From the HBD Archive
From: sherwood@adobe.com
Subject: beer gone bad
Date: 1992-02-25 17:47:16 GMT

A friend of mine has had absolutely terrible luck lately with his beer
making. After fifty or so batches with only two (easily explained) problems,
he has had to dump 3 out of 4 of his last batches. The symptom is a horrible
smell which carries somewhat into the taste. The closest thing we can come
with is a sour smell fairly similar to milk which has clotted and gone bad.
Definitely not appetizing. The smell starts mild, but then gets stronger
as time goes on. It sounds like an infection to me, but he is careful about
sanitizing everything that touches his beer.

Stuff which may or may not be relevant:

All of the batches which have gone bad have been all-grain. His successes were
with extracts (with adjuncts). He has had several good all-grain batches,
though, with identical procedure and recipie. He has fermented both in a
SS keg (Bud) and in plastic buckets with identical results. He brews 15 gallons
at a time, and so uses 3 fermenters when he uses plastic. When there has
been a problem, all have gone bad (ie, never just one fermenter).

He has had this problem with a variety of yeasts (Wyeast Irish, Munton&Fison
ale, Wyeast British). Around this time he started using a homemade counterflow
chiller which drops the temp to around 68F. He sanitizes the chiller well,
letting a bleach solution soak in the coils for a while, then running boiling
water through it to clear the lines. He has also had a lot of problems (but
only very lately) with stuck fermentations. In fact, without exception the
sour beers have ALL had stuck fermentations (though we were able to rescue
one by repitching a Munton & Fison yeast. Obviously a stuck fermentation
could give a competing yeast and/or bacteria a chance to grow, but why,
suddenly, are all fermentations sticking? I had always heard that extract
brews were more likely to stick; experience has shown exactly the opposite.

We figured maybe the pitching temp was too cold so upped it to 90F (about where
we had been pitching when he used an immersion chiller) for this last batch.
We also 'fanned' the wort against the sides of the fermenters to try to ensure
oxygenation. This batch started like gangbusters but seems to have stuck at
1030. Based on past experience we expect around 1018-1020. No sour smell this
time, though. Fermentation temp has been fairly constant at 65F. (I ferment
at 58F with no problems).

There are no visible problems with the sour beers. Even after a month in the
fermenter the beer appears perfectly normal (if you hold your nose). No
visible growths, normal ring of trub around the surface.

So anybody have any ideas? Before this string of problems there was NEVER a
stuck fermentation. Never this sour, rotting odor.

Geoff Sherwood

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