Oak in Your Beer - Oak Chips and Barrel Aging
The use of oak and other woods in flavouring beer has enjoyed a resurgence recently among home brewers and some microbreweries. Oak is commonly used in winemaking and was once widely used to barrel beer. This week we look at using oak to flavour your beer.
When to Use Oak
Oak flavour does not match every single beer. Oak barrels were widely used for storing beer for thousands of years, however you probably don't want to accent your delicately balanced Koelsch or Bohemian Pilsner with oak chips. Oak is most strongly associated with English and some Scotch ales such as Old Ales, Stouts, Porters, Browns, IPAs and some Bitters. Some brewers have used oak in Belgian styles such as the darker Belgian Ales, Farmhouse Ale, or Saison. More rarely you will see oak used with darker central European beers such as Bock or Schwarzbier.
In general oak flavouring is associated with darker, older beers or beers replicating historic brewing techniques.
Types of Oak
There are many types of oak though the three most popular are American, Hungarian and French. French oak provides the mildest flavour including some sweet vanilla hints, while American oak gives the strongest oak flavour. Hungarian oak provides a middle ground.
The flavour of oak also can be changed by toasting your oak. The dark toasted oak has a more carbonized or caramelized flavour while lightly toasted or untoasted oak has a much milder flavour. Toasting is usually graded on a light-medium-heavy scale and you can purchase wood chips toasted at these different levels.
Forms of Oak for Homebrewing
• Oak Chips - These are the most popular form used in home brewing - typically the chips are sold in a bag and look like wood shavings. The small chips have a large surface area which delivers the oak flavour to the beer quickly. The only disadvantage is that the small chips can be hard to separate from the finished beer, so it is important to have them in a grain or hop bag so they can be easily removed after aging.
• Oak Cubes - Packages of cubes are also widely available from home brewing supply shops. They work similarly to chips but take longer to impart their flavour as they have much less surface area than oak chips. However, the advantage of cubes is that they can easily be separated from the beer when you are finished aging.
• Spirals - Though less common that cubes or chips, spiral cut oak is a compromise that offers a large surface area like chips but are still easy to remove like cubes. Therefore, they still impart flavour to the beer quickly but allow for removal. Their only disadvantage is that they are more expensive than chips or cubes.
• Oak Essence and Oak Powder - Oak essence (such as Sinatin 17) is a liquid flavour extract that can be stirred in at bottling time to taste. Oak powder is similar - essentially it is a powdered oak flavour stirred into the beer. Both works instantly and can be added in small amounts to taste.
• Barrels - Oak barrels offer both unique opportunities and challenges. They are generally pretty expensive to purchase unless you get a great deal on a used one, but they offer a lot of potential for reuse. They can be a challenge however, as older barrels can get infected, can leak, allow some oxygen in, and may have their own flavours depending on what they were previously used for. Some home brewers prize used sherry, whiskey and bourbon barrels for the added flavour they impart, but you need to make sure the flavour you want matches the barrel's previous use. Be very careful with wine barrels as most wine flavours don't go well with beer (try mixing them in a glass sometime). Wine barrels should be sanitized before use, and any barrel needs careful maintenance. Finally, it can take some time (often months) to achieve the desired flavour, particularly for larger barrels.
Oak Flavouring Methods
Three major methods are available to home brewers:
• Oak Aging - The simplest method - which involves adding the oak chips/spirals/cubes after fermentation while aging the beer. Also, this is the method used with barrels, since you store the beer in the oak barrel. I recommend sanitizing the chips/spirals/cubes first by steaming them for 15 minutes to reduce the risk of infection (don't use sanitizing solution as it is absorbed by the chips). Most home brewers add their oak shortly after fermentation completes and before bottling (i.e. in the secondary) and leave the oak in there until they achieve the desired taste - sampling every day or two. Some brewers with keg systems also add the oak chips/cubes in the keg itself - containing it in a bag so it will not block the keg's dip tube. Oak aging can take anywhere from a few days to several months depending on the oak used and desired flavour level.
• Oak Tea - You can boil the oak to make an oak tea. Simply drop your chips/spirals/cubes in enough water to cover them fully and bring it to a boil for 10-15 minutes. Once the tea is complete you can add it a bit at a time to the finished beer until you achieve the overall beer flavour you desire. Making a tea is much faster than aging with oak, and lets you more closely control the flavour.
• Liquor Tea - If you are looking to add bourbon, whiskey or your favourite liquor flavour to the beer you can make a tea using liquor instead. In this case you add the chips/cubes/spirals to a small amount of your favourite liquor (possibly diluted a bit with water) and let it sit for a week. Then mix the liquor in with your beer in small amounts until you achieve the desired overall flavour. Obviously, moderation is important here as the liquor can easily overpower the flavour of the beer or wood chips.
Beechwood in Beer
Even though one very large American brewer advertises their beer as "Beechwood Aged", beechwood chips do not actually impart flavour to the beer like Oak does. Beechwood is used because it has very low phenolic resins, so it won't flavour the beer. Adding beechwood chips to a beer provides a large surface area for yeast cells to attach to and helps in settling and clearing the beer. Beechwood is therefore added at the end of fermentation to help the yeast fall out more quickly which reduces aging time needed for commercial brewers.