What effect does storage temperature have on the aging of bottle conditioned homebrew? At the beginning of August in 2013 I put a bottle of oatmeal stout, brewed in June, into the fridge, and another into the coat closet. One year later, I chilled the closet bottle for a day, and opened both for comparison.

First stage: the triangle test. Both my special guest taster and I were able to correctly identify the odd one out. You might guess, based on the picture below, that the sample on the left is the correct choice, but in fact, it’s the sample on the right. There was a slight difference in appearance, but it isn’t captured well in the photo below (the difference was more clear when a full glass was poured). The difference in taste was much more apparent.

The beer that aged in the closet was clearly sweeter and boozier, with lower carbonation and head retention. It had notable prune and sweet dried fruit flavours, while the fridge aged beer retained roasty coffee flavours that were almost absent in the closet beer. This is conventional wisdom confirmed, as you’ll frequently see ‘sherry-like’ in descriptions of the effects of oxidation on dark beers. Moreover, this change is attributed to the oxidation of melanoidins, which also fits with the disappearance of the roast grain flavours.

So, one year is enough time for a room temperature aged dark beer to lose much of its original character, which could have been retained quite well had it been in the fridge. I’d like to do a similar comparison after only a few months of aging, and check if the effect is already noticable. It would be very interesting to taste the fridge aged beer alongside itself prior to aging, but that’s an experiment which is essentially impossible for a homebrewer, as the same recipe will never produce exactly the same beer.