9783527335152|edition=Second|page=92}} [137] => [138] => === Open === [139] => The high cost of sterilizing the fermentor between batches can be avoided using various open fermentation approaches that are able to resist contamination. One is to use a naturally evolved mixed culture. This is particularly favored in wastewater treatment, since mixed populations can adapt to a wide variety of wastes. [[Thermophile|Thermophilic]] bacteria can produce lactic acid at temperatures of around 50 °Celsius, sufficient to discourage microbial contamination; and ethanol has been produced at a temperature of 70 °C. This is just below its boiling point (78 °C), making it easy to extract. [[Halophiles|Halophilic]] bacteria can produce bioplastics in hypersaline conditions. Solid-state fermentation adds a small amount of water to a solid substrate; it is widely used in the food industry to produce flavors, enzymes and organic acids. [140] => [141] => === Continuous === [142] => In continuous fermentation, substrates are added and final products removed continuously. There are three varieties: [[chemostat]]s, which hold nutrient levels constant; [[turbidostat]]s, which keep cell mass constant; and [[Plug flow reactor model|plug flow reactors]] in which the culture medium flows steadily through a tube while the cells are recycled from the outlet to the inlet. If the process works well, there is a steady flow of feed and effluent and the costs of repeatedly setting up a batch are avoided. Also, it can prolong the exponential growth phase and avoid byproducts that inhibit the reactions by continuously removing them. However, it is difficult to maintain a steady state and avoid contamination, and the design tends to be complex. Typically the fermentor must run for over 500 hours to be more economical than batch processors. [143] => [144] => == History of the use of fermentation == [145] => {{Main|Fermentation in food processing}} [146] => The use of fermentation, particularly for [[alcoholic beverage|beverages]], has existed since the [[Neolithic]] and has been documented dating from 7000 to 6600 BCE in [[Jiahu]], [[Neolithic China|China]],{{Cite journal | last1 = McGovern | first1 = P. E. | last2 = Zhang | first2 = J. | last3 = Tang | first3 = J. | last4 = Zhang | first4 = Z. | last5 = Hall | first5 = G. R. | last6 = Moreau | first6 = R. A. | last7 = Nunez | first7 = A. | last8 = Butrym | first8 = E. D. | last9 = Richards | first9 = M. P. | last10 = Wang | first10 = C. -S. | last11 = Cheng | first11 = G. | last12 = Zhao | first12 = Z. | last13 = Wang | first13 = C. | title = Fermented beverages of pre- and proto-historic China | doi = 10.1073/pnas.0407921102 | journal = Proceedings of the National Academy of Sciences | volume = 101 | issue = 51 | pages = 17593–17598 | year = 2004 | pmid = 15590771| pmc = 539767| bibcode = 2004PNAS..10117593M | doi-access = free }} 5000 BCE in India, Ayurveda mentions many Medicated Wines, 6000 BCE in Georgia,{{Cite journal | last1 = Vouillamoz | first1 = J. F. | last2 = McGovern | first2 = P. E. | last3 = Ergul | first3 = A. | last4 = Söylemezoğlu | first4 = G. K. | last5 = Tevzadze | first5 = G. | last6 = Meredith | first6 = C. P. | last7 = Grando | first7 = M. S. | doi = 10.1079/PGR2006114 | title = Genetic characterization and relationships of traditional grape cultivars from Transcaucasia and Anatolia | journal = Plant Genetic Resources: Characterization and Utilization | volume = 4 | issue = 2 | pages = 144–158 | year = 2006 | citeseerx = 10.1.1.611.7102 | s2cid = 85577497 }} 3150 BCE in [[ancient Egypt]],{{cite journal |last=Cavalieri |first=D |author2=McGovern P.E. |author3=Hartl D.L. |author4=Mortimer R. |author5=Polsinelli M. |year=2003 |title=Evidence for S. cerevisiae fermentation in ancient wine |journal=Journal of Molecular Evolution |volume=57 |issue=Suppl 1 |pages=S226–32 |id=15008419 |url=http://www.oeb.harvard.edu/hartl/lab/publications/pdfs/Cavalieri-03-JME.pdf|access-date=2007-01-28|doi=10.1007/s00239-003-0031-2 |pmid= 15008419 |archive-url = https://web.archive.org/web/20061209165920/http://www.oeb.harvard.edu/hartl/lab/publications/pdfs/Cavalieri-03-JME.pdf |archive-date=December 9, 2006 |url-status=dead|citeseerx = 10.1.1.628.6396|bibcode=2003JMolE..57S.226C |s2cid=7914033 }} 3000 BCE in [[Babylon]],{{cite web |url=http://www.fao.org/docrep/x0560e/x0560e05.htm |title=Fermented fruits and vegetables. A global perspective |access-date=2007-01-28 |work=FAO Agricultural Services Bulletins - 134 |archive-url=https://web.archive.org/web/20070119162605/http://www.fao.org/docrep/x0560e/x0560e05.htm |archive-date=January 19, 2007 |url-status=dead }} 2000 BCE in pre-Hispanic Mexico, and 1500 BC in [[Sudan]].Dirar, H., (1993), The Indigenous Fermented Foods of the Sudan: A Study in African Food and Nutrition, CAB International, UK Fermented foods have a religious significance in [[Chametz|Judaism]] and [[Christianity and alcohol|Christianity]]. The [[Baltic mythology|Baltic god]] Rugutis was worshiped as the agent of fermentation.{{cite web|url=http://www.spauda.lt/mitai/lietuva/lietdiev.htm|title=Gintaras Beresneviius. M. Strijkovskio Kronikos" lietuvi diev sraas|work=spauda.lt|access-date=2013-10-27|archive-date=2020-06-26|archive-url=https://web.archive.org/web/20200626081727/http://www.spauda.lt/mitai/lietuva/lietdiev.htm|url-status=dead}}Rūgutis. Mitologijos enciklopedija, 2 tomas. Vilnius. Vaga. 1999. 293 p. [147] => In [[alchemy]], fermentation ("putrefaction") was [[alchemical symbols|symbolized]] by [[Capricorn (astrology)|Capricorn]] [[Image:Capricornus symbol (fixed width).svg|16px]] ♑︎. [148] => [149] => [[File:Portrait of Louis Pasteur in his laboratory Wellcome M0010355.jpg|thumb|Louis Pasteur in his laboratory]] [150] => In 1837, [[Charles Cagniard de la Tour]], [[Theodor Schwann]] and [[Friedrich Traugott Kützing]] independently published papers concluding, as a result of microscopic investigations, that yeast is a living organism that reproduces by [[budding]].{{cite web|last1=Shurtleff|first1=William|last2=Aoyagi|first2=Akiko|title=A Brief History of Fermentation, East and West|url=http://www.soyinfocenter.com/HSS/fermentation.php|website=Soyinfo Center|publisher=Soyfoods Center, Lafayette, California|access-date=30 April 2018}}{{cite book|editor-last1=Lengeler|editor-first1=Joseph W.|editor-last2=Drews|editor-first2=Gerhart|editor-last3=Schlegel|editor-first3=Hans Günter|title=Biology of the prokaryotes|date=1999|publisher=Thieme [u.a.]|location=Stuttgart|isbn=9783131084118}}{{rp|6}} Schwann boiled grape juice to kill the yeast and found that no fermentation would occur until new yeast was added. However, a lot of chemists, including [[Antoine Lavoisier]], continued to view fermentation as a simple chemical reaction and rejected the notion that living organisms could be involved. This was seen as a reversion to [[vitalism]] and was lampooned in an anonymous publication by [[Justus von Liebig]] and [[Friedrich Wöhler]].{{cite book|last1=Tobin|first1=Allan|last2=Dusheck|first2=Jennie|title=Asking about life|date=2005|publisher=Brooks/Cole|location=Pacific Grove, Calif.|isbn=9780534406530|edition=3rd}}{{rp|108–109}} [151] => [152] => The turning point came when [[Louis Pasteur]] (1822–1895), during the 1850s and 1860s, repeated Schwann's experiments and showed fermentation is initiated by living organisms in a series of investigations.{{rp|6}} In 1857, Pasteur showed lactic acid fermentation is caused by living organisms.[http://www.fjcollazo.com/fjc_publishings/documents/LPasteurRpt.htm Accomplishments of Louis Pasteur] {{webarchive|url=https://web.archive.org/web/20101130000148/http://www.fjcollazo.com/fjc_publishings/documents/LPasteurRpt.htm |date=2010-11-30 }}. Fjcollazo.com (2005-12-30). Retrieved on 2011-01-04. In 1860, he demonstrated how bacteria cause [[souring]] in milk, a process formerly thought to be merely a chemical change. His work in identifying the role of microorganisms in food spoilage led to the process of [[pasteurization]].