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Wednesday, October 03, 2007

Guinness, Brettanomyces, and Me

The St. James Gate Brewery in Dublin produces a beer called Guinness--you might have heard of it. Actually, it produces a whole bunch of beers, and they're all called Guinness. They vary from the light-bodied draft beer you get in pubs to a strong Nigerian version that employs sorghum rather than barley. My favorite--and one of the best beers in the world--is the strong version you can find in bottles with the name "extra stout." What makes it delightful are not the virtues of density and creaminess (though virtues they are), but a characteristic sour tang.

Jackson attributes this to funk resident in the crevices of the 100-year-old wooden tanks at St. James Gate in which only the strong stuff ages. Diageo, the parent conglomerate, denies this, but something's causing it. Rumor (and Jackson) credit a certain strain of yeast known as Brettanomyces. In the brewing world, Brett cultures have notorious reputation and are mainly regarded as contaminants. So profound is Brettanomyces (the cool kids call it "Brett") that brewers regard porous equipment (plastic, rubber, cork, wood) as permanently defiled and useable only in beers where Brett character is tolerated. On the other hand, Orval, the extraordinary lambics, Belgian browns and reds and others include it in their world-reknowned recipes. So you can't throw the Brett out with the bathwater.

I have decided to test the theory. I am in the midst of brewing up a batch of Irish stout, a fairly standard recipe that employs roasted barley, as appropriate to style. But after an initial fermentation with a standard ale yeast (I eschewed an Irish strain, rogue that I am), I'm going to dump in a Brett culture to finish it off. Brettanomyces are apparently voracious eaters and can gobble down sugars regular Saccharomyces (ale yeast) can't digest. Brettanomyces--the goats of the yeast world. My intention is to give the beer a wee taste of the sour without overwhelming it. We shall see.

In any case, I will report back as the experiment evolves. I don't know that I can prove what lives in the vats at St. James Gate, but you never know. I may also prove what doesn't live there. Stay tuned.

4 comments:

df said...

Are you suggesting that this yeast is only found in the extra stout version?

Also, I never realized that the beer in the draught version was different than the extra stout version other than the added nitrogen. That explains why it is so much lighter, I had always assumed it was just a function of the nitrogen.

Jeff Alworth said...

I am suggesting that, or rather depending on others who suggested it first.

Brettanomyces is a wild yeast, and wild yeast can "infect" equipment. Lambic brewers use this to their advantage and ferment in areas saturated with good wild yeasts. Brett is more pernicious, and usually when it gets into something, brewers want it out. But Jackson and others have suggested that the vats contribute this zing of flavor because they're infected.

And yes, only the higher-gravity beers are fermented in the big vats, so they are the only ones in contact with the Brett.

Jeff Alworth said...

Sorry, sloppy language. The beers are not fermented in the vats, they're aged there. I know you knew I knew the difference, and I appreciate the graciousness in overlooking this.

Brad said...

So Jeff, how did this turn out?

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