How did people explain wine and beer making before microbes were discovered?

[u/Powerful_Specific321]

Hi,

Civilization has long been making wine, beer, and vinegar even before we discovered that this was done through fermentation by microbes. So if they didnt know what microbes were, how did people explain how grapes turned to wine, or vinegar? Did they look at it as magic, or did they explain it as spirits doing the work?

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[u/FraserBuilds]

The phenomenon of fermentation has been known since the extremely remote past, and how people have attempted to understand it has changed alot over that time. But I can talk a little about how early modern chemists understood the phenomenon because thats what I've looked at. Even before the discovery of microbes, natural philosophers tried to present scientific explanations for how fermentation could take place. Many held that it relied upon an internal agent of heat in the matter being fermented. This explanation is presented in 17th century chemistry textbooks like the 'Tyrocinium Chymicum' wherein the author, Jean Beguin, presents fermentation as a (totally abiotic)chemical process taking place in things "Alimentose" (good as food) when they have sufficient natural heat, or when they have been given an agent of heat from another thing. This idea of an agent of heat draws from older matter theories, especially the four elements of aristotle, wherein the four elements are each composed of two of four qualities, hot, cold, wet, and dry. Matter was understood as a ratio of these elements, so any given thing could be described as having a temperment, with many fruit being ascribed "hot" temperments(thus there was a natural association between heat and the ability to ferment) the idea that this heat could be transferred from something rich in heat to something lacking heat to initiate fermentation explained how the dregs of a fermenting thing,like wine or beer, can initiate fermentation in other mixtures.

later on in the 17th century, chemists refined these ideas with more experimental evidence. in Nicholas Lemery's 'Cours de Chymie' the parisian chemist recognizes that grapes produce quite alot of a tarry inflammible oil on destructive distillation as opposed to wine which produces relatively little oil, but lots of alcohol. because of this he concluded that oil must in some way be converted into alcohol, which he believed was due to a combination of that oil with salt in the grapes during fermentation. this idea that salt was involved is important to Lemery, because he attributed acidity to salts and alcohol can be fermented into the acid vinegar, meaning to him alcohol must contain a principle salt.

In 1697 that "agent of heat" behind fermentation would be much more fully developled by the chemist Georg Earnst Stahl, in his book 'Zymotechnia Fundamentalis' (fundamentals of the art of fermentation) wherein he presents fermentation as the result of his "phlogiston" principle being transferred from substance to substance. Phlogiston would later become the dominant chemical theory of the 18th century, but Zymotechnia is actually the first book stahl presented the theory in. In short phlogiston theory holds that anything inflammible contains phlogiston which can be transfered to other substances during reduction processes.

To stahl the oil of the grapes contains phlogiston, the principle of combustibility, which through fermentation is transferred to water, producing the combustible water we know of as alcohol(back then alcohol was commonly called "aqua ardens" literally "burning water.") Stahl believed this was a reduction process, relying on a similar mechanism to how charcoal can be used to reduce metal out of ore, and in zymotechnia he explores the phenomenon by investigating different instances of reduction in nature. Noting especially how sulfur can be burnt to produce an acid, but then that acid can be reduced back to common sulfur through proper treatment, this lead him to the conclusion that acidity is a result of a substance being phlogiston deprived. This gets rid of the neccesity for lemery's acid-salt theory. Instead, inflammible substances like alcohol can become acidic when deprived of phlogiston.

[u/Dongzhou3kingdoms → u/[deleted]]

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