Maturing beer in wooden casks is a popular means of enhancing distinction to today’s breweries. Wood, though, is a complex material easily prone to host different microorganisms because of its porous nature. Imagine a very rigid sponge with walls soaked in bitter tannins.
To processing methods a recent study from the Brooklyn brewery in New York has compared a strong 1078 dark ale matured in wooden barrels at cellar temperatures of 9.5oC with the same beer matured in wooden casks at an ambient temperature – on average 14.6oC but ranging up to 24oC.
The results of subsequent tastings indicated that the cellar matured cask beer was more stable with fewer oxidised compounds. Unexpectedly though, the beer matured at ambient temperature was preferred in the taste test despite the presence of more off flavours. Cask maturation is clearly a complex process with an array of flavours seeping from the wood and associating with beer compounds. The study indicates that more conditions should be studied over longer periods but for now the best taste may be from the cask on the bar rather than that in the cellar.
For further details see. Browning, 2014. The Effects of Temperature on Major Beer Compounds During Barrel Maturation. Master Brewers Association of the Americas Technical Quarterly. 51:12-18.
Written by Dr Keith Thomas
Brewlab Director