Yes, that's right... wooden fermenters. Oak, actually, and if you want to get specific, it is Lithuanian (a.k.a. Memel or Russian) Oak. These tuns take at least two brew lengths to fill. At the time of my visit, the brewers were sanitizing one of them in preparation for a batch. They use peracetic acid, which clearly won't sanitize the pores of the wood, so a significant amount of the character of the beer comes from microbes living in the wood. I asked the brewers about the yeast they use and they said that they get it from larger breweries... and not always the same one! Again, given that I have not noticed significant variation in Traquair House Ale over many years, it further reinforces the suggestion that wild yeast play a big role in the flavour of the beers made here. This character is unlikely to get out-of-hand because the bottled beers are pasteurized (the beer is bottled in Tadcaster at Samuel Smith's Old Brewery, incidentally) and the cask-conditioned ones are consumed within a few months of production.
