Mysteries of the SCOBY

Written by: Jonathan Percy Hall

Many of us are familiar with what kombucha is; it’s the result of introducing sweetened tea to a bacteria rich SCOBY and allowing the microbes within to ferment the dissolved sugars. This fermentation results in the iconic flavor, mouthfeel, and nutrient composition that makes kombucha so widely loved. But what is SCOBY and how does it transform tea into kombucha?

SCOBY is short for symbiotic culture of bacterium and yeast. This symbiotic community can contain a wide array of microbial flora, but they most commonly contain bacteria like Gluconobacter and Acetobacter and yeasts like Zygosaccharomyces, Saccharomyces, and Schizosaccharomyces species. This diverse community is held together within a cellulose matrix which forms the iconic disc within the fermentation container.

During the fermentation process, the yeasts take in the disaccharide sucrose and break it down into the monosaccharide’s glucose and fructose. This simple sugar is then converted by the yeast to ethanol and carbon dioxide which helps to create the desirable effervescent mouthfeel. The bacterial species then use the ethanol to create various organic acids. Most notably acetic acid, which you may know as vinegar. If left to their own devices, the SCOBY will produce high amounts of acetic acid, which results in a very tangy booch.

Other metabolites, vitamins, and minerals can also be found in kombucha as a result of the specific microbial populations and their unique metabolic pathways. For example, lactic acid producing bacteria are responsible for the presence of vitamin b12.

It is important to remember that this is just the basic overview of how the SCOBY works and that the final characteristics of the kombucha depend greatly on the age and composition of the SCOBY. Even though there are so many differences between SCOBY, the one thing they all have in common is that they are self-perpetuating communities full of hard-working microbes that can make a delicious batch of kombucha.

Information gathered from

Recent Progress in Chemical Composition, Production, and Pharmaceutical Effects of Kombucha Beverage: A Complementary and Alternative Medicine. (Mousavi et al)

MICROBIAL DIVERSITY OF THE SYMBIOTIC COLONY OF BACTERIA AND YEAST (SCOBY) AND ITS IMPACT ON THE ORGANOLEPTIC PROPERTIES OF KOMBUCHA (Danielle St-Pierre)