Leah’s Beer School: Lesson 32

Oak Barrels & Aging Beer

Wood has played an instrumental role in the brewing industry for hundreds of years. For centuries, wooden barrels have been used to transport beer, as well as providing a vessel for serving and fermenting, and recently there has been a resurgence in barrel-aging beer. 

History of Wooden Barrels 

The Gauls, a Celtic tribe in continental Europe, are largely credited with the invention of wooden barrels near the beginning of the first millennium. The Celts’ shipbuilding and iron working skills played an important to the development of barrels, as they used iron bands to reinforce and bind the barrel’s staves together.

Later, the Romans capitalized on this invention as a means to store and distribute their goods. Barrels proved to be a superior storage container to amphorae vessels, as they were watertight, durable and easy to maneuver. By contrast, amphorae, often ceramic, were breakable and very heavy.  

It wasn’t long before wood replaced clay and terra cotta for storing and transporting of goods. Because barrels were expensive and labour-intensive to make, they were reused as many times as possible. The same barrels were often used to store many different products.  

Barrels & Beer 

Due to the wood’s porous nature, beer had to be consumed relatively quickly or needed to be preserved by heavy hop rates and/or high alcohol content. At some point, the connection was made that the wood from the barrel itself influenced the flavour of the beer. More importantly, different types of wood contributed their own distinctive flavours to the beer. 

Oak has long been favored for the construction of barrels, due to its watertight structure and pliability.  All oak species can impart their own flavors to beer but until recently this characteristic was rarely desired. The use of wood was, for the most part, enthusiastically abandoned with the advent of metal kegs, fermenters and storage tanks.

French Oak v American Oak

The two most common types of oak used in beer production are French and American. White oak is used almost exclusively is barrel product, as red oak is too porous for barrel aging. Oak aging contributes aromas, flavors and tannin to beer.

French oak tends to impart more subtle flavours to beer, as it is much tighter grained and less dense than the American oak. On the other hand, American oak is almost twice as dense as French oak, can be sawn instead of hand-split, which is far less labour intensive. For this reason, American oak barrels are considerably cheaper than their French counterparts.

In terms of flavour, American oak is sweeter and contains more vanillin (vanilla) compounds and is associate with flavours and aromas of coconut, sweet spices and dill. French oak is often associated with aromatic sweetness, full mouthfeel, dark chocolate, savoury spices and roasted coffee flavours. 

Other Considerations 

Oak adds depth and complexity by adding flavourful and aromatic compounds to beer.  The age of oak, toast level and size of the barrel all have an impact on beer. New oak will provide more flavour and aromas when it is first used, and its impact will lessen as it is reused over time. 

The flavours and unique characteristics of oak varietals become more defined through the toasting process. Oak can be toasted to varying degrees, where lightly toasted oak will produce more subdued flavours and dark toasted oak will provide more carbonized or caramelized aromas and flavours. Flavours are imparted to beer through surface contact with oak, and the smaller the oak barrel the greater the impact of oak aromas and flavors.

Barrel-aging beer is an expensive process and breweries will often buy barrels previously used for spirits or wine. While barrel-aged beer is more costly than most of your average craft beer, the final product is generally worth the higher price tag.

(Leah is a Toronto based freelance writer as well as Head Beer Weenie and a server at C’est What)