exBEERiment | Brewing With Wood: Oak Infusion Spirals vs. Oak Cubes In American Barleywine

Author: Phil Rusher

Brewers have been producing beer with wood character for eons, in fact the first beers ever intentionally produced were almost certainly fermented in wooden vessels. Nowadays, the most common material to ferment in is stainless steel, and brewers looking to add the essence of wood, usually some form of oak, often do so once fermentation is complete. On the commercial scale, brewers tend to rely mostly on transferring the fermented beer to oak barrels where they pick up the desired characteristics over a period of aging.

Other wood options exist for those who aren’t interested in storing barrels or tend to make smaller batch sizes. Invented by Russell Karasch of The Barrel Mill as a means of conveniently imparting oak character to beer and wine, Oak Infusion Spirals are relatively short lengths of different types of oak with various levels of toast that can easily be added to the fermenter, the spiral cut maximizing surface area and thus contact with the beer. Another popular option are oak cubes, which are made from barrel staves that have been dried over time before being chopped into small cubes.

I’m definitely a fan of wood-aged beers, and while my experience brewing them is relatively limited, I’ve relied mostly on cubes, to good effect. Admittedly, my thinking had been that oak is oak, and that the form it came in likely didn’t have much of an impact. After hearing differing opinions from other brewers, many claiming positive results using spirals, I decided to test it out for myself.

| PURPOSE |

To evaluate the differences between beers made with either oak spirals or oak cubes.

| METHODS |

While any style can be designed to work well with oak character, it’s most common in bigger beers, which is why I went with an American Barleywine for this xBmt.

…at the Pace of an Entmoot

My first order of business was collecting the RO water for this 10 gallon/38 liter batch, which I did a few days ahead of time.

A day before to brewing, I made a single large yeast starter of Imperial Yeast A01 House.

Later that day, I weighed out and milled the grain in preparation for the following morning.

On brew day, I heated the previously collected RO water, which was adjusted to my desired profile, then mashed in to achieve my desired temperature.

While waiting on the mash, I prepped the kettle hop additions.

When the 60 minute mash rest was complete, I collected the sweet wort then proceeded with a 60 minute boil, adding hops added at the times stated in the recipe.

When the boil was finished, I took a refractometer reading showing the wort hit my target 1.093 OG then evenly split it between two sanitized Brew Buckets.

The filled fermenters were placed in my chamber controlled to my desired fermentation temperature of 68°F/20°C, at which point I split the yeast starter between them.

After 11 days, it was time to add the wood. Per the crew, it was decided to keep the weight of each type of oak constant between the batches. Being that the mass of two oak spirals was 104 grams, I used an equal amount of cubes. To reduce the risk of contamination, I prepared the oak by boiling it for 15 minutes.

With the wood sanitized and separated from the water, I gently added them to the beers.

I let the beer remain in contact with the oak for 6 weeks, at which point I took hydrometer measurements confirming both had reached the same FG.

After sufficient aging on wood, I proceeded with racking each of the beers into a sanitized and CO2 purged keg.

The filled kegs were placed in my keezer, burst carbonated, and left to condition for a week before I began serving them to tasters.

| RESULTS |

A total of 22 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of beer aged on oak spirals and 1 sample of beer aged on oak cubes in different colored opaque cups then asked to identify the unique sample. While 11 tasters (p<0.05) would have had to accurately identify the unique sample in order to reach statistical significance, 12 did (p=0.013), indicating participants in this xBmt were able to reliably distinguish a Barleywine aged on oak spirals for 6 weeks from one aged on oak cubes for the same amount of time.

The 12 participants who made the accurate selection on the triangle test were instructed to complete a brief preference survey comparing only the beers that were different. A total of 4 tasters reported preferring the beer made with oak spirals, 2 liked the oak cubes beer more, 5 had no preference despite noticing a difference, and 1 reported perceiving no difference.

My Impressions: Out of the 5 semi-blind triangle tests I attempted, I chose the odd-beer-out 4 times. To me, the beer made with oak spirals had much more up-front oak flavor and aroma, so much so that it was a bit off putting at first. Interestingly, I also perceived it to have more grapefruit flavor. That said, both beers were very drinkable despite being very woody and very boozy.

| DISCUSSION |

Various barrel alternatives are available to those brewers who may not have the space for an actual barrel, or who just want to hasten the wood-aging process. Both Oak Infusion Spirals and oak cubes are inexpensive options that are known to impart desirable wood characteristics to beer, though despite their similarities, some claim they contribute distinct differences. Indeed, tasters in this xBmt were able to reliably distinguish a Barleywine made with spirals from one made with the same amount of cubes.

A common topic when it comes to using barrel alternatives is surface area, which may provide a plausible explanation for these results. Whereas oak cubes have 6 flat surfaces that maintain contact with the beer, Oak Infusion Spirals were specifically designed to increase surface area such that more of the wood touches the beer during aging. What’s more is that there is some degree of penetration of beer into the oak, which can be difficult to account for when considering surface area to volume ratio in both spirals and cubes. On the other hand, despite both types of oak being of the same region and toast level, they were not produced by the same manufacturer, which may also have contributed to the perceptible difference.

More often than not, I’m looking to shorten the turnaround time of beers I brew, and while I expect wood-aged beers to require some aging, oak alternatives really do seem to reduce the time needed to extract the desired characteristics. While both beers in this xBmt had noticeable levels of oak, I had a slight preference for the one made with oak spirals and will be using them in the future.

If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!

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