It’s nice to think we all improve with age.

Our favorite malt beverage is no exception — to a point. Uncap a beer before its time and you’ll pour a lackluster, hazy, flat liquid, not the sparkling brew you’ve come to expect. The beer is still young; give it time.

On the other hand, old beer is, well, old beer. That’s why homebrewers should always ask the age-old question: Is my beer too young, too old or just right?

All beers require at least a brief aging or “conditioning” period. During this critical time, three important things happen: The beer carbonates and clarifies, and the flavors mature.

Different styles have different conditioning requirements. This is dictated by the yeast strain used, and also by fermentation temperatures. For most ales, two to three weeks is sufficient, although some brewers swear that four weeks is the minimum requirement. (Of course, many impatient homebrewers have consumed their entire batch by then.) Some lagers and strong, high-gravity ales — such as Scotch and Trappist ales — benefit from much longer aging periods. More about these styles later.

Homebrewers may think the aging process begins once beer has been bottled or kegged. Actually, the aging process starts with fermentation, when flavor development begins. As yeast flocculates, the beer starts to clarify. And as beer sits on old, dead yeast, it’s already beginning to grow old. Because old yeast can impart off-flavors to your young beer, transferring to a secondary fermenter is recommended, especially if you’re not planning to rack for a while.

Slow Lagers and Speedy Ales
Most homebrewers associate aging with lager beers. In fact the German word “lager” means “to store.” Traditionally, lagers are aged for up to three months at 32° F. These conditions are considered ideal to accomplish the goals of maturation.

In today’s competitive beer market, few breweries can afford to age beer for that long. With modern advances, fine lagers can be created in three weeks. For example, filtering beer removes yeast and protein molecules, eliminating the need to wait out a long clarification period. Manipulating temperatures shortens the time needed for flavor development. Homebrewers can also imitate these techniques.

Most ales fermented at 65° F or warmer will be drinkable after a short fermentation and conditioning period, as little as two weeks. The minimal aging period — and rapid turnover — makes ales a popular and financially sound choice for most brewpubs.

Is there an advantage to aging most ales? Yes, but aging times for great ales usually don’t exceed two to three weeks. In fact, over-aging can have negative effects. For instance, yeast autolysis can impart a meaty, brothy  flavor to your beer. Also, if you leave too much headspace in the bottles at filling, the beer will become oxidized before you have a chance to enjoy it.

There are some notable exceptions. Scotch ales, for example—unlike traditional English ales—are conditioned at lower temperatures and for longer periods of time, like lagers. The same long aging time holds true for barleywines, Trappist ales, and any other high-gravity ale. Cask-conditioned ales, which are fined and served at slightly warmer temperatures to enhance clarity, are also exceptions, although the aging period is still short in comparison (about seven to 10 days).

The ABCs of Aging  
Carbonation: While breweries age their beer in tanks prior to bottling, a homebrewer can mimic these conditions by using kegs. Five-gallon Cornelius kegs are easy to come by and are available new or reconditioned. Beer that has been kegged can be force-carbonated by injecting bottled CO2 into the keg.

Bottled beer must be primed using corn sugar, dry malt extract, or even honey. Adding sugar to the fermented beer will cause the remaining yeast to become active, gobbling up this new food source and producing CO2.

Clarification: During this stage of the beer’s life, clarification also occurs. As the beer sits quietly, the solid particles still suspended in the beer, including yeast and large protein molecules, will eventually settle to the bottom. This process, like natural carbonation, does not happen overnight but over the course of several weeks.

Maturation: Aging beer also serves to remove undesirable young or “green” beer flavors, the three most common of which are diacetyl, acetaldehyde, and hydrogen sulphide. Diacetyl, which has a buttery taste, is produced during primary fermentation. The higher the fermentation temperature, the higher the diacetyl level.

Acetaldehyde, which produces a green-apple flavor, is also produced early in fermentation. Warmer fermentation temperatures, a high pitching rate, and poor wort aeration also contribute to this off-flavor. Both diacetyl and acetaldehyde are reabsorbed by healthy, active yeast, which in turn produces ethanol.

Hydrogen sulphide, which has sulphury, rotten-egg smell, also diminishes as beer matures. One way to reduce these characteristics is to ferment at cooler temperatures, although they will be removed more rapidly at higher temperatures. Hydrogen sulphide is also vented from the beer if the headspace of a lagering tank is periodically purged during secondary fermentation.

Maturation also fixes flavors such as alcohol and esters. Fermentation and conditioning temperatures will, again, be determined by the yeast. Generally, ales are conditioned at room temperature, around 65° F, while lagers are conditioned at about 45° F.

The aging process is also a good time to experiment with dry hopping or other techniques. If you’re feeling adventurous, you might consider the old process of oak aging. Your best bet is to use a small, very clean wooden barrel in good repair (with no leaks.) Or you can buy wood chips and introduce them into your keg. Keep in mind that not all beers are suited to oak aging. Dark, malty beers are a better choice than lighter-bodied beers. You should sample the beer at frequent intervals to monitor its progress.
    
In Good Taste
Monitoring your beers for oak level is not the only reason to check the progress of your beer. There will be a window of opportunity during which your beers will taste their best.

You’ll never really know how your beer’s doing until you open a bottle and try it. Young beers may taste green and appear hazy. Old beers may taste meaty or yeasty and have oxidized notes, which are similar to cardboard or sherry. Properly aged beers taste just right.

Gretchen Schmidhausler is head brewer at the Ship Inn in Milford, New Jersey.