Alternatively, since this is about my third batch of scoby-free kombucha, you could call this part 3. The second batch was mentioned in my post on rooibos kombucha. Anyhow…
I bottled my third batch of scoby-free kombucha. After fermenting three weeks, it was approximately pH 3.2, tasted pretty sweet, and had little acetic flavor or scent. To 1 quart of kombucha I added 2.5 tbsp of ground dried elderberries, and the result tasted a lot like black currants with a touch of raisins. This was an interesting flavor, but I think it would have been better suited to a batch that was less sweet to begin with.
So far, it seems like my scoby-free experiment is getting gradually sweeter, fermenting more slowly, and producing a less vinegary flavor and aroma. The scoby it produces each time also seems to be a little less thick and more irregular in formation. It’s too early to tell if this is just a gradual process toward dying off, but the flavor and scent are heading in a direction that is more palatable to the rest of my family. Time will tell.
I read in interesting study titled Yeast Ecology of Kombucha Fermentation, which found that the scoby contained a higher concentration of yeast than the fermenting tea. Even more, it found that the concentrations were relatively stable in the scoby though the entire fermentation process. In the tea, some yeasts dominated the sugary beginning, and died off completely as the acidity increased. I’ve seen other studies (I’ll edit this post to link them if I see them again) that show the same thing for bacteria levels.
I took away two things from this:
- Scoby-free kombucha is likely to be the quickest way to gradually change the constitution of a culture. Some microbes won’t be transferred form one batch to the next, and any new introductions are likely to benefit form the decreased competition.
- However, because microbes that can’t tolerate a high-acids environment won’t survive from one batch to the next, you’ll only be successful in introducing microbes that are acidophilic, unless you make a fresh inoculation each batch. A scoby allows the survival of microbes form one batch to the next even if their environment otherwise becomes fatally hostile.
- From the perspective of kombucha as probiotic drink, scoby-free kombucha is probably not desirable, since it will, in time, contain a less diverse collection of species. (If it wasn’t for the fact that humans can’t digest cellulose, eating scoby would probably be the most effective way to get kombucha probiotics.)
- Scoby-free kombucha will probably produce a drink with different proportions of different acids. Aside from the easily identifiable acetic acid, my palate is not sensitive enough to tell what is present when mixed with such a wide variety of other substances.
- Kombucha brewed this way is probably sustainable, but may not be as vigorous. Fermentation will probably take longer to complete (and be less efficient) since it can’t benefit from the activity of microbes are best suited to each “stage” of the process.
I’m particularly interested in learning from the study of similar processes. For example, here’s an interesting study on bacterial fermentation, pointing out how the process for sauerkraut “has received substantial research in order to commercialise and standardise production. As a result, the process and the contributing micro-organisms are known intimately.” It mentions that a starter culture is recommended for addition to each batch to maintain consistency and accelerate the fermentation. It describes how, like kombucha, different bacteria dominate different stages of the fermentation. It goes on to describe how the use of latter-stage bacteria as the starter culture results in an incomplete fermentation and a substandard end product. It then speaks directly to the experiment of this post:
It is possible to use the juice from a previous kraut fermentation as a starter culture for subsequent fermentations. The efficacy of using old juice depends largely on the types of organisms present in the juice and its acidity. If the starter juice has an acidity of 0.3% or more, it results in a poor quality kraut. This is because the cocci which would normally initiate fermentation are suppressed by the high acidity, leaving the bacilli with sole responsibility for fermentation. If the starter juice has an acidity of 0.25% or less, the kraut produced is normal, but there do not appear to be any beneficial effects of adding this juice. Often, the use of old juice produces a sauerkraut which has a softer texture than normal.
There we have it. I’ll probably continue this experiment as long as it continues to develop, and as long as it seems to have potential as a relatively healthful drink for the familial acetophobes.