According to the literature, human taste sensation of sourness not only depends on [acidity] but is also influenced by the shape of the molecules in question. Vinegar tastes considerably more sour than lactic acid with the same pH.
It has been suggested that one could cover the brewing container with a plate if a reduction in sour taste was desired. This would cause more lactic and less acetic acid to be produced. My experiment seemed to confirm this as far as flavor was concerned.
This is essentially what I did. One of my brewing vessels is a candy jar, with a heavy glass lid that rests on top. I used a double-layer of coffee filter between the two pieces to help fill any glass irregularities and keep out bugs, but it was relatively sealed except the two or three times I drew samples for tasting. The pH of this batch was ~3 at bottling, when it tasted done when I sampled by straw-dropper.
I reserved one pint plain, and flavored 1 quart each with a bag of Lemon Lime Zest and Peach Paradise (by London Fruit & Herb). The remaining pint-plus was mixed with the pint from my oolong KT and became the starter for a scoby hotel. The flavor was relatively mild, but much more complex and interesting than the oolong kombucha. Unlike the oolong kombucha, I couldn’t really taste “tea”. I typically rotate though each of my quart jars, pouring drinks from a different one each day, so that each has a chance to age and to extract more flavor from the bag with which it’s being flavored. The kombucha flavors have been deepening, perhaps due to the increased oxygenation during bottling and with each pour. I keep it refrigerated, so i don’t think there’s much fermentation happening, but something is happening.
The lemon-lime isn’t particularly interesting. It’s agreeable enough, and will probably be good for the girls. It’s like the plain mixed with Sprite. For me, one of the attractions of Sprite is the clean, simple flavor, and this combination doesn’t do much for me. The peach is nice, and it’s good to see that a different brand of peach tea works as well as the one used previously. It’s not all that interesting of a flavor, but it forms a pleasant, coherent gestalt.
I noticed two additional tidbits from that article. First is that the anaerobic version produced no scoby (zoogloea). My anaerobic kombucha produced a scoby, so perhaps I somehow had airflow, or “excessive” oxygen in the jar? The second tidbit is that the experiment added starter culture, BUT NO SCOBY. This suggests that is should be possible to brew Kombucha without transferring scobys for one batch to the next. This would seem to be consistent with the way that people used to have a lot of success starting Kombucha from unpasteurized bottles of commercially-available Kombucha. I’ll have to add that experiment (transferring starter, sans scoby) to my list…