insanely fast fermentation

Lizzy · Apr 7, 2008

I just pitched my wort onto a yeast bed from a batch before, and I got VERY active fermentation in about 15 minutes, and it continued at an insane rate for about 12 hours, and now it is done. I checked the gravity, and it is where I expected my final gravity to be.
Is this to be expected from repitching? Or is this a sign of infection? I tasted the sample I pulled out, and there was a hint of sour fruitiness to it.
Has anyone else experienced this? And is there anything I can do about it now?

enderwig · Apr 7, 2008

It's not unheard of when pitching on a yeast cake. I would leave it in the primary for 7 days minimum, 10-14 is better though. The flavors should mellow with a little aging.

Yuri_Rage · Apr 7, 2008

The fruitiness comes from esters produced during a hot ferment. Because it was so vigorous, the temperature probably rose almost 10 degrees (F) over the ambient temperature in the room. Some of that character may fade over time, but probably won't diminish completely.

david_42 · Apr 8, 2008

Very fast ferments are one of the reasons for pitching on the cake. But this also means a lot of heat gets generated raising the temperature, hence the fruitiness. For that reason, I'll cool my wort down to the bottom of the yeast's temperature range before pitching.

MR. Zak · Apr 8, 2008

I concur its not a bad thing pressure and temp are the two main things to concider but David is spot on lower the temp of the pitching wort and also you could put the fermentor some place colder and see how that plays with the internal temp but controlling the pressure and temp will help you get the fruitiness to stay lower at this point you could send Co2 through the bottem of the fermentor and "scrub" out the esters
Z

AndrwHock · Apr 9, 2008

Definitely leave the beer sit for 10ish days on that cake, then rack it. it'll give the yeast some time to clean up after themselves. If its a bit lower in temp, it could take care of the fruitiness for you like these guys said.