This is the ninth article in my series on Russian imperial stouts.
Once primary fermentation has finished, it’s time to condition — and possibly age — the beer. For the purposes of this article, I’ll define conditioning as the process of aging the beer so it loses its green character and becomes drinkable. I’ll define aging as storing the beer beyond that point, in the hopes of developing characters that can only be acquired over time. Before I discuss conditioning and aging, however, I want to describe one important test that should be done whenever you make a big ale.
Forced Fermentation Test
Big beers typically have higher final gravities (FGs) than smaller beers. Brewers new to making big ales may wonder what their final gravity should be. The apparent attenuation listed for the yeast strain should give you an idea of the range expected. And for a really quick, rough estimate, divide your gravity points by 4. This will tell you what the FG would be if your apparent attenuation were 75% (a fairly middle-of-the-road level of attenuation). For example, if your starting gravity was OG 1.085, your FG at 75% attenuation would FG 1.021.
To find out the actual final gravity you should hit — based on both the attenuative capabilities of the yeast strain and the fermentability of your wort — you should perform a forced fermentation test. To do this, take a small sample of your chilled, aerated wort. You will need enough to float a hydrometer. Mason jars can be handy for this. Pitch a grossly excessive amount of yeast to this wort, and let it ferment at fairly high temperatures (75–80 °F/24–27 °C). (If you use a mason jar, put the lid on loosely. Don’t seal it.) The wort should ferment completely in at most a few days. The FG of the forced wort is the FG your full fermentation should eventually reach. Knowing your expected FG can help you determine if your fermentation is finished, or if it has stalled or stuck.
When I started homebrewing, the standard recommendation for big ales was to rack the beer to a secondary fermenter when primary fermentation finished, and then let it condition for extended periods of time. The idea behind racking was that the beer would pick up off flavors from the yeast dying and releasing their contents. The extended periods of aging — often given as many months to a year for a beer of this size — were supposed to help the beer “mellow.”
The more recent experience of many homebrewers has been that beer left in the primary fermenter for a few weeks to a couple months doesn’t pick off off flavors. In addition, my experience has been that big ales don’t need extremely long conditioning times if the fermentation was orderly.
In the “good old days” of homebrewing, many big ales likely needed the extended conditioning times because severe underpitching was very common, and these beers retained green beer flavors and aromas for extended periods of time. I still see advice given in brewing forums today to condition beers for what I consider ridiculously long periods of time. In reality, ales — even big ales — can condition quickly if the yeast have been healthy enough to do their job.
In general, with a well-run fermentation, a big ale can condition and be drinkable in several weeks. As a general rule of thumb, I condition them (in the primary fermenter, sitting on the yeast) twice as long as the primary fermentation took. (This is probably longer than most commercial Russian imperial stouts are aged before release.) Then, I rack the beer to keg and carbonate it. If it’s still green when I sample it, it can condition further in the keg (although I rarely need to). And the same applies if you bottle it.
If you can manage it, condition the beer at a temperature below your fermentation temperature. Conditioning the beer at fermentation temperatures will work, but colder is better (down to about 50°F/10 °C). I think it’s better to condition the beer on the yeast, rather than to bottle or keg it and condition in the bottle or keg. If you condition in a carboy, you’ll avoid problems with the liquid getting sucked from your fermentation lock into the beer if you cool it slowly (a few degrees a day).
After conditioning, you can serve your beer, or you can let it age. If you’ve brewed a hoppy, “Americanized” version of a Russian imperial stout, drinking it when conditioned but still comparatively young will let you enjoy the hops, which will fade over time. If you’ve brewed to beer with the intention of aging, so that it might pick up Sherry notes or other characteristics of an aged beer, you should store it so that it has the best chance of aging gracefully. And of course, many homebrewers will take a split approach — drinking some of their beer while it is young, while setting aside a portion for aging.
Once the beer is conditioned and drinkable, separate it from the yeast. Once the beer has lost its green character, further contact with the yeast isn’t required. Rack the beer to a keg or bottles for extended aging. (For now, I’ll skip barrel aging or bourbon barrel aging.) There is a lot of conflicting information on how to age big beers. There are many opinions on the matter, but few facts based on experiments. A Russian imperial stout is high in alcohol and very dark, two factors that should improve the odds of it aging better than most beers. If you intend to age a substantial portion of your Russian imperial stout, be very careful not to splash or in any other way introduce oxygen to the beer when you package it.
Common sense should tell you to age the beer where it is protected from light, to avoid skunking. Also, if your beers are crown capped, age them upright. Caps can leak over time, and it’s at least possible that you could leach compounds out of the liners of caps if you store the bottles on their sides. If a bottle is sitting upright, the only surface the beer is touching is glass. If you’ve corked your bottles, as many Belgian beers are packaged, lay the beer down for aging, and periodically check to see that the bottle isn’t leaking.
The big question is what temperature to age the beer at. Some folks say refrigerator temperature, others — based largely on the recommendations for aging wine — advocate aging the beer around 50 °F (10 °C). Compounding the problem is that some beer drinkers enjoy some of the flavors that can eventually appear in aged beers, while others feel the beer is over the hill, oxidized, or otherwise worse for wear when the signs of aging show. Knowing how long and at what temperature to age the beer depends partly on what you want the beer to taste like. The colder you store the beer, the more slowly the beer will age.
If you don’t have much experience brewing and aging big beers, this is a good opportunity to discover what you like. Try sampling the beer when it is conditioned and write down your impression of the fresh beer. Then, store some of the beer at refrigerator temperature and some at 50–55 °F (10–13 °C). Periodically sample the beers, — and take notes to see if you can taste the beer evolving. If you can, decide if you prefer the taste of aged beer to fresh beer and at which temperature the beer developed the characters you most enjoyed. This will serve as a guide on aging subsequent batches.
In the next article in the series, I’ll show you how to mimic some aspects of bourbon barrel aging without a barrel.
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