Aging Beer in a Keg (How To Do It & Potential Issues)

Many things get better with age. Cheese, wine, pickles, self-confidence, and a surprise to some: beer. How does a homebrewer achieve keg-aged beer?

Beer can be aged in either bottles or kegs, but there are certain advantages to choosing the keg, including the ability to test the beer as it ages, and the relative ease of removing oxygen from the container. Ensure the keg is properly prepared as your beer will oxidize over the months of storage if the air is not completely removed from the keg.

Keep reading to learn how to age beer in a keg, what you should do, and what to watch out for.

Can you age beer in a keg?

So you’ve decided to try aging beer in a keg because you don’t want to start bottling. Or perhaps you’ve heard that beer ages better in large quantities as opposed to separate bottles. Whatever the case, a keg is all you’ll need.

Homebrew beer of any style can be aged in a keg at home, however not all beers will be improved by aging. Hop-focused beers tend not to change very much during the aging process, while malt-focused beers will develop depth and richness over time.

Aging can introduce new flavors and mellow existing ones in beer. These new flavors and harmonies range from gross spoiled flavors to rich new flavor profiles. It all depends on the style of beer, length, and method of aging.

Beer history buffs likely know that this is how the Russian Imperial Stout had to be a high ABV for the beer to survive the long trip from London to Saint Petersburg, it had to have a higher ABV. This helped the beer age gracefully rather than spoil.

These days it is mostly done for effect rather than out of necessity by beer aficionados, craft brewers, and the curious. Beers are aged in liquor barrels, most commonly bourbon, to add flavors from the barrel. Other beers are brewed to be aged almost like a wine.

How long does beer need to condition in a keg?

Just like different wines need different aging times to achieve their full potential, beers need a range of time to condition. 

If aging to carbonate, the beer will need a week or two depending on the method used. If aging to develop the flavor profile, the beer will need at least a month. As a rule of thumb, the more ABV or complexity the longer you can age the beer. 

Notice I said can, not should. Aging beer is a matter of taste. Even the beers that are brewed to be aged can be drunk without aging. It may not taste as good, but it would give you a good idea of where the beer starts.

This is something that would be helpful when figuring out how you like your beers aged. In pursuit of this, it’s handy to keep a beer journal so that you can experiment with beer styles and aging time to find your preferred maturity.

The benefit of aging beer in a keg is that you can taste-test as it ages. Start with a month then taste every week or so. Write your thoughts down for each testing so that you can compare when you’re happy with it.

Lower ABV and hoppy beers should be consumed as soon as they’re finished carbonating. In almost all cases, these beers do not develop positively with age. 

Want to learn more about bottle conditioning and carbonation? Check out this article!

Can beer oxidize in a keg?

No matter what style of beer you’re aging, it can go wrong if it oxidizes.

Packaging beer in a keg is a great way to reduce the chance of oxidation, but it can still occur. Even when you follow oxygen purging procedures with fully functional equipment there is still the chance of oxidation from dissolved oxygen.

Potential oxygen sources include:

  • Packaging headspace
  • Improperly sealed/leaky valves
  • Leaky transfer tubing
  • Dissolved oxygen
  • Overaeration and underpitching

That said, if done properly, kegging will greatly reduce the chance and rate of oxidation. Headspace oxygen for example is one source of oxidation that can be almost entirely eliminated.

How to age beer inside a keg

Aging beer in a keg requires some setup but is primarily an exercise in patience.

To age beer in a keg, you must purge the keg of oxygen, transfer the beer into the keg without introducing oxygen, store the keg in a cool, dark place, then let the beer age for at least a month.

Purge the oxygen & transfer beer

The first step is the most involved though without it your beer will likely oxidize and won’t age well.

To purge the oxygen from your keg:

  1. Fill your keg with a sanitizer such as Star San. This will both sanitize and displace oxygen.
  2. Swap the in and out posts. This allows you to complete the next step.
  3. Hook up CO2 to the out post and push the sanitizer out through the in post. A low PSI should be sufficient.
  4. Fill the keg with your beer through the out post.
  5. Ensure all valves are properly sealed.

This process can be done with an empty keg if you have already sanitized it. Instead of forcing sanitizer out, you will be purging the oxygen directly. You will know you’ve purged the oxygen when there is a strong CO2 smell coming from the keg.

Once the oxygen has been purged there are a variety of ways to rack your beer. Any method will work as long as it doesn’t add oxygen back into the keg. A siphon tube or the liquid out post would work well.

Find a place for storage

At this point, you’ll need to decide where you’re going to store the keg.

Anywhere that doesn’t get sunlight or experience temperature fluctuations would be best. The temperature should be no higher than 60°F. High ABV beers should be aged somewhere between 55-60°F while lagers and the like should be around 40-50°F.

When you have a good location picked out, you should store the keg sitting upright. You can either keep the keg hooked up to CO2 or store it on its own. This depends on whether you carbonated the beer before aging or are carbing at the same time.

Let time take over

Now it’s time to hurry up and wait. Again, the aging time depends on what style of beer you have. Some can be aged as long as a couple of years. 

Your best bet is to channel your inner scientist and experiment – and test regularly! However, there are some general guidelines to get you started:

  • Hoppy flavors will fade very quickly so IPAs should not be aged for long if at all. In general, vibrant flavors will mellow over time. In beers where this is the main flavor style, their main contributor will be muted.
  • Malt-centric beers will develop new notes that will often add richness to the beer.

Beyond that, the world is your oyster. Good luck!