October 25, 2011

Solera-style oaking?

Oak aging is all the rage in brewing. Everything gets oaked these days, even beers that normally need to be drank young. Harpoon last year released an oak-aged dunkelweizen; it was incredible but probable wasn't really "aged" because weizen beers lose a lot of their flavor quickly and this one had all the great flavors and aromas of a dunkelweizen but with delicious oak notes.

I think of oak as being used in two ways. One is oak aging: where beer is stored in oak barrel (or devices designed to mimic cask aging) to produce both the oak flavors and an aged flavor in the beer, such as sherry notes from slight oxidation, some acetic character, smoothing out of alcohol notes, etc. This sort of aging can run from months to years and depending upon the newness and quality of the barrel will produce different effects. On the other hand, oak (by chips, cubes, strips, dowels and so forth) can be added to the beer to produce only oak flavors and will produce those notes in a matter of a few days (if the oak is very new) to weeks or months (if the oak is a bit aged).

The two products produce different results in beer as a result of different processes involved. Neither is better than the other but you can't do one and get the effect of the other. A Flanders red might be oak aged in a way that creates both oak flavors and acetic character from access to small amounts of oxygen. That oak aged dunkelweizen had to have oak added to the beer to create oak flavors without losing the fresh wheat beer flavors (although I might be wrong -- large scale breweries can do different things than we can at the homebrew level; certainly as homebrewers to recreate this you would not barrel age).

One of the problems with using oak chips or cubes (especially chips) is that the first few times you use them you get a lot of woody flavor and it is very strong. Over time they mellow and create more barrel-like flavors. You can steam them or boil them to sanitize but also to draw out some of the harsher, young wood flavors. I've boiled chips for hours and still had a lot of wood taste overpowering the vanilla-like flavors normally perceived in oaked beers. This is a problem I set out to overcome.

Sometimes chips and cubes are soaked in various alcoholic beverages, from vodka to whisky to scotch to wine, in an effort to both sanitize the wood and bring some of the flavor from the alcohol into the beer. This is very common with sours, trying to mimic the effect of barrel aging in wine barrels, to beers aged in bourbon barrels. This works well for its intended effect but typically doesn't help with the woody flavors, since people tend to let the oak sit for a week or two. As a side note, one thing I have had good success with is soaking oak chips in liquor or wine and then adding it back to the main bottle it came from to create complexity in the parent beverage. A cheap, jug chardonnay will improve dramatically with some oaking, as will a cheap scotch or whisky. It won't make it a $100 bottle but it will add a few dollars. It's a good way to let the alcohol pull out some of the oak flavor and woody flavor and pass it on to a liquid that might sit for a while and help the woody notes dissipate so it is less noticeable.

Another risk of adding chips and cubes, especially chips, is that it is so easy to over oak a beer. If you over oak, especially with young oak that has a lot of woody notes, you can be forced to wait months for the oak and wood notes to mellow. Even then you may not get rid of the woody character. This is typically less of a problem with sours that get aged for months or years on the oak but it could be a real problem for that oaked IPA you're trying to make.

So my goal was to create a way to:
  • add oak to beer without getting the woody character
  • add oak to beer with a more mellow, aged flavor
  • control the amount of oak addition
  • be awesome.
Given my interest in solera-style brewing (see the lambic solera process) I thought about how that might be used to accomplish my goal. I've created an oaking solera. I took some oak chips and boiled them for about an hour, draining the water and adding fresh water, to get rid of some of the woody character. I then added vodka to both sanitize and draw out the flavor and color of the oak. I will let the vodka sit, causing a mellowing of the flavor, and add just the vodka to brews as necessary to create the oak flavor. I can let the oak sit essentially forever, pulling off what I need and adding fresh vodka as I use it. If the oak flavor gets too mild, I just add a little more oak. By letting it age in storage over time I get the effect of long term aging without tying up a beer to get it done. It won't quite give the same flavor as oak aging but closer than adding fresh oak. (I could always add a hint of sherry to get that slightly oxidized flavor.)

The benefit of separating the oak and having it always available is two-fold. First, I have less of a risk of over-oaking because I can add, taste and repeat until it reaches the desired point. Second, I can add oak in the bottling bucket, or even individual bottles, to create a batch of beer that is partially oaked and partially un-oaked for greater variety.

One concern is whether adding vodka will just result in boozy beers. My hope and expectation is that the oak will be concentrated enough that it will only take a few drops per bottle to create sufficient flavor. If not then I might have to rethink the applicability of this approach. Possibly giving the vodka a quick boil to drive off the alcohol will produce the flavor without the booze. That's something I'll have to test when the time comes.

Of course, these are my expected results. I just started this and have not yet tried the end result, although I intend on making an addition to a mead I have aging very soon. I want to give the oak a little time to lose the woody character. So I guess once I have some opportunities to experiment with this I'll report back the results.

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