Homebrewing Oak Alternatives

Back in the 1980s and 1990s brewers would often ask whether beers that spent a long time in oak casks, such as IPAs, would have an oak flavor. I would reply (accurately) that they did not, largely because the casks were treated before use, and were used over and over again. Indeed, they were often lined with pitch or even paraffin wax to make certain that no flavors would be extracted from the wood.

But American craft brewers and homebrewers are unquestionably innovative and looking to push the envelope, aren’t they? Right now many craft brewers have at least one beer maturing in an unlined wooden cask. In fact, sitting somewhere in the cellars of Wynkoop Brewing in Denver is an ex-bourbon cask containing a version of my Chancellor Ale (BYO, May/June 2006). A lot of craft brewers like aging in used bourbon barrels, which is a step on from introducing straightforward oak flavors, but the latter is also widely popular, and I’ll look at that first.

Adding Oak Flavors
The obvious way to add oak flavor to a beer is to age the beer in an oak barrel, but that really is not all that practical for a homebrewer. Small oak casks (5-10 gallons/19-38 L) are available but difficult to use in practice. The first problem is surface area; a 5-gallon (19-L) cask has about twice the surface area per unit volume of that of a typical commercial wine cask. This means that it is easy to overdo the “oaking” and to overwhelm all other flavor components. Also, because of the surface area effect, evaporative loss of beer through the porous staves of the cask can be significant during long aging, and will also result in loss of carbonation. And finally, the first use of a wooden cask will take out pretty much all of the extractable oak flavors, so it cannot be used again for the same purpose.

The more common approach, which avoids most of these problems, and whose effects are easier to control, is to add oak in some form or another directly to the beer. These “additives” were discussed by James Alexander in BYO’s January-February 2008 issue, so I won’t go over them in detail here, I’ll just summarize them in the table below. These are all much cheaper ($3-10 depending upon type) than a full-blown barrel, which can cost more than $200. I have not listed the different flavors to be expected from these since it will clearly vary according to the time of immersion (all these are usually added in the secondary fermenter). But the materials themselves, especially the cubes, come in a wide variety depending upon the source (commonly American, French and Hungarian oaks) and on the degree of toasting (light, medium and heavy). I have also seen cubes with whisky and Sherry flavors.It seems homebrewers favor cubes; I know that at least one major craft brewer has used them and I have used them successfully myself. As to what type of oak and degree of toast you should try that is a purely personal choice, decided by your own taste. I suggest starting with American oak at the lighter end of the toasting range. When it comes to addition rate and residence time in the beer start at the lower end of the range – you can always work up from there with later brews. As always make detailed tasting note on your early efforts in order to guide you on the next beer. Above all, do not assume that more is always better, and remember that the degree of oaking required will depend upon the style of the beer you are brewing. Adding oak flavor is definitely not a procedure where “one size fits all.”

Which Beer Should You Oak?
As with most changes in your approach to adding extra flavor to a beer you should always think carefully about what it is you want to achieve; do not just charge ahead or you may finish up with something undrinkable. Mainly you need to think about the normal flavor of the style you are planning to brew and whether oak flavor would just throw it out of balance, or would it add some welcome complexity. The main flavors we are concerned with come from vanillin (that is, vanilla like) and tannins (which impart astringency), though there are many other less well-defined contributors to oak-derived flavor, such as pepper and roasted notes. If you bear vanilla and astringency in mind it will be clearer as to which of your beers will benefit from oaking. There are no hard and fast rules, and much will depend upon your own taste threshold and like or dislike for these main flavors.

Low alcohol beers (below 4.5% ABV), such as milds, English brown ales, ordinary bitters and cream ales generally suffer from this procedure. They are likely to be dominated by oak flavors and prone to being spoilt completely by too much tannin. Much the same is true for light-flavored lagers, such as American Pilsner and Kölsch, as well as for the various forms of wheat beer (which are meant to showcase other flavors, particularly those derived from the yeast used). Any beer where full-bodied, well-balanced maltiness are the normal characteristics, such as bock beers, Scotch ales and wee heavies will not really benefit from excessive amounts of vanilla and astringency.

Hoppy pale beers are another story, however. Even a relatively low-alcohol beer like pale ale can benefit from a little oaking. Go very gently here though, and opt for light-toasted American oak cubes at a low rate, say 1 oz. (28 g), and let it sit only for two to three weeks on the cubes. More highly-hopped brews such as IPA, double and imperial IPAs, not to mention the ludicrously titled black IPAs, can be oaked to advantage. The high levels of bitterness and hop character will tend to hide astringency from the tannins, and the vanilla and roasted notes from the oak will help to smooth out the hop bitterness.

