How long should you bottle condition your home brew? How long should you age it after bottling? There appears to be no definitive answer to these questions. But, that should be no surprise. As one brewer told me, “there are no facts in brewing.” In other words, making beer is all about experimentation.
To be sure, there are some facts. Home brewing does have specific routines you will want to follow (habits in cleaning and sanitization) regularly and precisely. There is science that explains what potential gravity may be extracted from grains and temperature ranges that work best for the mash and laws that govern the absorption of carbon dioxide into a liquid. When it comes to bottle conditioning a beer and how that will affect taste and how it applies to beer styles, well, now we are delving into the realm of subjectivity. So, here goes, some notes on bottle conditioning, carbonation, and storage.
Carbonation is one of the purposes of of bottling. Obviously, then, a crucial point is to determine what level of carbonation you want in your finished beer. There are historical levels for various styles and there are charts that can be found online. These charts will help you to determine how much priming sugar you should add to your beer to produce the right level of carbonation. As you know, there are yeast still in suspension in a beer that has completed primary fermentation. Once a charge of sugar is added to the beer fermentation begins anew at very low levels, enough to produce the carbon dioxide needed for proper head in your finished beer. The common maxim is bottle and let them sit for two weeks at room temperature to achieve carbonation. According to John Palmer in How to Brew, “small beers like 1.035 Pale Ales will reach peak flavor within a couple weeks of bottling.”
However, when your original gravity exceeds that level, when you start getting into the 1.050 and up range for stronger beers such as imperial stouts, bocks and barley-wines, it seems that longer maturation and conditioning can be beneficial. These beers have much more malt and hops than a smaller gravity beer. That complexity and higher alcohol levels need time to mellow out and blend together. Beers like that can take anywhere from a month to six months or more to reach the taste profile that you prefer.
The original pale ale in London, that morphed into what we now call India Pale Ale, was evidently aged for a year or more prior to being shipped to the colonies in India, a trip which itself took months. So highly hopped beers may benefit from longer aging. Be cautious, however, with aging beers too long. A friend told me recently of an imperial stout he sampled after aging for ten years. The beer looked more like a brown ale and the bottle was full of trub and there was no hops profile at all. Aging can be dangerous.
You also want to determine if you want to condition in the bottle or in a secondary fermentation vessel. This means that instead of bottling when primary fermentation is finished you rack the beer to another vessel and let it sit there prior to bottling. Or you can do a mixture of both. Just make sure primary fermentation is complete prior to bottling otherwise there may be some explosions.
Another consideration seems to be the yeast that is used. If primary fermentation was prolonged, it may take a little longer for the yeast to produce carbonation. Recently I did a saison which took a good three weeks to ferment out. At two weeks in the bottle the carbonation still seemed pretty light. One more week made it more drinkable and it got better each week thereafter. We are dealing with a living organism and one that will do what it wants when it wants and will continue to develop in the bottle. The best thing to do is try your beer at two weeks and determine if it needs more time in the bottle. Experimentation with storage times is the only way to determine exactly what works for your beers.
To summarize: after bottling, let your home brew sit for two weeks at room temperature to develop the carbonation levels required. Then refrigerate and enjoy. For lower gravity beers such as small pale ales, amber ales or wheat ales, this may be all the conditioning necessary. For stronger beers, such as stouts, barely-wines or IPAs, let them sit for a month and then sample. If you think it will benefit from longer maturation, let it sit. Also give thought to your cellaring temperatures. Higher alcohol level beers can be kept at around 55-60 degrees, the temperature can be lowered as alcohol levels drop.
Enjoy your experimentation and leave comments about anything I described incorrectly above or about insights you have on this stage of brewing.