This article is part of a series on barleywine, the second in a section on fermentation.
Yesterday, I discussed getting a barleywine fermentation started — aerating the wort and pitching the yeast. Today, after explaining one additional step you can take, I’ll discuss guiding the fermentation to it’s conclusion and conditioning the beer.
Forced Fermentation Test
A forced fermentation test is a way to predict the final gravity of your beer. To perform this test, take a small sample of wort, pitch an excess of yeast and ferment it warm. For a 5-gallon (19-L) batch of barleywine, take a sample just large enough to float your hydrometer (about 8.5 fl. oz./250 mL). Place the wort in a sanitized jar with a lid and aerate it thoroughly. Pitch about 2 tsp. of thick yeast slurry and hold the jar (with the lid loosened) at around 80 °F (27 °C), or as warm as you can manage. The sample should ferment quickly due to the high pitching rate and warm temperature. The final gravity (FG) it reaches will tell you what to expect your main batch to ferment down to. This can help you distinguish between a stuck fermentation, and one that is simply complete.
Control Fermentation Temperature
Fermentations generate their own heat. And higher gravity fermentations generate more heat than those of lower gravity beers. So, keep an eye on your fermentation temperature around high kräusen, when it is most likely to spike, and do what you can to keep the fermentation temperature steady.
It best to prepare for the possibility of kräusen overflowing the fermenter from the start. If you pitch an adequate amount of yeast and keep your fermentation temperatures in check, excessive blowoff should not be a problem if you have adequate headspace in your primary fermenter. For a 5-gallon (19-L) batch, about 2 gallons (~4 L) of headspace should be sufficient, although some yeast strains produce more kräusen than others.
In my experience, the worst “geysers” resulted from underpitched beers that suddenly started fermenting and spiked in temperature. As a precaution, install a blowoff tube and use it until high kräusen is finished; then switch to an ordinary airlock.
Finishing The Biggest Barleywines
For barleywines on the lower half of the OG range, simply holding the fermentation temperature constant should let the fermentation proceed until it reaches your target FG. It will likely slow a bit at the very end, but this is not a problem. For the biggest barleywines, you may need to help the yeast finish the fermentation. If your fermentation suddenly slows greatly, but you are short of your target FG by several points, there are two things you can do. First, let the temperature rise — at a minimum, to the highest point in there yeast’s recommended temperature range, or even a few degrees above that. Secondly, swirl the fermenter or stir the wort to get the yeast back into suspension. If you do this, but your specific gravity doesn’t budge, then you’re finished. (If you pitched an adequate amount of yeast to begin with, pitching more at this time is not likely to have an effect.)
Cold Condition in Bulk
Once fermentation has completed, let the beer sit on yeast for a few days (for the smallest barley wines) to a week or so (for the biggest). Then, rack the beer quietly to a secondary fermenter with little or (preferably) no headspace. Let the beer condition in bulk, preferably at temperatures cooler than ale fermentation temperatures. Let the beer condition for approximately 3 weeks, plus an added week for every 10 gravity points above OG 1.080. If you pitched an adequate amount of yeast, and your fermentation was orderly, this should be adequate conditioning time. Either keg your beer or bottle it at this time. If the beer still tastes green, give it additional conditioning time in the keg or bottles.
If bottling, add 1 tsp. of fresh yeast when you bottle. Use either the same yeast strain or one that does not attenuate more than your primary yeast. Keep your bottles warm — at least room temperature and preferably closer to 80 °F (27 °C) — for two weeks. Take one bottle and cool it overnight in your fridge. The next day, open the bottle to test for carbonation. If it is OK, move the remaining bottles to cold storage.
Conducting a good fermentation is key to making a great barleywine — and it all starts with pitching an adequate amount of yeast. Although some brewers view making a starter as an “extra” step, you will be glad you did when your barleywine fermentation starts promptly and proceeds without any hitches to your estimated final gravity (FG).