[http://science.howstuffworks.com/dictionary/famous-scientists/chemists/louis-pasteur-info.htm HowStuffWorks "Louis Pasteur"]. Science.howstuffworks.com (2009-07-01). Retrieved on 2011-01-04. [153] => [154] => In 1877, working to improve the French [[brewing industry]], Pasteur published his famous paper on fermentation, "''Etudes sur la Bière''", which was translated into English in 1879 as "Studies on fermentation".Louis Pasteur (1879) Studies on fermentation: The diseases of beer, their causes, and the means of preventing them. Macmillan Publishers. He defined fermentation (incorrectly) as "Life without air",Modern History Sourcebook: Louis Pasteur (1822–1895): Physiological theory of fermentation, 1879. Translated by F. Faulkner, D.C. Robb. yet he correctly showed how specific types of microorganisms cause specific types of fermentations and specific end-products.{{Citation needed|date=January 2021}} [155] => [156] => Although showing fermentation resulted from the action of living microorganisms was a breakthrough, it did not explain the basic nature of fermentation; nor did it prove it is caused by microorganisms which appear to be always present. Many scientists, including Pasteur, had unsuccessfully attempted to extract the fermentation enzyme from [[yeast]]. [157] => [158] => Success came in 1897 when the German chemist [[Eduard Buechner]] ground up yeast, extracted a juice from them, then found to his amazement this "dead" liquid would ferment a sugar solution, forming carbon dioxide and alcohol much like living yeasts.[https://books.google.com/books?id=HFrBP8S7my4C&pg=PA25 New beer in an old bottle]: Eduard Buchner and the Growth of Biochemical Knowledge. [[Cornish-Bowden, Athel]]. Universitat de Valencia. 1997. {{ISBN|978-84-370-3328-0}}. p. 25. [159] => [160] => Buechner's results are considered to mark the birth of biochemistry. The "unorganized ferments" behaved just like the organized ones. From that time on, the term enzyme came to be applied to all ferments. It was then understood fermentation is caused by enzymes produced by microorganisms.[https://archive.org/details/enigmaoffermentf0000lage/page/7 The enigma of ferment: from the philosopher's stone to the first biochemical Nobel prize]. Lagerkvist, Ulf. World Scientific Publishers. 2005. {{ISBN|978-981-256-421-4}}. p. 7. In 1907, Buechner won the [[Nobel Prize in chemistry]] for his work.A treasury of world science, Volume 1962, Part 1. Runes, Dagobert David. Philosophical Library Publishers. 1962. p. 109. [161] => [162] => Advances in microbiology and fermentation technology have continued steadily up until the present. For example, in the 1930s, it was discovered microorganisms could be [[mutation|mutated]] with physical and chemical treatments to be higher-yielding, faster-growing, tolerant of less oxygen, and able to use a more concentrated medium.{{cite book |last1=Steinkraus |first1=Keith |title=Handbook of Indigenous Fermented Foods |date=2018 |publisher=CRC Press |isbn=9781351442510 |edition=Second}}{{cite journal|last1=Wang|first1=H. L.|last2=Swain|first2=E. W.|last3=Hesseltine|first3=C. W.|title=Phytase of molds used in oriental food fermentation|journal=Journal of Food Science|volume=45|pages=1262–1266|year=1980|doi=10.1111/j.1365-2621.1980.tb06534.x|issue=5}} Strain [[Selection (biology)|selection]] and [[Hybrid (biology)|hybridization]] developed as well, affecting most modern food fermentations.{{Citation needed|date=January 2021}} [163] => [164] => === Post 1930s === [165] => The field of fermentation has been critical to the production of a wide range of consumer goods, from food and drink to industrial chemicals and pharmaceuticals. Since its early beginnings in ancient civilizations, the use of fermentation has continued to evolve and expand, with new techniques and technologies driving advances in product quality, yield, and efficiency. The period from the 1930s onward saw a number of significant advancements in fermentation technology, including the development of new processes for producing high-value products like antibiotics and enzymes, the increasing importance of fermentation