merkinman

Recipes 

I just tasted a hydrometer sample from a batch of Munich Dunkel which happens to be in the same fermenter that held a sour beer made by souring and then denaturing (30 minute boil) a portion of the wort.

My dunkel is now very sour with a very sharp flavor. My first guess is that the boil did not denature the lacto, but then again, the carboy was thoroughly soaked and scrubbed, and then sanitized with star- San. Another guess is the washed yeast I used for this batch, but I am skeptical of that too since I did not smell any kind of lacto character in the rest of the yeast as I was dumping it.

I do not think it could have been infected by airborne bacteria. The carboy was covered with foil (sprayed with star-San) for the first few days, and then plugged with a blow-off tube (end submerged in jar of star-San).


Ideas?

Stratotankard

Recipes 

I'm a bit confused. Did you sour mash and then boil all your wort for 30min before going to the fermenter? or did you only boil part of the wort before fermenting? If the first, you should have killed the lacto in the boil. If the latter, you would still have live lacto in the fermenter and they would still (possibly) be there for your Dunkel.

I keep a separate set of gear for my sours just for this reason. Bugs can be tough to get rid of once they get a hold. or you got an airborne infection.

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merkinman

Recipes 

I soured half the wort after the mash with a lacto starter, and then denatured that half. I do keep separate equipment with the exception of glass carboys which I clean and sanitize very well.

ReverseApacheMaster

Recipes 

Is it possible you used some equipment prior to the boil on the sour batch with the dunkel? It is possible that some lacto survived on the carboy...

I do agree, the boil should have taken out the lacto. Lacto should be killed off at pasteurization temperatures.

merkinman

Recipes 

Update:

I just tried a sample from the intentionally sour beer, nd the sour nature seems to be rounding out as the Brett takes care of the sugars. If I had been unsuccessful in denaturing the lacto, the sourness would have increased. I am beginning to suspect the infection came from the blow-off hose, especially considering how hard they are to clean.

Luckily, the only "soft" pieces of equipment that have touched this have been the blow-off tube that I think caused all this and my "thief". I have been soaking the thief in star-san, and will likely give it the bleach treatment now that you mention it.