Barrel Aged Beers: Subtleties and Soliloquy
I know it’s been awhile since my last entry, so I’m going to make it up to you by talking about a subject that might be of interest to many of you, and is very near and dear to my heart. Today I’m going to tell you a little bit about barrel aging beer: why we do it, what kinds of beers to do it with, and most importantly, the actual process of barrel aging and how it will impact the characteristics of a beer.
Aging beer (or any liquid, for that matter) in wooden barrels goes back to the days prior to the industrial revolution when making metal vessels larger than a cooking pot or a pan was an expensive proposition. Wooden barrels with metal bands around them provided an ideal solution to the storage of everything from flour to gunpowder, water to wine, and of course beer. Barrels were used extensively on sailing ships to provide what at the time was the height of waterproof food and beverage storage for long periods.
Okay so we know everything was stored in wooden vessels of some sort in “ye olden days”, including beer and wine, but why do we still do it? Wouldn’t it be simpler and more efficient if we just threw everything in a stainless steel tank, put chunks of wood in there and let it age that way? Simpler, yes, but far from more efficient, the reason lies in woods ability (when saturated with liquid of course) to expand and contract with variations in external temperature. When it heats up, the wood expands, when it cools off, the wood contracts. Through this expansion and contraction the liquid inside the barrel is forced into and out of the wooden staves, and extracts compounds from the wood (mostly wood sugars) in the process which add complexity to the beverage stored inside. This also causes a better known, but less appreciated, phenomenon within the barrel. Since the wood is porous, it isn’t perfectly sealed from the outside atmosphere, and while barrels are adept enough at keeping oxygen out, they are well known for evaporating water through the staves. Distillers call this the “angels share” because it was believed that the angels would drink the evaporated spirit. People often don’t realize and/or appreciate the effect this has on the liquid inside the barrel, since only liquid is being evaporated off (water, alcohol) all the flavor compounds dissolved in the beverage stay in the barrel, in effect getting concentrated. Couple this with the fact that, as a barrel evaporates its contents, it is continually being topped off with new product, and you have a beverage that will have a stronger flavor profile than the original product ever could.
But one does not simply barrel age any beer, for even though the process is slow, oxygen will eventually be introduced into the beer, no matter how often the barrel is replenished. It is for this reason that stronger, darker beers are more amenable to barrel aging than weaker, lighter beers. Light beers are often valued for the lightness of body and flavor, whilst many of the characteristics of darker/stronger brews meld nicely with flavors coming from a wooden barrel. Darker beers also tend to contain more anti-oxidant power to combat becoming stale and beer oxidation than lighter beers. That being said however, there are no other hard and fast rules for which beers to barrel age, results will often be a combination of time spent in the barrel, the amount of hops used (both dry and in the kettle), the alcoholic strength of the beer, the size of the barrel and, most importantly, a watchful eye by the brewers themselves.
As I have talked about already, liquids tend to pick up flavors from the wood via a series of expansions and contractions that pushes the liquid through the woods’ pores. While you can pick up ordinary oak flavor this way, many people aging spirits or wine/beer in barrels choose to toast or char the oak barrel on the inside before depositing their beverage of choice. This is because toasting or charring the wood will provide a greater surface area for the liquid to enter into, but also because the toasting/ charring caramelizes the wood sugars and unlocks many other flavor compounds such as vanillin’s, that contribute desirable characteristics into the beverage sitting in the barrel. Most often, brewers choose to age their beers in barrels that have already had spirits placed in them (with the inside of the barrel being charred already, of course) because many of the desired flavors are already dissolved in residual alcohol in the staves of the barrel. Many brewers will also want the characteristic of the spirit to be imparted, but at this point, as much of the flavors are being derived from the barrel as from the spirit itself. Again, we see flavors that meld well into darker beers such as vanilla, roasted nuts, oak, or toast. And that friends, is barrel aging beers 101, of course you can throw in whatever fruit and what not you want with your beer, or even sour it using a lactobacillus culture once the beer is in the barrel. The possibilities are endless, but, above all else, it must be carefully watched, as a goose would carefully watch a golden egg.