Brett Dregs - Starter. What did I do wrong?

[sancycling]

Hi all,
I did my first attempt to grow the dregs from several brett beers that I liked. Here is my process. What did I do wrong?

1) Made a 1.5lt starter, 1.040 OG with DME, 1tspn of yeast nutrient and fermcap. Boiled, cooled ~65F and added the dregs from three or four bottles.
2) I left the starter for about two weeks on a stir plate just covered with sanitized foil. Room temp ~70F
3) stopped the stir plate for a couple of days, all the Brett settled in the bottom.
* Until this point everything seemed to be going great. I got slow but active fermentation for several days, the smell was nice.

4) I wanted to step up the starter a second time. So I did the same process, decanted the first satarter and dumped it into fresh wort.
* I tasted the sample and I thought it was fine, of course very thin and not much flavor with no hops but a clear brett character.
5) I left it for another two weeks in the stir plate to promote growth again only covered with foil.
6) stopped the stir plate to be able to decant the wort.
*After a few days a very pretty white pelicle was covering the wort. The smell was of acetone pure strong acetone. I tried a sample and it was horrible, I've never tasted nail polish remover but I'm sure that's how it tastes. So I dumped it!!!

NOTE: I'm very cautios with sanitization. Everything that touched the wort after boiling was very well sanitized with starsan.

So what happened? Too much oxygen? Should I have used an airlock? Any ideas?

Thx

 

[BrewDawg79]

I'm no expert but my understanding is that brett can produce acetic acid when exposed to oxygen, which is what the stir plate was surely doing. This isn't necessarily bad for a starter as you would have probably decanted the end result prior to stepping up again or pitching into wort/beer. Give it another shot if you can. FWIW, I typically start with a lower gravity and lower volume first step for dregs prior to stepping up. Haven't had any issues with that. Good luck.

 

[Aristotelian]

My understanding is that brett may clean up other compounds but it can take a while. I would let it ride for a while next time and see if the aroma clears up.

I made a starter from saison dregs that had a strong acetone/jet fuel aroma while actively fermenting but it cleaned up fine.

 

[jfolks]

What did you do wrong? You dumped it!

As others said - this is a consequence of the oxygenation via the stir plate. While experiments have shown that increased levels of oxygen decreases the time to achieve maximum cell density, it can have the side effect of increasing acetic acid production.

Next time just let it ride, flocculate, then decant and you will be fine (regardless of nail polish remover flavors in the starter 'beer') (note: Chad at Crooked Stave found that refrigerating brett cultures caused them to die eventually, so play it safe and let it flocculate at room temp over a couple weeks if you plan to decant)

 

[sancycling]

Should I not use a stir plate?

 

[jfolks]

If you want more/quicker cells, then use a stir plate. If you want to minimize/mitigate acetic acid production, then don't (Chad at Crooked Stave recommends no stir plate, swirling occasionally by hand - letting it go for a week or so).

 

[sancycling]

Cool. Thanks for the input... Now it's time to start buying and drinking some good brett beers and utilize all this knowledge.
Cheers

 

[BrewDawg79]

Now it's time to start buying and drinking some good brett beers...

One of my favorite parts, for sure.

 

[worlddivides]

Now it's time to start buying and drinking some good brett beers...

One of my favorite parts, for sure.

Couldn't agree more. Been buying a lot of 100% Brett fermented beers lately, and they are pretty damn awesome. Almanac has been one of the brands I've been buying a lot of Brett beers from.

 

[505-Brewer]

Nail Polish is not acetic acid buy typically ethyl acetate. Could be something was off. While a starter might not be optimal (yeast energizer infused beer is not tasty) it shouldn't be that offensive. I would start w some brett cultures from a lab and progress from there. Could be something was up with the bottle source.

And yes 1.5 L is way to big to start. 200mL of 1.020-1.040 would have been better. Why stress the stressed.

 

[Agate]

True, but acetic acid is a precursor to ethyl acetate, which brett can create from acetic acid and ethanol.

 

[secondbase]

Sounds like too much oxygen to me. I may have missed it, but what were the brett beers? Is it possible that there was more than just brett in these? Lacto can create ethyl acetate in the presence of oxygen. For that reason, you do not want to put mixed cultures on a stir plate.

 

[505-Brewer]

True, but acetic acid is a precursor to ethyl acetate, which brett can create from acetic acid and ethanol.

Yes. Thank you for that. Could be it. Decant and do a step w airlock. That should be clean.

 

[nthammer]

I used an airlock when I stepped up bottle dregs and didn't have any issues. And like others have said, my first starters volume was smaller and I believe lower gravity as well

 

[sweetcell]

Should I not use a stir plate?

you'll get more cell growth, but some off-flavors, if you use a stir plate on an all-brett starter. so, your call: as long as you're OK decanting, a stir plate is fine. i like to use a stir plate on low for a day or two then turn it off.

interesting read about brett starters and aeration: http://www.milkthefunk.com/wiki/Brettanomyces_Propagation_Experiment

but this was a single experiment, which leads us to the problem of:

(Chad at Crooked Stave recommends no stir plate, swirling occasionally by hand - letting it go for a week or so).

the problem with any advice on growing up brett is that there is so much we don't know about that the genus. from the above link:

"It has been suggested by MTF member and microbiologist Richard Preiss that propagation times vary widely among Brettanomyces strains, and that the selected strain most likely exhibits faster reproduction than other strains [3]. Additionally, Trent's experiment did not demonstrate the same "second lag phase" as shown in Chad Yakobson's "The Brettanomyces Project" [2], including for the lower cell count treatment in the second experiment. (...) Preiss also notes that not all strains of Brettanomyces exhibit the "second lag phase", and that the chosen Brettanomyces strain may be one of these strains."

my reading of this is that it can be misleading to draw conclusions about all brett strains. we tend to use "brett" as if it is a single yeast, or at least very similar yeasts. they're not.

(note: Chad at Crooked Stave found that refrigerating brett cultures caused them to die eventually, so play it safe and let it flocculate at room temp over a couple weeks if you plan to decant)

at least one set of experiments contradict this assertion. over a month, brett stored in the fridge had much higher survival rates than brett stored at room temperature. perhaps something different happens for longer time periods, TBD, but i've switched to storing in the fridge. chad never provided any data (or even details) on what led him to conclude that warm storage was better.

the above experiments were done with 4 different brett strains... perhaps the one(s) that chad uses behaves differently.

 

[jfolks]

All good points, sweetcell.

Brett strains are the ultimate "YMMV" beer ingredient!