This 1 quart experiment was started early March, and ran for 6 weeks. At the time I wrote:
This is a quart of “normal” kombucha except that the white sugar has been replaced with xylitol. I’ve read that xylitol doesn’t work in kombucha, so this has the same expected minimal fermentation as the sugar-free kombucha, except sweetened by all of the starting unfermentable xylitol. In other words, I may end up with plain sweet tea. However, there are a few yeast or bacteria that can use the xylitol, and perhaps some are in my culture. We’ll see!
Here are the results:
- At 2 weeks, the pH was 4.4 and the flavor was sweet. It had a very thin (1 mm) scoby that sank to the bottom.
- At 4 weeks, the pH was 3.6 and the flavor was not sweet, but lightly sour. It appears that a thin (1 mm) scoby formed in the bottom, as a very even line “floating” above the one that sank at 2 weeks. This seems very strange; maybe it had been floating, and sank when I moved it?
- At 6 weeks, the pH was 4.0 and the flavor was very watery, with a very slight tea flavor, but no sweetness or sourness. A thin (again 1 mm) scoby floated on the top. Approximately 1 inch of liquid has evaporated.
At this point, Since there wasn’t really any forward development between weeks 4 and 6, I decided to stop this experiment and dump it out. Despite the apparent likelihood that nothing would happen and I’d end up with nothing more than xylitol-sweetened tea, the culture seems to have been able to consume the xylitol to produce acid. Apparently when that was done, it consumed the acid that it was a byproduct of it’s earlier fermentation. This study describes how acetic acid bacteria not only metabolize xylose (is that relevant to my apparent oxidation of xylitol?) but also the metabolization of acetic and other organic acids (search for “overoxidation”).
So while this was an interesting experiment, it didn’t really suggest a future path for producing easily-drinkable kombucha. I’ll move on…