Recently, Mr. Pie started his very first batch of home brewed beer. He chose a Brewcraft USA kit, a clone of Rogue Hazelnut Brown Ale (unfortunately, I don’t see it listed on their website.)
Everything started out awesome: It’s a well-crafted kit, and included everything we needed except yeast. Because the kit included both grain and malt extract, we started out by boiling about 3 gallons of water, and buffering the carboy with another 2 (which we boiled and cooled beforehand). We boiled the wort Saturday night, and pitched the yeast Sunday morning. By Monday, it was fermenting vigorously, and it had stopped blowing off waste by the following Saturday. The next Sunday (one week after pitching), we transferred it to a second carboy to finish fermenting. Monday afternoon we peeked at it, and discovered that it was growing small white colonies. OH NO!!!!!
Luckily, it had only been about 24 hours since we had racked it, and it still smelled fine, so I thought we probably had time to save it. We transferred it back to the brew pot (a 5 gallon stock pot), and pasteurized it. When the yeast initially gets added to the wort, it’s a sterile environment, more or less – the wort has been boiled, for an hour or longer, and then cooled in its clean container. During the first (blow off) stage of fermentation, the yeast is multiplying rapidly, creating lots of CO2 and pushing all the undesirable gunk (malt protein, yeast waste, etc) out of the beer. Once that’s done, the yeast enters an anaerobic stage and begins producing more alcohol than CO2 while digesting the remaining sugars. Somehow, we had introduced something else into the beer while we were transferring it. Uh oh.
So, we re-pasteurized it, to kill whatever it was that had contaminated it. Unfortunately, this also meant we killed all the yeast. It’s important to note that we did not boil the beer, which would have caused the yeast cells to burst, which is bad. We just heated them up until it was too warm for them to live anymore. 🙁 We held it above 190 degrees F for 10 minutes, then used an ice bath in the kitchen sink to bring the whole pot down to a cool enough temperature to go back into a clean and sanitized carboy. We put an airlock on it, and the next day went to visit Sound Homebrew to get new yeast. We added the new yeast on Monday, and crossed our fingers. And checked the surface frequently.
A week later, nothing had grown on the surface. There had been a little bubbling in the airlock, but not much. At the end of the week, the water had begun to draw up, as the fermentation in the carboy slowed and a vacuum started to form. Hurray! We tested the final gravity and found that it was near our target range; a taste test confirmed that it was palatable and not spoiled!
It has now been transferred into a Cornelius keg, along with some sugar to help it pressurize. Initially we expected to be drinking it around Christmas, but I think Thanksgiving may be a reasonable target now.
I’m really pleased with how well this worked. When I suggested it, I was certain that I had seen it elsewhere, though my searching has not turned it up. The gentleman at Sound Homebrew (whose name I forgot) did mention that he would probably add malt extract along with the yeast, and I will second that advice. Our final gravity is a little lower than was expected, and the alcohol content seems a little low. We’re still going to drink it and be pleased as punch, but if you’re in a similar situation, I would add a pound or so of malt extract to the beer when you pasteurize it, to ensure that the new yeast has enough nutrients.