Is Fermentation Biology or Chemistry?

Fermentation is driven by living microbes, but chemistry shapes what they do and what gets produced.

• Fermentation
• Biology
• Chemistry

Short answer: both.

This article could easily go deep into why fermentation is biology or chemistry (or both), but to keep it short, I’ll give only an example or two of each.

First, fermentation is biology because it’s a process by which bacteria and yeast consume sugars and convert them, as well as some flavor compounds (see biotransformation) into alcohol, vinegar, acids, etc. and other new flavor compounds.

However, it’s also chemistry because a variety of environmental factors can be tweaked to influence which microbes are most active and in what ways they process the molecules present. These include temperature, the pH (acidity) of the liquid being fermented, and even the presence or absense of specific ions, salts, enzymes (though technically enzymes might be biology), and more.

Furthermore, the chemicals produced as a result of fermentation can cause secondary reactions of a primarily chemistry-oriented nature. For instance, when making cheese, the initial culture feeds on the lactose to create lactic acid, which then interacts with the proteins in the milk, causing them to bond together to create the curd structure.

With all that in mind, is fermentation biology or chemistry? Fermentation itself is a primarily biological process. However, the chemistry has a clear and direct impact on this biological process.