Using chlorine dioxide to select yeasts in a kombucha culture

[hotwatermusic]

I would like to try using chloride dioxide to kill bacteria in finished kombucha. My hope is that i can then pitch the remaining kombucha into a starter and build up just the wild yeast and eventually try fermenting either beer or cider with it. I love the level of funk my kombucha has.
Has anyone tried anything along these lines? I've perused other threads about washing slurries and would probably attempt something along those lines.
20-40 ppm in a 300ml sample to start.

 

[Andrew Hodgson]

This is a cool idea, I am interested if anyone has tried something similar. My first thought is that disturbing the balance of yeast/bacteria in the booch will certainly change how the final product tastes?

I was mulling around an idea like this but I was going to just chuck the SCOBY right into some wort and seeing what happened.

 

[hotwatermusic]

I finally got around to trying it. Results are all negative. No activity after 4 days. At this point if something kicked off i think it would just as likely be a wild bug that crept in do to imperfect sanitary process. Used 300ml of fresh raw kombucha to inoculate around 700ml of canned starter wort.
I assume either the chlorine dioxide was harmful to the yeast or that yeast which has subsided in a solution of tea with simple sugar for generations just can't ferment the longer chains in barley based wort?
At any rate if anything else happens I'll report back. It's all spare equipment so i might as well wait a while longer...
There is possibly some off-gassing but I'm still doubtful.

 

[hotwatermusic]

Should have kept my mouth shut. A day later there are, let's say, visible changes? Don't know what it is but it doesn't seem to be off gassing...
Don't know what'sgoing on but i can't upload pics. Sorry.

 

[hotwatermusic]

Should have kept my mouth shut. A day later there are, let's say, visible changes? Don't know what it is but it doesn't seem to be off gassing...
Don't know what'sgoing on but i can't upload pics. Sorry.

Ok...pics from today and yesterday.

 

[hotwatermusic]

And now...

 

[hotwatermusic]

To put a bow on this thing for anyone who comes across the thread, I finally have a beer from it. Ended up co-pitching with T-58 because the fermentation with only kombucha yeasts were slow to start and didn't seem to attenuate well. I was afraid those cultures have become used to a simple sugar environment & wouldn't make a great beer alone.
I brewed a malty Belgian-ish beer close to a bier de mars maybe. The final product is disappointing. Great brett aromatics followed by an unimpressive apple like ester. Mostly clean mid palette. Some slick ness with a twang in the after taste. Not a fan. Dumped the slurry.

 

[RPh_Guy]

Thanks for reporting back!

Sorry I didn't see this earlier. I could have helped. Chloride dioxide is broad-spectrum, so it won't select yeast, and only damages the culture.

Suggestions if anyone wants to make beer with a kombucha SCOBY:

• Build a ~1.040 wort starter with the SCOBY like you would with any other liquid yeast. Add hops if you don't want it sour (hops inhibit the lactic acid bacteria).
• Kombucha primary yeast may only attenuate wort 25-50%, so you need to make a decision -- you can let the starter go a long enough time to try to increase the Brettanomyces count enough to do the primary fermentation (at least a couple weeks; maybe step it up every few weeks until you get a good attenuation; Brett is slow), or pitch beer yeast to finish fermentation (I would suggest you add the commercial yeast after letting the SCOBY ferment for a couple days). Again, use hops if you don't want it to sour.
• Protecting the beer from oxygen prevents acetic acid (vinegar) production, however there may be a little tang from the aerobic starter.
• Aging at least a few months is recommended to allow Brett expression and to allow it to clean up off-flavors, as well as make sure full attenuation has been reached.
• Add any flavorings close to packaging.
• Consider an acid shock starter if bottling, to prevent THP.

Cheers

 

[hotwatermusic]

Great suggestions thanks for the comment. If chlorine dioxide truly is broad spectrum I'm surprised I got anything out of this. It was done on a lark and probably as good as could be expected. Your ideas might just inspire me to try it again some time. I feel like overall it was a decent expression of kombucha, good and bad. Never got truly sour although I imagine there was some production of organic acids that produced that twang I mentioned. I have a three gal keg of the stuff that will probably get dumped when something better needs a home and one 24oz that was bottle conditioned. I'll let it sit a year or four and pull it out someday to see if brett saves the day like it always seems to.

 

[RPh_Guy]

If chlorine dioxide truly is broad spectrum I'm surprised I got anything out of this.

As with any anti-microbial, the activity depends on the concentration. It may have outright killed only some of the microbes but just inhibited/weakened others.

Never got truly sour

What was the hopping rate & IBU?
Hops inhibit the lactic acid bacteria.

Your ideas might just inspire me to try it again some time

You also have the option to ferment a beer with the normal beer yeast of your choice, and then add the kombucha SCOBY after primary. This would allow only the Brett to add flavor, but sort of removes the novelty of allowing the SCOBY to eat most of the sugar. This method should avoid the cidery taste.

Yet another option is blending kombucha with beer. This gives more control, especially since you keg and can keep it cold to prevent additional fermentation.

Cheers

 

[logos]

The best way might be to streak it out on an agar plate and then grow up just one colony into a starter. Potato dextrose agar and malt extract agar are both pretty easy to make and available cheapish to buy online. To select for yeast (kill the bacteria) could add an antibiotic or drop the pH.

 

[RPh_Guy]

The flavor of kombucha comes from the whole mix of microbes, so I think isolating one strain might be counterproductive.

 

[Miraculix]

This is very interesting! I didn't know that kombucha includes brett.... But it obviously makes perfect sense.