Not souring - from yeast interactions?

I made a sour in March and took a sample to check it's progress (5 months old). It is not sour at all.

While not purely scientific with only one variable, I have another (8-month old) sour using the same brett yeast strain which has had a nice tart flavor since it was 3-months old. The major difference between the two beers is that I added some wild yeast harvested from grapes in my backyard. So, I suspect the lack of souring has to do with this additional yeast. Here are the details:

OG: 1.070
SG: 1.020 (at 5 months old)

Malt bill: Without getting into details, it's like a dubbel. No oak, cherries, or anything fancy yet...

Yeast: Wyeast 3787 with starter, then pitched WLP 650 Brett Brux after about a week, then pitched wild yeast harvested from grapes in my backyard. I pitched what (visually) appeared to be the same amount of yeast as the WLP 650.

Aroma: Anytime I sniffed the airlock throughout fermentation, I got good Belgian aromas - banana, clove, etc. Never had any signs of something off.

Taste: Tastes like a dubbel, tasting the 3787 mostly. I also have some slight off flavors that are medicinal/solventy. I think the off-flavors are from the wild yeast but I need to read up more on it, I could be wrong.


Does anyone know if different yeast strains can suppress each other or otherwise have negative interactions? Why haven't the brett gotten to work like they have in my other beer, which was getting sour after 3 months? Do I just need to be patient (is this just the sour-version of a n00b yeast question)? Thanks for any advice or stories from similar experiences.

Did you pitch any lactic acid bacteria? Some brett strains can be a little tart, but unless you have lacto or pedio in there, it won't get sour.

Yeast interactions will not suppress sourness directly. Alcohol will inhibit lacto, as will hops. But sacch yeast plus brett will not sour by itself. Do you have access to jolly pumpkin dregs? At this point your best bet might be to pitch some bottle dregs containing lacto and pedio, and hope for the best.

what agate said: brett does not make sourness, and you should add some commercial dregs. maybe grow them up a little by pitching them in a cup or two of weak wort (1.020) and given them a few weeks to regain their strength before throwing them back into battle. have a sour beer party, crack open a few bottles and save all the dregs.

you could also pitch some commercial pedio. at this point commercial lacto probably won't do much, IMO.

The other thing I'd be tempted to try is to boil a gallon of extract 1.040 wort, throw some commercial lacto (think omega labs' lacto) in there, and let the gallon get as sour as possible. Then blend it into the rest of the batch and let it ferment out with the sacch/brett. It won't be puckering sour after blending, but it might get you close enough.

Thanks for the feedback. It's easy enough to buy some Jolly Pumpkin and add it in! I have no problem doing that.

I'm using WLP650. I didn't think it would sour after reading up on it (i.e. no lacto or pedio) http://www.whitelabs.com/yeast/wlp650-brettanomyces-bruxellensis That's part of why I threw the backyard wild yeast from the grapes into the beer - thought that might make it sour or at least interesting, but I don't really detect much aroma from it.

What has me confused is that I've made two beers with WLP650 and one soured and one did not. I'm wondering if the sour one is technically infected, but it seems unlikely that the perfect strain of wild yeast would have gotten into it to make it taste nice.

Brettanomyces will produce acetic acid if exposed to too much oxygen - could you have some low-level acetic acid in the first beer causing it to taste tart?

I've cultured yeast from my backyard grapes as well. The first two times, it stopped at about 1.7%ABV. The third time it was fed, though, it went from 1.040 to 0.997. So there might be some interesting yeasts and bacteria on them - just might take a long time for them to have an effect. There's a decent chance, though, that pitching them into an alcoholic environment killed them.

Thanks, Agate.

I didn't think of this at first, but another "big" difference between the two beers is the fermentation vessel. The sour one is in a 5-gal plastic bucket and the other is in a better bottle plastic carboy. The plastic bucket is probably letting more oxygen into the beer. That said, the level of acetic acid is pleasantly tart and not harsh, at least to me anyway.

I've read so much about which vessel is best but haven't seen anything conclusive. This seems to be a helpful, firsthand lesson!

In addition to the fermentation vessel changes, lack of pedio/lacto, add bottle dregs as others have noted above are all good points and probably should still be done (the dregs or omega labs).

My statement is based on no science and just personal experience. When I have beers that are to tart for my enjoyment and close to fg (<1.006) I will usually back sweeten them a bit and it really helps mellow/smooth the tartness. I usually don't take a measurement and just back sweeten 'to taste'. I wonder how high my gravity gets on the back sweeten.

Thus my question, could 1.020 be pretty sweet and hiding any perceived tartness? Was his previous experience with brett at a much lower fg?