in the production of bulk chemicals, and a growing interest in the use of fermentation for the production of [[functional food]]s and nutraceuticals. [166] => [167] => The 1950s and 1960s saw the development of new fermentation technologies, such as the use of immobilized cells and enzymes, which allowed for more precise control over fermentation processes and increased the production of high-value products like antibiotics and enzymes.In the 1970s and 1980s, fermentation became increasingly important in the production of bulk chemicals like ethanol, lactic acid, and citric acid. This led to the development of new fermentation techniques and the use of genetically engineered microorganisms to improve yields and reduce production costs. In the 1990s and 2000s, there was a growing interest in the use of fermentation for the production of functional foods and nutraceuticals, which have potential health benefits beyond basic nutrition. This led to the development of new fermentation processes and the use of probiotics and other functional ingredients. [168] => [169] => Overall, the period from 1930 onward saw significant advancements in the use of fermentation for industrial purposes, leading to the production of a wide range of fermented products that are now consumed around the world. [170] => [171] => == See also == [172] => {{Portal|Biology|Technology}} [173] => {{EB1911 poster|Fermentation}} [174] => {{columnslist|colwidth=20em| [175] => * [[List of fermented foods]] [176] => * [[Aerobic fermentation]] [177] => * [[Acetone-butanol-ethanol fermentation]] [178] => * [[Dark fermentation]] [179] => * [[Disproportionation#Biochemistry]] [180] => * [[Fermentation lock]] [181] => * [[Gut fermentation syndrome]] [182] => * [[Industrial fermentation]] [183] => * [[Non-fermenter]] [184] => * [[Photofermentation]] [185] => * [[Symbiotic fermentation]] [186] => }} [187] => [188] => == References == [189] => {{Reflist}} [190] => [191] => == External links == [192] => {{Commons category}} [193] => * [https://web.archive.org/web/20100624074721/http://www.pasteurbrewing.com/articles/works-of-louis-pasteur.html Works of Louis Pasteur] – Pasteur Brewing (archived 24 June 2010) [194] => * [https://web.archive.org/web/20080917123419/http://www2.ufp.pt/~pedros/bq/respi.htm The chemical logic behind fermentation and respiration] (archived 17 September 2008) [195] => [196] => {{Carbohydrate metabolism}} [197] => {{MetabolismMap}} [198] => {{Authority control}} [199] => [200] => [[Category:Fermentation| ]] [201] => [[Category:Anaerobic digestion]] [202] => [[Category:Oenology]] [203] => [[Category:Fermented drinks|*]] [204] => [[Category:Brewing]] [205] => [[Category:Food science]] [206] => [[Category:Metabolism]] [207] => [[Category:Food preservation]] [208] => [[Category:Alchemical processes]] [209] => [[Category:Mycology]] [210] => [[Category:Catalysis]] [] => )
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Fermentation

Fermentation is a metabolic process that converts sugar into acids, gases, or alcohol. It is an ancient technique used for the preservation of food, the production of alcoholic beverages, and the manufacture of various products such as bread, cheese, and yogurt.

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It is an ancient technique used for the preservation of food, the production of alcoholic beverages, and the manufacture of various products such as bread, cheese, and yogurt. This process occurs in the absence of oxygen and relies on the action of microorganisms, mainly yeasts and bacteria, to break down the sugar molecules and produce energy in the form of carbon dioxide and/or alcohol. Fermentation has been practiced for thousands of years by various cultures around the world and continues to play a significant role in modern industrial processes. This Wikipedia page provides a detailed explanation of the process of fermentation, its history, types and applications, as well as its potential benefits and drawbacks.

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