I mentioned a previous post that cinnamon is antimicrobial, so I decided to see if it would prevent kombucha fermentation. I added two cinnamon sticks (one very thick, one very thin and coiled) to an otherwise normal 1 quart micro-batch of kombucha.
- Day 7: pH is 3.6, but it tasted sweet and strongly of cinnamon without any discernable sourness. The scoby seemed very thin and patchy, without covering the entire surface, but inserting a straw to take a sample showed that it was a single solid piece that was very flexible and durable. Perhaps the appearance was due to cinnamon oil on the surface? It looked a little darker than I’d expect, but it was also rather clear and not at all cloudy.
- Day 14: pH is 3.6, but it still tasted sweet, cinnamony, and not at all sour. Since it didn’t seem to have developed, I postulated that the cinnamon killed or stunted the yeast/bacteria.
- Day 23: pH 3.6. It was still sweet, cinnamony, and not at all sour. It didn’t taste bad, but it didn’t seem to be progressing. I started brainstorming ideas on how to kickstart it if there was not progress after another week.
- Day 28: pH 3.6. No progress was noted, so I added 1/4 tsp Yeast Nutrient (DAP + urea) and 1/4 tsp inulin to see if this would restart the fermentation. I’ve found that each of these is capable of providing the nutrients kombucha needs to ferment. Unsurprisingly, the scoby sank when I stirred in the additional nutrients.
- Day 36: pH 3.2. Despite the pH drop, It was still sweet, cinnamony, and not at all sour. A new scoby was forming, very thin, but very tough and pliable (rubbery). The scoby looked like it might be clear, but it was hard to tell when it was floating in the dark kombucha. With the drop in pH but no detectable sourness, it seems likely that it produced an acid other than acetic. I decided that while I probably could drink it like that, but I’d let it keep going to see what happened.
- Day 42: pH 3.2. Despite no change in pH a light sourness developed in addition to the sweet cinnamon flavor. The scoby was a bit thicker.
- Day 49: pH 3.2. No change from last time. I added a small scoby to see if fresh microbes would make any difference.
- Day 56: pH 3.2. There was more scoby than last time. Some unpleasant solvent-like flavors appeared, which might have obscured the cinnamon flavors, which had become less noticeable. I decided it was time to end this experiment.
The development of off-flavors at the end made me wonder what sort of changes were happening. The low pH makes for a pretty hostile environment for most microbes, and the evident antimicrobial effect of the cinnamon only make it even more inhospitable. Maybe it would have developed in some interesting way if I would have let it go even longer, as its common for some beer off-flavors to resolve over time when brettanomyces or other “wild” yeast are involved. Nevertheless, I think 8 weeks is long enough to exceed the patience of most kombucha brewers.
I had two takeaways from this experiment. The first is to make sure that you don’t add cinnamon to your kombucha fermentation! :) The second is to reconsider flavoring your brewed kombucha with anything that includes cinnamon if you drink kombucha for the general probiotic effects common to fermented foods.