From the HBD Archive
From: Mark Gryska <GRYSKA@cs.umass.EDU>
Subject: Cold fermentation and funny flavor
Date: 1989-09-26 17:20:00 GMT

Greg Crawford writes:

>Also, could anyone tell me what effect fermenting at too cold a temp.
>would have. The yeast is a liquid german lager and the fermenting
>temp. is 40 degrees. (This was before I bought my hunter energy
>monitor). The beer fermented to completion but there is a strange
>background flavor I can't put my finger on. Infection has crossed my
>mind but I have tried two beers like this with the same results while
>my ales fermented at 70 degrees have had no problem.

Your problem may be a high diacetyl level. There was an article in
one of the volumes of "Best of Beer and Brewing" (Vol 6 ???) about
production schedules for Bavarian beers. This confirmed the advice
given by my beer ingredient pusher regarding yeast strain #308. It
is advisable to raise the temperature of the beer just before it
finishes fermenting to 50-60 degrees for a diacetyl rest. The idea
is to let the yeast correct it's own mistakes, in practice a brewery
will add fresh fermenting beer to the lagered beer (krausening) just
before bottling. This brief fermentation will add CO2 and reduce
remaining diacetyl to acceptable levels. I'm shooting from the hip
here since I don't have my reference material at hand. I can post
specifics if anyone is interested.

- mg

Mark Gryska
gryska@cs.umass.edu
mark@zippy.cs.umass.edu


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