Wood and barrel aging provide depth of flavours, bringing out the complexities of some beers, while allowing others to smooth our and mellow creating deep and rich flavours. Spirit and wine barrels offer additional flavours of what was previously aging in them, imparting some of that character to what is aged in the barrel after. Recently other industries have started to barrel aging, opening the door to barrel aged coffee, cocktails and even maple syrup. This article will give your a quick rundown on wood and barrel aging, and hopefully get you to try some of the barrel aged beers that are coming out now.
Wood
Wood provides both a medium for fermentation and aging as well as adding a variety of complex flavours and aromas. Some of the chemical compounds in the wood will impart caramel, vanilla or coconut aromas and flavours. Additionally, bourbon barrels are commonly charred on the insides, ranging from a light toast to a heavy roast and char. This converts the hemicellulose (a polysaccharide that is more complex than a sugar but less than cellulose) into wood sugars, offering up flavours of caramel and brown sugar. Vanilla notes come from phenolic lignin, while coconut flavours come from lactones. Together we get deep and complex aromas and flavours that are used to compliment similar characteristics in the beer itself.
The most commonly used wood in barrel aging is oak, but a variety of different types of wood that can be used for aging beer. American oak provides more vanilla and coconut aroma and flavour than the more subtle French oak, while Hungarian oak imparts vanilla and coffee flavours. Recently I came across some Spanish Cedar, Sugar Maple and Cypress spirals to try with wood aging, and there are many more different woods out there than the classic oak varietals.
Additionally, there is quite a selection of wood alternatives that can be used to impart barrel or wood character to beer, or can be used in addition to barrel aging to improve the wood character of the second or third use of a barrel. With all these alternatives you must keep in mind that the increased contact between the wood and the beer allows the aging process to speed up by increasing the volume to surface area ratio. With some of these alternatives you have to be very careful not to over do it. Here are some of the types of products used in beer.
Chips – Very high surface area will impart considerable flavour in a very short time.
Cubes – Lower surface area allows for slower release of compounds, while their size allows for some toasting.
Staves – Even lower surface area, and easier to find different types of wood
Spirals – Higher surface than staves and come in a variety of toast levels.
Barrels
First use barrels, 
ones which have not yet been filled provide an intense oak character. This might be overpowering for most beers, so it is common to fill it first with hot water to remove some of the wood flavours. Following their first fill, these barrels will have a significantly reduced oak character, but instead provide similar characteristics from what it previously contained.
Bourbon barrels are commonly used in the brewing industry due to regulations requiring charred new oak barrels for bourbon. This makes bourbon barrels very inexpensive and easy to come across. Other spirits though are now popping up for beer aging. Sherry, port and cognac are increasingly common, and even gin and tequila barrels are being used to age beer now.
After the second fill, the barrel will lose much of its oak and spirit character. This can be mitigated by soaking a bottle of the spirit inside the barrel or by using some of the previously mention barrel alternatives. Following the second or third use, the barrel started to offer little or no barrel character and are considered ‘neutral. These barrels are often moved to a souring program, creating a medium for the various bacteria and yeasts to ferment the sour beer without potentially compromising the clean fermentors.
The surface area to beer ratio has a dramatic impact on the flavours pulled from the wood. Barrel size is therefore very important when taking into account what you are trying to create. Some common sizes for barrels include small, 1 litre barrels can be found around town at some of the craft cocktail shops, generally used for aging cocktails (I have quite the passion for a barrel aged Negroni, it is my weakness). Small 19 litre, homebrew sized barrels allow for quick aging, but for some styles or sours they might need to be transferred to a glass carboy to finish up before they take on too much oak or spirit character. Most common in the beer industry are the 225 litre barrels. These are commonly used for wine or spirits first and are reused by brewers. Further up on the scale of barrel aging are foeders (also known as foudres or foedres). These are oversized oak tuns. The increased size, and thus the surface area ratio allows for longer aging of the beer.
Here is just a bit of information on barrels and barrel aging. There is much more to barrels than this short article, from fruit additions to souring in barrels. Wood aging offers a huge range of options for the brewer and consumer. And with more local craft distilleries, the opportunity for collaborations is there. Recently Four Winds Brewing did a tequila barrel aged Berliner, while Gigantic brewed a gin barrel aged IPA that was amazing. So look for some of the barrel aged beers that are coming out now, or try brewing one of your own.
Kerry Dyson
Vice President
CAMRA BC – Vancouver Branch
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