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General Category => Yeast and Fermentation => Topic started by: tmaurer on April 07, 2010, 07:35:53 am

Title: Yeast troubles
Post by: tmaurer on April 07, 2010, 07:35:53 am
I brewed a witbier recipe out of Zainasheff's Brewing Classic Styles.  I'm fermenting in a standard 6.5 gallon bucket.  I put 5.5 gallons in, and I usually put a blow off tube on the bucket because they're just not big enough.  I pitched a 1 liter starter of Wyeast 3944.  As the recipe states, I started fermentation at 68°.  During the last 3rd of fermentation, I took the blow off tube off the bucket, and I put an air lock on.  I ramped up the temp slowly to 72°.  Fermentation appeared to have dramatically slowed.

It now appears that fermentation has kicked back off immensely since kraeusen is coming up through my airlock.  Is this normal for fermentation to pick back up like this when raising the temperature?  Or is this a sign of something wrong?
Title: Re: Yeast troubles
Post by: tygo on April 07, 2010, 08:11:08 am
I don't think you have a problem.  I think it's very likely it's just what you said.  You raised the temp and that kicked the fermentation back into higher gear.
Title: Re: Yeast troubles
Post by: tmaurer on April 07, 2010, 09:12:45 am
Let me ask you.  When you a recipe that calls for an increase of temperature during the end of fermentation, is that because the recipe wants a very dry finish?  Wouldn't that be the focus for a witbier?  Where you would want to showcase the yeast and spices?
Title: Re: Yeast troubles
Post by: tygo on April 07, 2010, 09:29:32 am
Well, as long as you're fermenting within the acceptable temperature range (62F-75F for this yeast) you should get the same final gravity at say 65F as you do at 72F presuming you pitched a sufficient amount of yeast.  It would just take longer.  So it's not to obtain a more attenuated (drier) beer.

The reason you're ramping up the temperature at the end is to generate some additional phenols that are produced more at the higher temp to contribute to the "Belgian" flavor.
Title: Re: Yeast troubles
Post by: tmaurer on April 07, 2010, 09:43:51 am
Thanks for the info.
Title: Re: Yeast troubles
Post by: a10t2 on April 07, 2010, 10:19:26 am
That strain is just plain weird. The krausen may never fall, IME.