When I posted about my stay in Denver over Christmas, I talked about going to Flying Dog Brewery. While there I was able to pick up three great unique beers, first there was the Oak Aged Horn Dog, then Collaborator, and lastly this beer. Its an Oak Aged (for 6 months) Imperial Porter that has been "infected" with Brett. Brett is short for Brettanomyces, and is a acidogenic yeast compound and when grown on glucose the yeast produces a large amount of acetic acid. In the wine world, winemakers will go to great lengths to keep Brett out of their wine beyond very very low levels. At these low levels Brett can create positive sensory complexity, however beyond that the wines can be described as mousy which doesn't really sound like a good thing. However beer behaves differently when Brett is introduced. Certain styles of beer, specifically Belgian styles such as Lambic and gueuze owe much of their complexity to Brett. In Orval for example, the brewers add Brett to the bottles helping to give it its unique taste. With all of these examples you can see that the addition of Brett gives a degree of 'sourness' to the beer.
The Beer: The beer pours a very dark brown with a thick cappuccino colored head. The nose has raisins, chocolate, cherries, vanilla and some oakyness. The taste has an underlying sourness, along with cocoa, raisins, toffee, roasted malts, bitter espresso, and a hint of molasses. The beer is smooth, its an interesting brew, and its not a session beer. I think there's too much going on here, to drink more than one. The sourness is not that overpowering, but the bitterness is. Its a weird combination of sour bitterness, going on but the bitter compounds far outweigh the sour ones. A little alcohol-y too. This isn't to say I didn't enjoy the beer, I did, and I also respect what the folks at Flying Dog were attempting here. I think its incredibly interesting beer, but definitely not my favorite. I'd give it a C+.