Barrel Aged Beer Making A Comeback
At one point in the history of beer making, all ales and lagers were aged in barrel, as well as conditioned or at least served in barrels, foudres or puncheons. Over the last couple of year, this tradition has come back into fashion and pushed aside the more common practice of ageing in stainless steel or other modern vessels. Wood not only imparts a preservative quality to the notoriously delicate product but also flavour characteristics depending on the barrel's previous occupant.
Everything from Bourbon barrels to Tequila, Scotch, and rum barrels are used, even wine barrels are popular with breweries. These wooden vessels provide brewers a playground to impart different flavour aspects into the beer, making them the boozy equivalent to desserts. These so-called pastry stouts emulate s'mores, doughnuts, cakes and pies.
Source via: Wine Enthusiast