Oak is definitely not welcome in fruit beers for me as it will easily overwhelm the desired fruit character. I know a number of craft brewers have barrel-aged fruit beers, but that is usually done when they are looking for more funky flavors from Brettanomyces yeasts, which ferment very slowly. And you might be thinking at this point that I am going to say only big, high alcohol beers will benefit from oak contact. But I don’t think that is true for Belgian golden and tripel beers, since these are generally designed to be dry tasting (often via a candi sugar addition). That allows the flavors from the Belgian yeasts to come through, and oak tannins would certainly smother those flavors. Of course, high alcohol beers such as barleywines can be improved by adding oak flavors, even if they are not highly hopped. That’s because such beers tend to be quite sweet and the tannin bite helps make them seem drier, allowing the vanilla flavor to come through nicely.

Above all, beers using highly roasted malts (chocolate, black malts) are the prime candidates for oaking. All the flavors that can be conferred by oak tend to balance out the harshness of the roasted character and add to the depth of the beer’s palate. But again you have to be careful about which beer you pick for this. It is easy to spoil a well-balanced, low alcohol (say, 4.3% ABV) brown porter. You would be better off considering a robust porter at the top end of the alcohol range, perhaps around 6% ABV. Baltic porters are often somewhat bland and could definitely be improved by judicious oaking. I don’t think an Irish dry stout should be oaked, since its characteristic flavor is only that of high roasted malt. Cream stouts, with their typical luscious flavor from unfermentable lactose, are not likely to be improved by adding astringency from the oak. The same might be said for oatmeal stouts since the oatmeal is usually incorporated to give the beer some extra smoothness. However, that does not mean that this style cannot be improved by adding oak as long as you do so at the low end of the addition rate and residence time (say adding one spiral in 5 gallons/19 L and letting it sit in the beer for no more than three to four weeks). But finally the style that really works very well with added oak flavor is imperial stout (which includes imperial porter). These beers can carry the strong oak flavors very well, even the astringency from the tannins. In fact, since these beers are often aged over long periods, the tannins will degrade and lose their harshness (as happens in aged red wines too).


Photo courtesy of Northern Brewer

Guthrie’s Woody Imperial Stout (oak aged)

(5 gallons/19 L, extract with grains)
OG = 1.088 FG = 1.028
IBU = 68 SRM = 100+ ABV = 7.9%

8 lbs. (3.63 kg) amber liquid malt extract
3 lbs. (1.36 kg) pale dried malt extract
0.75 lbs. (0.340 kg) Belgian Special B malt
0.75 lbs. (0.340 kg) chocolate malt
0.75 lbs. (0.340 kg) black malt
18.5 AAU Columbus pellet hops (1.5 oz./43 g at 12.3% alpha acids) (60 min.)
Nottingham Ale dry yeast
1.5 oz. (43 g) medium toasted French oak cubes

Step by Step
Put the grains in a muslin bag and steep in 2 qts. (2 L) of 150–160 °F (65–71 °C) water for 20 to 30 minutes. Rinse the grains with an additional 2 qts (2 L) of hot water and transfer the liquid to a brewpot. Top up to 5 gallons (19 L) with water. Carefully dissolve the malt extracts and bring to a boil. Add hops and boil for 60 minutes. You could add the liquid malt extract towards the end of the boil if you want to, but you will have to adjust the hop rate (see “Techniques” in the September 2012 issue of Brew Your Own).

Cool to 65–70 °F (18–21°C) and pitch the yeast, preferably having previously prepared it as a 2-qt. starter. When primary fermentation has finished rack the beer onto the oak cubes in a secondary fermenter if you wish. I prefer not to add the oak at this time, but to rack a second time after about five to six days and add the cubes then. This is because I want the beer to be as clear as possible during oaking; if there is a significant amount of yeast in the secondary it will merely coat the cubes and reduce the efficiency of extraction from the oak. At any rate leave the beer on the cubes for no more than two weeks before racking it and then bottling or kegging it in the usual way.

One other step I like to do with this beer is to very lightly rinse the cubes with bourbon whiskey before adding them to the beer in the secondary. This step helps to sanitize the cubes, and also adds just a hint of bourbon to the finished beer’s flavor — a taste that goes well with this kind of stout. Some brewers like to pre-treat the oak cubes with very hot water, but I don’t like to do that as you will remove a good deal of the oak flavors you want to get into the beer.

Issue: December 2012