A little science on basic beverage fermentation will help us get a handle on the seemingly mysterious world of bacteria and yeasts that transform sweet liquids into fizzy, tangy, healthier beverages. By understanding a little more about what’s happening in the microcosm inside your bubbling jars and bottles, you will become a better problem solver and, therefore, a more adventurous and confident brewer. While I slept through much of my chemistry class in school, when I became fascinated with the applied science of food and beverage fermentation, suddenly my interest in science was piqued. In culinary school, during salad dressings class, we were doing a vinegar tasting. An innocuous question sparked my quest to understand more about microbes: “But where does vinegar come from? How is it made?” My question stumped the instructor. “Well, err, it is just wine, or apple juice that is left out and goes sour . . .?” So my query left me sifting through chemistry formulas, starting with carbohydrates and ending up with acids.
But how? Who or what was responsible for the conversion of sugar to vinegar? The next step led me from chemistry to biology books, learning about yeast and bacterial fermentation. I am by no measure a food scientist, but getting a handle on the basic science of fermentation in food and drinks helped me understand food safety, troubleshoot a gushing or burst bottle, a soda that didn’t fizz, and get to the bottom of why one batch went differently than planned while the next was tasty. I appreciate this straightforward definition of fermentation by Sandor Katz, author of Wild Fermentation and The Art of Fermentation: “Fermentation = the transformative action of micro-organisms.” .