Options available to homebrewers include:
- Bourbon Barrel Chunks: You can find these in grilling supply stores, homebrew shops, and other retailers. These are large chunks of barrels used to age bourbon, sliced into chunks. Although often sold as a wood to be used for grilling meats and vegetables, it works just fine for brewing. These can be used to make a liquor tea or oak tea, which can be added at bottling time. These can also be added during the aging phase once fermentation has finished. I've even added them during the boil and left them in the beer during fermentation and aging.
- Oak Chips, Cubes, and Spirals: These are all basically pieces of oak in different shapes. They're available at grilling, homebrew, and wine making shops. Chips are smaller pieces that offer lots of surface area to impart flavor quickly to the beer. Cubes take a little longer to deliver oak flavor, but are easier to remove from beer than chips can be. Spirals are long rods of oak carved into a spiral shape that combines the flavor transfer speed of oak chips with even easier removal than cubes. These can be used to make a liquor tea or oak tea, which can be added at bottling time. These can also be added during the aging phase once fermentation has finished.
- Oak Essence: This is sold in beer and wine brewing shops. It's a liquid containing oak flavoring. It can be added during bottling, and allows you to adjust the level of oak flavoring to suit your taste or recipe requirements.
- Oak Powder: Similar to oak essence, this powder can be added at bottling time to add just the right level of oak flavor to your brew. It's available at some brewing and wine making shops.
- Liquor Tea: To make this, you begin by pouring the desired liquor (rum, bourbon, etc.) over the oak in a sealed container for a week or so. The liquor can be watered down if desired. The liquor will soak up flavors from the oak, and is added to the beer at bottling time in a manner similar to the oak essence or powder.
- Oak Tea: In this case, you put the oak in a pan with just enough water to cover it. This is boiled for 10 to 15 minutes, which sterilizes the water and extracts flavor from the oak. The water is then added at bottling time in a manner similar to the oak essence or powder.
- Oak Aging: Steam the oak for 15 minutes to sterilize it. Add it to the fermenter after the primary fermentation is finished and leave it in place during aging. Aging can take weeks or months depending on the level of oak flavoring desired.
Of course, the obvious "step up" from these options is to acquire an actual oak barrel and age your beer in that barrel.
Care and Feeding of Oak Aging Barrels
If you're thinking about adding an oak barrel to your brewing equipment collection, do some research first. Not only are they a significant investment in terms of cost, they have different cleaning and storage requirements than a carboy or fermenting bucket. Their special requirements also mean that eventually they'll acquire enough wild yeast and bacteria to begin having an impact on the beer. The methods discussed earlier don't have these disadvantages because the wood is generally discarded after each use.
The best way to maintain your barrel is to be constantly aging a new beer in it. This ensures that there is enough liquid in contact with the wood to keep it conditioned. If the wood gets too dry, the barrel begins to develop gaps that can cause leaks and contamination. Cleaning means filling it with warm water to wash out any trub and kill off any microbial contamination. Don't use chemicals, as these can soak into the wood and transfer into the beer. (Going in on a barrel with a few home brewing friends and passing it around is a good way to keep it in use!) Professional breweries use a steam injection system.
To store a barrel, flush it with warm water to clean it, as noted above. Fill the barrel with hot water and let it soak for at least an hour. Remove the water, insert the bung to seal it, then store the barrel in a cool, dry place. Ideally, you'll inject carbon dioxide into the barrel periodically to retard the growth of microbes. At some point, though, the microbes and wild yeast will pretty much make the barrel unusable.
If I could acquire a good bourbon or rum barrel inexpensively, I'd certainly pick one up and do a few barrel aged beers in it. However, given the fact that I'm not constantly brewing a new batch of beer, I think a barrel would be a bad investment for me. It would probably pick up too many wild yeast and bacteria before I would get enough use out of it to justify the cost.
I'll probably stick with the bourbon barrel chunks I bought at Jungle Jim's in Cincinnati and use those with oak teas, bourbon teas, or directly in the boil to impart the same flavors without the expense and nuisance of a barrel.
Naturally, you should do what's best for you.