All day long we tell people that kombucha is a “fermented tea,” but what does that really mean? I ask this question because there are a lot of assumptions that are made when the word “fermented” is used.
In reality, while kombucha is definitely a fermented beverage, it’s not only a fermented beverage. There are various other biological activities that take place inside your humble brew vessel.
But when it comes down to it, regarding fermentation, most people want to know two things: the alcohol content and the amount of sugar in kombucha. These two facets of the drink are intertwined. In fermentation, the higher the initial (pre-fermentation) sugar content, the greater the potential for alcohol content. Fermentation is responsible for turning kombucha from super-sweet tea into the slightly sour, low-sugar beverage we all love - that’s because there are micro-organisms at work consuming and converting those initial sugars, among other things. That’s why your brew will become more acidic and less sweet as it progresses.
Not only that, but every brew is different, and some of the various reasons why this is true would be laborious to measure. ‘Buch fermented on the East coast will be different than one fermented on the West coast, in different homes of the same city, etc., based on subtle differences - the spontaneous contributions of “wild yeasts” that will come into contact with your brew during preparation, pouring, or transference, variations in temperature, minute differences in microbe population of your SCOBY or starter, and the many qualities of the nutrient (or “nute,” the sweet tea that becomes kombucha). Those are just a handful, but it’s easy to consider even more - temperature, atmospheric pressure, available oxygen in your brewing area, ventilation, interrupted respiration from moving the vessel, proximity to magnetism, playing Mozart to your brew, and many others.
When it comes down to it, considerations of sugar and alcohol in kombucha, while correlated, are still based on a number of other variables. This also makes it difficult to come to an across-the-board average on caloric content in kombucha when it’s not produced in absolutely consistent conditions, such as in a brewery or laboratory. But don’t let these considerations scare you away from brewing, it’s still as simple as ever.
In subsequent blogs, I’ll flesh out more of the intricacies of sugar metabolism and inversion during kombucha production. In the meantime, throw back a homebrew, and consider becoming your own ‘buch researcher, and of course be sure to let us know what you find (easy to do with our ‘Buch Brewers’ Group on Facebook).