Wednesday, May 26, 2010

Exploding Beer, Part II

The following was written a couple of years ago, but never finished and so never published.

I had my second exploding beer experience this evening and for the second time I have coated the exposed floor joists above a furnace room with yeast-laden beer. This evening's experience, thankfully, wasn't near the mess or volume (in both senses of the word) as last time.

A few years ago I decided to brew a nice strong beer well in advance of Christmas, a "fallen angel trippel" (trippel=knock you on your ass) from Paddockwood Brewing. This "christmas beer" was flavoured with lots of tasty chunks of orange peel and numerous spices. Since a trippel is a big strong beer finishing out at over 10% alcohol, a helluva pile of strong healthy yeast is required so that they are so busy they can rip through all that candy sugar-supplemented malt and race to the finish before they even notice that they fermented themselves into a toxic concoction of their own waste byproducts (ironically, ethanol, that lovely waste product of fermentation, is toxic to yeast). In order to get so many yeast just rarin' to go, I started with a sort of mini batch of beer (ie a starter). Once that was growing nicely, I then tossed those billions of happily churning and very active fungi into the larger 5 gallon batch of my christmas beer, slapped the airlock on and forgot about it for a few hours. At some point in the day I checked on the beer and was amazed to see how quickly this batch of beer took off (I know that was my goal, but it was truly amazing to see) with a nice bit of foam (krausen) accumulating on the surface, the beer churning violently within from the yeast activity, and the airlock nicely bubbling away. Happy that things were proceeding so well, I returned upstairs for lunch. I think I was enjoying a nice rye bread sandwich when I heard it. A giant "WOOP!" from the basement, followed by a steady "fwoosh". I flew down the stairs in time to see the last of about 3 gallons of beer foaming out the top of the carboy in a yeasty orange and spice flavoured geyser, with a judicious portion of the beer dripping from pretty much everything in the room. It seems that the krausen had risen to the airlock and began coming out of the airlock. The airlock had then become plugged with the chunks of orange peel that were in the wort, trapping the CO2 that was being produced by the rapidly fermenting yeast (CO2 and alcohol are the waste products of fermentation, the process by which yeast consumes sugars for energy in the absence of O2). Not only did that begin to build up pressure behind the airlock, but it also caused a good deal of the CO2 to go into solution (just as it does when carbonating the beer after bottling). That pressure just continued to build up in the carboy until it released with a dramatic explosion, perhaps a couple of hours after first becoming plugged. The pressure in the airspace of the carboy caused the initial loud noise I heard and shot the airlock and carboy to the ceiling, with a good measure of the krausen to boot. Immediately after the explosion and the release of the pressure, an awful lot of CO2 came suddenly out of solution. This then caused the subsequent geyser of wort shooting out of the carboy and the loss of gallons of precious Belgian beer. Not to mention more mess.

Other than losing about half of my batch of beer, and making a sticky mess of my basement storage room, the beer itself suffered no ill effects. It finished out at a respectably high alcohol content of over 10%, and tasted great after it had over a year to age. As I recall, it was a little rough the first Christmas, but mellowed a lot with lots of time and was excellent by it's second Christmas. Such a big beer with a high alcohol content is not something you want to drink "green", but rather is to be put away to the back of the storage room and forgotten about for a very long time.

This evening's explosion was similar, but smaller in every way. I did not notice the noise, just the mess. The airlock and bung had gone missing, having ricocheted off into some dark corner of the furnace room. The beer was "smaller" (lower sugar content in the wort and thus lower alcohol in the end product), and the pressures involved must have been lower as not nearly so much beer was lost. However, there still was a mess on the floor joists in the ceiling above.

So, having learned my lesson twice now, I really should start using a nice big blowoff tube in my carboys!