I’m fond of cider, and I was curious what would happen if the “usual” cider fermentation process was augmented with a kombucha culture. I dropped a scoby into unpreserved apple cider to find out. On one hand, it seemed promising, since hard cider (fermented “naturally” or otherwise) tends to happen readily and has tasty results. On the other hand, I wasn’t adding anything with acid or alcohol to help ensure that the kombucha culture dominated the process. It would be possible to end with something disgusting, or even toxic.
For the most part, preservatives work by preventing microbial growth (preventing fermentation), so the use of preservatives was a concern for me. As far as I can tell, it’s rather hard to find cider that isn’t preserved in some way unless you’re willing to make it yourself, or can get it from someone who isn’t selling it commercially. There appears to be three different preservation procedures:
- Pasteurization: This kills most potential pathogens. While FoodSafety.Gov indicates that most juice in the US is pasteurized, I don’t think I’ve ever seen any that wasn’t. I suspect any found in a “normal” grocery store will be. While pasteurization kills microbes present at the time of pasteurization, it does nothing to prevent fermentation by microbes that later make their way into the juice.
- Acidification: In addition to pasteurization, most store-bought juices will be acidified. As with kombucha, the acidification acts to deter microbial growth, make it taste more refreshing, etc. Ascorbic acid is usually used for its antioxidant effect (oxidation would change the flavor and appearance), but malic acid (the acid prominent in green apples) is much stronger and may also be added. Since kombucha cultures are acid-tolerant, this shouldn’t prevent fermentation by the kombucha culture.
- Potassium Sorbate: This inhibits microorganism development, apparently by preventing reproduction. Since microorganisms tend to have a rather short lifespan but reproduce prolifically, this is pretty effective in killing off any preexisting microbes as well as any that later make their way into the juice. In fact, it’s added to many fermented beverages to halt fermentation and ensure that it does not restart later.
For my purpose, pasteurization probably reduces microbial complexity, but is probably useful for food-safety and consistency. Acidification probably won’t hurt, but it does color the results. Since it will start with a lower pH, it could inhibit the growth some of the early-phase kombucha microbes, and it would likely give the flavor more tang earlier than it would have otherwise developed. My previous experiment in starting acids showed that the specific acids will also have an effect on the final flavor. None of the acidification effects are bad, but things I’d that I’d rather avoid in this first experiment. It’s probably obvious that for fermentation experiments, potassium sorbate is right out.
I found a gallon of locally grown pasteurized apple cider from Curtis Orchard. It had no added anything, and was not made from reconstituted concentrate. I added a large scoby, but no kombucha or other acidfier to lower the pH. I thought about adding vodka to help make the environment a little more inhospitable to the non-kombucha cultures, but decided to run this experiment without that level of control (i.e. caution).
- 9 days: it is very frothy on top, so much that the thin scoby had gotten pushed up and was sticking to my paper filter (which is very wet). I replaced the filter and stirred the cider to get the cider-solids off of the bottom. The scoby looked kinda pocked, mirroring the large bubbles on which it was resting. It still tasted sweet like cider, but with more complexity. It had no sourness yet, which I suppose is reasonable since the pH didn’t register (> 4.4). I hadn’t really planned it this way, but it occurred to me that I might be able to bottle some of it the weekend before Thanksgiving as a sweet beverage, and the rest on or slightly after as a sour.
- 14 days: it tasted pretty much the same, but the pH was ~4.0. I discovered that my hot pad had been turned off, which undoubtedly slowed development. I turned on the hot pad and waited longer.
- 19 days: the pH was still ~4.0, but the flavor had developed. It reminded me of a Woodchuck hard cider (dark?) that I had 20 or so years ago. It also tastes a little “heady”, and I wonder if it had measurable alcohol. I passed some of this around at Thanksgiving, and it was well received by our guests. Even my kids said it was “not bad”. Not “good”, but this is still a relatively positive response for them.
- 22 days: the pH was 3.8.
- 26 days: the pH was 3.6. I no longer taste any sweetness, and I can detect some tartness in the bottom half of my 8 oz glass. It still tastes kinda heady.
- 28 days: the pH was still 3.6. On first taste, I think it’s a bit past it’s prime. A bit more sweetness would be nice. Adding apple juice doesn’t really help, but juice + malic acid does. It’s not nearly as interesting as it was from days 19-22, but it’s drinkable. There’s no longer any headiness to it. The scoby was relatively smooth on top, but pocked on the bottom and relatively thin and weak. It didn’t really develop after the first week or so.
On the day I bottled it, my middle child (who has perpetual digestive issues) asked if I had any more. I warned her that it no longer tasted quite the same, but she tried it. She thought it was horrible. However, since a part of my kombucha experimentation is to craft fermented beverages that my family will drink, this was still a major success! I’ve started the next batch. The variables are all the same, except that the hot pad was on when I started. I intend to check it every few days and bottle it when the pH is 4.0.
Depending on how this goes, for Batch 3 I may revisit the addition of acid at the beginning. When the cider reaches the desired level of sweetness, it may benefit from some tang, so some initial malic acid may be useful for “tuning” the sweet/sour balance. After that, maybe I’ll try a more commonly available apple juice (with malic and ascorbic acids) and see how that’s different from fermenting cider.