News & Reference

Fermentation Alert!

Homebrewing

The All Grain Brewer   |   Thursday, February 16 2012

Lessons learned :  The importance of temperature, roused yeast cakes, blow off tubes, and an understanding spouse.

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Fermentation Alert! This winter I have been having all kinds of hardships with fermentation whether it is over fermentation (I’ll explain in a second) or under fermentation.

Under fermentation is really the main issue that I have been battling. This is primarily due to the fact that the temperatures are just cooler in my house during the winter. My basement is between 61 and 62 F. My living space in the house is around 67 F.

Here is one scenario that happened to me earlier this winter. I had brewed an American Stout, and was going to use the yeast cake for a Russian Imperial Stout. Now this yeast had the beer pulled off of it for about two weeks. During that time the yeast cake had been sitting in the carboy in the basement with a CO2 cap on it, of course. So after brewing the Russian Imperial Stout, I poured that wort on the American Stout yeast cake.

I then expected fermentation to be started within about 3 or 4 hours. The next morning I walked downstairs into the basement, and nothing was happening. Hmmmm, at that point in time I had to get to work, so I hoped when I got home that it would be bubbling.

Later in the day, I called my wife from work to see if there was any fermentation activity. She reported none. Now I started thinking that maybe that yeast cake had died on me since it sat without beer on it for two weeks or so. On the way home, I stopped by the local homebrew store and picked up a vial of yeast to try and save the Russian Imperial Stout.

When I got home I went into the basement to check on the beer. I noticed my thermometer in the basement was dead, so I put in some batteries. It was 62 F! Hmmmmm, could it be that the wort / beer was just too cold. So instead of pitching more yeast in the Russian wort, I took the carboy upstairs and put it over the heating grate. I then wrapped a heating blanket around it. I put the heating blanket on low for 20 minutes every hour for about 3 hours. By the time I went to bed the wort had started fermentation.

Here are my lessons learned.
1) I should have started fermentation at a warmer temperature – that’s now obvious
2) I should have roused the yeast cake. What does this mean? It means that I should have shaken the stuffing out of the carboy when only the yeast cake was in it right before I pitched the initial wort. That way the yeast cake would not have been a cake at all, but instead it would have been a slurry that would have been ready to easily blend into the entire volume of wort. Lessons learned.

As for over fermentation, I had a problem this weekend. I brewed a Belgium Dark Strong, pitched onto a yeast cake slurry, and sat it upstairs in 66 to 67 F temperature. It was bubbling the air lock within three hours. When I woke up the in the morning the cap on the airlock had blown off. The fermentation was so vigorous that the yeast went into the air lock and then plugged the small holes in the cap of the three piece airlock. This allowed pressure to build up in the carboy and then the cap blew-off. Two handfuls of yeast where on the outside of the carboy, and the carpet was a bloody mess.

The worst part happened when I looked up. The ceiling was peppered with yeast from where the cap hit it, which was about eight feet away. I have now been scrapping this off the ceiling, and have about three hours into the clean-up. I think I have about three hours left before I am complete. The carpet itself took me about an hour to clean-up. Amazingly I am still married.

I should have had a blow off tube for this beer during initial fermentation. A blow off tube uses a hose that goes into a bucket of water for the “air lock”, and it allows much more volume of C02 and any bubbly yeast to blow into the bucket.

The All Grain Brewer Has Spoken