Gose / lacto WTF moments?

[bwarbiany]

Okay, so I'm brewing the Gose... Plan was to sour the wort post-mash using a lacto culture. So I collected my wort, hit a gravity [pre-boil] dead on the nose at 9.2 Brix / 1.035 SG.

Pitch the lacto, let it sit about 30 hours, and toss it back on the burner. I pulled a sample with the thief before the temp started climbing.

Now my hydrometer reads 1.004*, and my refractometer reads about 4 Brix (1.016 SG).

I find this very confusing. I'm using Lactobacillus delbruckii, which I understand can't create alcohol (only lactic acid). And lactic acid supposedly has a specific gravity (depending where you look online) of 1.050 or 1.200, so while I can buy that it would completely throw off the refractive index on the refractometer, I see no way that it could have dropped the hydro reading to 1.004.

I'll update once I complete the boil, which was expected to get to 1.044, but wondering if anyone has an idea what to make of these numbers?

(* Sample was not temp-corrected or degassed. Temp was probably in the mid-high 70s of that sample, but that's not enough of a difference to account for the crasy numbers. Could it be the gas created by the lactobacillus?)

[bwarbiany]

Even stranger now that I dig into it... One thing I didn't do with the wort was to bring it up to pasteurization temps prior to cooling it and pitching the lacto. It went into the kettle at about 140, was chilled and the lacto pitched. So I conceivably could have something other than the pure lacto in there.

With a starting OG of 1.035, Beersmith's refractometer tool says that 4.00 Brix results in...

1.004 SG.

And I noticed that the boil started at about 200 degrees, which I thought was odd.

Did something in this wort ferment down the entire batch to 1.004??? And it boiled off so quickly because it had plenty of alcohol?

I find it amazing to contemplate that it could have all fermented down that quickly, even at the ~90 degrees temp I saw. And it didn't pick up any crazy flavors either -- I got a very light tartness, not the sort of intense sour I would have expected if something like pedio got in there.

WTF? I'm contemplating now whether I should be adding DME and/or sugar to the boil or just ditch this entire batch??

[bwarbiany]

During the boil, I added some sugar and DME, and my post-boil refractometer reading is still only 7.4 Brix (1.029). Looks like this is going to be a very interesting experiment...

[BrewMasterBrad]

The boiling at 200F is very odd indeed.

I am wondering if the lactic acid may have strange refractive qualities that are throwing off your refractometer readings.

[bwarbiany]

I thought it might be the refractive index of the lactic acid until the corrected gravity reading perfectly matched the hydrometer reading.

It'll be interesting to see what comes out of this.

[bwarbiany]

Whatever this thing is, it's fermenting pretty actively...

[Justin H]

I know you mentioned using lactobacillus delbrueckii but it didn't saw where you got the culture.
This is actually a pretty common occurrence if you used White Labs (WLP 677) as your lacto pitch. I hear lots of people complaining about White Labs having a yeast infection in their culture, but it appears to be a mutated strain.
http://www.themadfermentationist.com/20 ... e.html?m=1
If you try this in the future, repeat the same process (but with a pasteurization step this time) and try a different lacto source (e.g. WL lacto brevis or a probiotic culture). You should have much better results.

[bwarbiany]

I know you mentioned using lactobacillus delbrueckii but it didn't saw where you got the culture.
This is actually a pretty common occurrence if you used White Labs (WLP 677) as your lacto pitch. I hear lots of people complaining about White Labs having a yeast infection in their culture, but it appears to be a mutated strain.
http://www.themadfermentationist.com/20 ... e.html?m=1
If you try this in the future, repeat the same process (but with a pasteurization step this time) and try a different lacto source (e.g. WL lacto brevis or a probiotic culture). You should have much better results.

Thanks... I think that was the strain I used, actually. That explains a lot.