As a followup to my third batch of kombucha cider, I used a kombucha culture to ferment common inexpensive apple juice. It contained water, apple juice concentrate, and ascorbic acid, and I added a scoby. The starting pH was >4.4.
Here’s what happened:
- Day 3: A thin scoby was forming, though I never really saw this with the cider. I’m guessing it was because the cider fermentation was so vigorous that there were constant CO2 bubbles, interfering with pellicle formation on the surface.
- Day 13: pH 3.6. It was still very sweet, but also noticeably sour. There wasn’t any sense of headiness like I had with the cider. I pulled off some of this and mixed it with the last of the over-fermented cider batch 1 in a 3:1 ratio. Girl 2 said “it’s good”, the other two thought it was “okay”. The scoby was thin, irregular, and fragile. I could totally believe that a profusion of CO2 bubbles would tear it up, resulting in the sort of “scum” that I saw with cider 3.
- Day 15: No pH reading. It seemed slightly less sweet, but still not ready.
- Day 17: pH 3.6. Although the pH didn’t appear to have changed, it definitely tasted more sour and less sweet. It seemed to have a mouthfeel with a thicker body than usual.
- Day 20: pH 3.4. I bottled it at this point.
When refrigerated, this is definitely sweet and definitely tart. Not as good as cider 2, but it’s definitely drinkable. It reminds me of drinking pineapple juice.
I think the bacteria’s acid production got too far ahead of the yeast’s sugar consumption. Or it could also be that apple juice has more sugar and acid compared to the cider (which did not have any acid added as a preservative). Next time I may add tannin in some form, since that seemed to speed up the sugar consumption. I wouldn’t be surprised if the apple juice was low on tannins, anyway.