Editing Lactic acid fermentation (section)

==History==
Chemical analysis of archaeological finds show that milk fermentation had been used since prehistory; its first applications were probably a part of the [[Neolithic Revolution]]. Since milk naturally contains [[lactic acid bacteria]], the discovery of the fermentation process was quite evident, since it happens spontaneously at an adequate temperature. The problem of these first [[farmer]]s was that fresh milk is nearly indigestible by adults, so they had an interest to discover this mechanism. In fact, lactic acid bacteria contain the needed [[enzyme]]s to digest lactose, and their [[populations]] multiply strongly during the fermentation. Therefore, milk fermented even a short time contains enough enzymes to digest the lactose molecules, after the milk is in the human body, which allows adults to consume it. Even safer was a longer fermentation, which was practiced for [[cheesemaking]]. This process was also discovered a very long time ago, which is proven by recipes for cheese production on [[Cuneiform script]]s, the first written documents that exist, and  later in [[Babylonia]]n and Egyptian texts. There is a theory of [[competitive advantage]] related to fermented milk products. This theory suggests that the women of these first settled agricultural civilisations could shorten the time between two children thanks to the additional lactose uptake from milk consumption. This factor may have given them an important advantage to out-compete the [[hunter-gatherer]] societies.<ref name="hist">{{cite book |last1=Shurtleff |first1=William |last2=Aoyagi |first2=Akiko |title=A Brief History of Fermentation, East and West. In History of Soybeans and Soyfoods, 1100 B.C. to the 1980s |year=2004 |publisher=Ten Speed Press |isbn=1-58008-336-6}}</ref> 

With the increasing consumption of milk products these societies developed a [[lactase persistence]] by [[Epigenetics|epigenetic]] inheritance, which means that the milk-digesting enzyme [[lactase]] was present in their bodies during the whole lifetime, so they could drink unfermented milk as adults too. This early habituation to lactose consumption in the first [[Settler society|settler societies]] can still be observed today in regional differences of this mutation's concentration. It is estimated that about 65% of world population still lacks it.<ref name="lactase">{{cite book |last = Brüssow |first = Harald |title = Nutrition, population growth and disease: a short history of lactose. in Environmental Microbiology Volume 15, pages 2154–2161 |year = 2013 }}</ref> Since these first societies came from regions around eastern [[Turkey]] to central [[Europe]], the [[gene]] appears more frequently there and in North America, as it was settled by Europeans. It is because of the dominance of this mutation that [[Western culture|Western]] cultures believe it is unusual to have a [[lactose intolerance]], when it is in fact more common than the [[mutation]]. On the contrary, [[lactose intolerance]] is much more present in Asian countries.{{cn|date=March 2021}} [[File:Kumys-bottle.jpg|240px|thumb|A bottle and glass of [[Kumis]]]]

Milk products and their fermentation have had an important influence on some cultures' development. This is the case in [[Mongolia]], where people often practice a [[Pastoralism|pastoral form of agriculture]]. The milk that they produce and consume in these cultures is mainly [[mare milk]] and has a long tradition. But not every part or product of the fresh milk has the same meaning. For instance, the fattier part on the top, the "deež", is seen as the most valuable part and is therefore often used to honor guests.

Very important with often a traditional meaning as well are fermentation products of mare milk, like for example the slightly-alcoholic yogurt [[kumis]]. Consumption of these peaks during cultural festivities such as the [[Tsagaan Sar|Mongolian lunar new year]] (in spring). The time of this celebration is called the "white month", which indicates that milk products (called "white food" together with [[starch]]y vegetables, in comparison to meat products, called "black food") are a central part of this tradition. The purpose of these festivities is to "close" the past year – clean the house or the [[yurt]], honor the animals for having provided their food, and prepare everything for the coming summer season – to be ready to "open" the new year. Consuming white food in this festive context is a way to connect to the past and to a national identity, which is the [[Mongol Empire]] personified by [[Genghis Khan]]. During the time of this empire, the fermented mare milk was the drink to honor and thank warriors and leading persons, it was not meant for everybody. Although it eventually became a drink for normal people, it has kept its honorable meaning. Like many other traditions, this one feels the influence of [[globalization]]. Other products, like industrial [[yogurt]], coming mainly from China and western countries, have tended to replace it more and more, mainly in urban areas. However, in rural and poorer regions it is still of great importance.<ref name="mong">{{cite book| last1=Ruhlmann |first1=Sandrine |last2=Gardelle |first2=Linda |title=Les dessus et les dessous du lait. Sociologie et politique du lait et de ses dérivés en Mongolie. in Études mongoles et sibériennes, centrasiatiques et tibétaines, n° 43–44|year=2013 }}</ref>

Although this [[chemical process]] had been used in food production for thousand of years, microbial lactic acid fermentation was not properly described before much later. During the 19th century, several chemists discovered some fundamental concepts of [[organic chemistry]]. One of these was the French chemist [[Joseph Louis Gay-Lussac]], who was especially interested in fermentation processes, and he passed this fascination to one of his best students, [[Justus von Liebig]]. With a difference of some years, each of them described, together with colleagues, the [[chemical structure]] of the lactic acid [[molecule]] as we know it today. They had a purely chemical understanding of the fermentation process; it could not be observed using a [[microscope]], and could only be optimized by [[Catalysis|chemical catalyzers]]. In 1857, the French chemist [[Louis Pasteur]] first described [[lactic acid]] as the product of a microbial fermentation. During this time, he worked at the [[University of Lille]], where a local [[Distillation|distillery]] asked him for advice concerning some fermentation problems. Per chance and with the badly equipped laboratory he had at that time, he was able to discover that in this distillery, two fermentations were taking place, a lactic acid one and an [[Ethanol fermentation|alcoholic]] one, both induced by [[microorganisms]]. He then continued the research on these discoveries in Paris, where he also published his theories that presented a stable contradiction to the purely chemical version represented by Liebig and his followers. Even though Pasteur described some concepts that are still accepted today, Liebig refused to accept them. But even Pasteur himself wrote that he was "driven" to a completely new understanding of this chemical phenomenon. Although Pasteur didn't find every detail of this process, he still discovered the main mechanism of how microbial lactic acid fermentation works. He was the first to describe fermentation as a "form of life without air".<ref name="Past">{{cite book| last=Latour |first=Bruno |title=Les objets ont-ils une histoire? Rencontre de Pasteur et de Whitehead dans un bain d'acide lactique. in L'effet Whitehead, Vrin, Paris, pp.196–217 |year=1993 |isbn=978-2-7116-1216-1}}</ref><ref name="Hist">{{cite book| vauthors = Benninga H |title=A History of Lactic Acid Making: A Chapter in the History of Biotechnology, chapter 1 and 2 |year=1990 |publisher=Springer |isbn=978-0-7923-0625-2}}</ref>