It seems fair to say that Chicago's Goose Island Beer Co., owners of the largest barrel-aged beer program in the United States, would like to have a do-over on last year's Bourbon County Brand Stout release.
Four out of the six BCBS variants released in 2015, including both the original and variations like the Coffee Stout and Barleywine, were subject to recalls and refunds. This was chiefly thanks to some unwanted lactic-acid bacteria getting into the kegs during the aging process, resulting in beer that (especially in Coffee's case) produced bizarre sour and chemical-like flavors that grew more pronounced as 2016 wore on. There are also reports that 2016 BCBS will be scarcer on the market than last year—especially in GI's more far-flung distribution areas like Oregon—because quite a number of barrels had to be dumped due to further lacto-infections.
Why did this happen? Poor luck coupled with practices that, in hindsight, may have led to contamination risks. For example, it's a somewhat common custom to back-flush bourbon barrels in order to extract the so-called "devil's take"—the bourbon that gets absorbed into the barrel wood. Going overboard with this, however, can leave barrels dried out, and dried-out barrels can lead to low pH levels and an inviting environment for unwanted foreign invaders.
Goose's solution with the four BCBS variants they're releasing in November was to subject them to "flash" pasteurization, which typically involves heating beer to 160 degrees for 15 to 30 seconds then rapidly cooling it down. In a blog post, GI brewmaster Jared Jankoski assured readers that this would have no negative effect on the beer: "The key benefit is microbiological stabilization, which is helpful for wood-aged beers where the barrels we use can be inconsistent. Most importantly, there is no discernible flavor impact."
Pasteurization and beer have a long history—Louis Pasteur invented it in the first place to keep beer and wine from souring; milk pasteurization wasn't standard until much later. Some beer fans have voiced concerns that killing the active yeast in future BCBS batches would rob the beer of whatever changes the aging process would bring out, a key factor considering how much fun taste-testing multiple BCBS years at once can be.
But then again, look at Deschutes. For barrel releases like The Abyss and Black Butte, they've been flash-pasteurizing the barrel-aged part of the blend since 2010, after a Brettanomyces infection struck several special releases in a row. Has that affected the quality? No—and whenever the brewpub offers Abyss verticals, every year still has its own individual flavor while retaining the properties that make the stout stand out so much. And while it remains to be seen whether GI can duplicate that success, GI implementing pasteurization certainly isn't going to stop the upcoming Black Friday assault on beer stores nationwide.