At the Great British Beer Festival I was invited to the Tasting of Fullers Brewer's Reserve No2, and a damn fine beer it is too. I had already been drinking a few beers of the Bières Sans Frontières and am still not convinced I have fully appreciated this beer, nor do I remember the exact detail of the talk John Keeling gave. I have a couple of bottles here so I will try to rectify my lack of full appreciation on another occasion, just so long as I don't do what I did last night and weigh into a bottle after the pub, when my palate is half shot.
Whilst I can try the beer again, what I always fail to do when listening to great brewers talk is remember all the detail of the brewers knowledge. John talked about the technicalities of bottling barrel aged beers, not a subject I'm completely incompetent at, as the success of Æther Blæc has proved, but I'd be a fool if I even pretended to know as much about the microbiology of beer as John does.
I seem to remember John talking about the brewers reserve No2 being a little more susceptible to Brettanomyces generated flavours as brandy has a lower ABV than whisky at cask strength. Actually, I can find no evidence that cask strength brandy is any weaker than cask strength whisky, so I may have misinterpreted1 this point.
Whether specifically about the No2 or generally about barrel aged beers the point about the microorganisms in the wooden cask is important. John indicated that to enable the beer to be stable after bottling, chill filtering is required, and the beer reseeded with yeast. Although I don't chill filter I am very careful to get very good, recently emptied, long matured whisky casks for my whisky aged stout; this ensures as sterile an environment as possible before the beer comes into contact with the spirit soaked wood. Storing in as cool an environment as possible during maturation is also important.
I know of beer commentators who are horrified at the idea of bottle conditioned beers being re-seeded with yeast. Some purists think that the only correct way to make bottle conditioned beer is to chance the yeast from primary fermentation being strong enough to ensure secondary, anything else is cheating. This could not be a more erroneous point of view.
It is also worth referring back to a post by Zak Avery about beers that go wrong, the dicussions in there about Brettanomyces and a suggestion about pasteurising is interesting; every brewer has to consider what is best for their beer and moreover may not get it right every single time.
I would never make a bottle conditioned beer that wasn't first cleared in conditioning tanks, or perhaps a whisky cask, and then re-seeded and almost certainly primed at the bottling stage. I choose to use finnings where appropriate to clear the beer. Chill filtering may well have advantages to ensure unwanted spoilage microganisms are removed. I understand that Thornbridge have a shiny new centrifuge2 which should remove these pesky little guys but leave the flavours much more intact.
I suspect that any good bottle conditioned beer will undergo some form of treatment indicated above. I certainly re-seed every bottle conditioned beer I make, it's madness not to.
This makes me wonder about the "fizzy chemical beer" mantra that occurs in some circles. The use of modern techniques and equipment to ensure quality beer doesn't mean the beer is not a high quality worthy product. It does not mean that re-seeded bottles are inferior to the purity of a bottle that depends on the primary fermentation yeast, quite the reverse. It does not mean that a keg of unfiltered beer is somehow inferior to a poorly kept cask of some poorly executed clone of yesteryears mild, quite the reverse. It does not mean that a week old cask kept under a gentle blanket of carbon dioxide is inferior to a 3 day old cask of the same beer even under ideal cellar conditions, quite the reverse.
As we improve our brewery and our abilities we will be turning to technology to help us out at any point we feel it is appropriate, we hope it will make our beer better and better and better. If it loses us points with the purists then so be it.
1I sometimes wonder if my honesty is what keeps me from getting any paid writing roles; after all, a real journalist wouldn't be caught admitting that the story might not be true.
2Look in the comments in this post.