Tuesday, May 28, 2013

Yeast Killer

Anyone who brews will tell you that tucking a fresh batch away in a fermentation chamber is like tucking your kid into bed for the first time -- you want to go back and check on it at least once an hour to make sure everything's okay.

At least that's how I feel about it.

Typically, signs of fermentation will appear within 24 hours of pitching the yeast. Since I use plastic buckets (as opposed to clear glass carboys), the only sign I have that fermentation is happening is by watching the airlock bubble.

Since the KGB Stout has about twice the amount of sugar and yeast than a typical brew, I was really expecting this thing to take off on me. So much so that instead of a typical airlock (which can clog and literally cause the fermenter lid to blow off), I went with a blow-off tube instead.

One end of the tube pokes through the lid of the fermenter,
and the other end is submerged in a growler or similar container of StarSan.

Side Note: Here's what a nasty mess a blow-off is:

Yeah, I do NOT want that to happen to this batch.

Funny story -- that picture actually comes from No Meat Athlete which is a blogger Jennifer has been following for a long time now (for obvious reasons). I always forget that he's a homebrewer, too! It's crazy that HIS picture is the one that comes up when I Google searched "fermenter explosion."
Anyway, when things were STILL quiet on Monday morning, I knew something was wrong.

I had the fermentation chamber set around 18*C, which is 64*F. It will swing about a degree either way, so the beer should stay anywhere between 62*F and 66*F.

But when I felt the side of the bucket, it was really cold.

I decided to crack it open to see what was going on and to get a temp. There was a little bit of activity, but not much. And then I saw why.

Yep. The beer was 45*F!

Then I realized what the problem was. In order to make sure the beer stays between 62 and 66, I have to put the temperature sensor's probe in water instead of just inside the fermenter. That's the black wire you see going into the little can with the green lid in the back.

I guess when I was moving things around the probe slipped up and out of the water in that container, which made the ambient air temperature in the fermentation chamber 62-66*F, but the beer was much colder. (Which is still odd, especially since fermentation gives off heat. In fact, I made the fermentation chamber because my beers were fermenting too warm when I was keeping them in our coat closet where the ambient temperature was around 73*F.)

When I put the probe back down in the water, then my temperature controller showed a more accurate number...


What did this do to the beer??

Hopefully nothing. When yeast get cold, they just go to sleep. Of course I'm no yeast expert, and some of them have probably died, but I'm hoping that there's still enough of them in there to get things going again once the beer warms back up.

I made sure to let it warm back up gradually, and I gently rocked the fermenter back and forth a little to re-suspend them again (they fall to the bottom when they go dormant), so I'll give it another day or two before deciding if I need to pitch a new packet of healthy yeast. Chances are I won't have to do that.



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