Editor’s Note: With Tim Carman away on vacation, Young & Hungry invited Greg Engert, the beer director for the Neighborhood Restaurant Group, which includes ChurchKey and Birch & Barley, to blog in his absence.

For today’s blog post, I am following the lead of the Beerspotter and the Lagerheads and taking a question from the “Dear Abbey” pile. Josh wants to know what beers cellar well how long said beers should be cellared?

Here goes…

Like wine, many—if not most—craft beers are not dispensed when green, but have in fact been aged for a period of time prior to release for immediate drinking or further aging; many beers mature before public release in the tank, barrel or bottle, some for a few weeks and some for many months. In this way, the beer’s flavors have evolved positively enough to be deemed ready for immediate appraisal. A few beers will additionally mature to proffer new and compelling flavors to the drinker, but it is important to note that they will rarely require such maturation; age-worthy wines—on the other hand—demand a laying-down, for they are disagreeably rough in their adolescence.

While beers are not so callow when young, some retain an aptitude for transformative potentiality. More simply, some deteriorate in delicious ways.

The aging process effects chemical changes in all beers. Gradual, subtle alterations in flavor result in beers that taste very different than they once did. This is not to say better, but new; and these flavor nuances are intriguing because they are unattainable by any other means than maturation.

So what beers can benefit from the nuances imparted by degeneration? Only those that can maintain control over, and amalgamate, attributes imparted by a (hopefully) slow and steady decline.

The pertinent issue with regard to aging is the means by which the beer can tame the influx of disintegrating agents. Oxygen will infiltrate beer over time, so the best brews for positive maturation will limit such impregnation. Darker beers possess an antioxidant effect garnered from the heavy kilning of their malts and/or grains, and this allows them to defend against the more negative effects of oxidation. Beers that are bottle-conditioned will also deny the adverse effects of oxygen due to the creation of additional carbon dioxide as fermentation continues; this CO2 will keep O2 from too immediately rearing its ugly head (refermentation also contributes additional layers of flavor that can accentuate a brew’s complexity). And the larger the bottle, or keg, the better the chances for the beer to resist full-blown oxidation. The ullage, the unfilled space in the container of liquid, will be smaller by comparison to the amount of beer present, and thus the oxygen that may interact with the brew will precipitate fewer—and far less extreme—transformations.

Oxygen has the ability to give beer an unpalatable cheesy and cardboard flavor. Lighter colored brews, beers contained in smaller formats, and those without bottle-conditioning offer a more welcoming environment for negative oxidation. Those with a darker complexion, refermentation in the bottle, and smaller ullage-to-liquid ratios can pick up a palatable vinous character; as oxidation happens slowly and over a longer period of time, it can add pleasing sherry-like, raisiny, caramelized, toasty, and nutty flavors and aromas.

Oxygen’s influence is not limited to oxidative effects, but can also heighten the possibility for negative bacterial infection. On account of this distinct possibility, strong beers—and those with higher hopping rates—age quite well, as alcohol and hops are natural preservatives. (Also, high alcohol beers are not as susceptible to the negative affects of bacteria. It is more difficult to detect off flavors imparted by bacteria in a robust, strong beer than it is in a delicate beer that readily reveals the minutest of flaws… the same can be said for the subsuming of flavors associated with oxidation). I am not advocating the maturation of deliberately hoppy brews though, as the fresh hop aromatics and tastes are what drive the flavor intensity of such brew. The true pleasure of Imperial IPAs and the like is the fresher aromatics of hops; when aged, they lose the hop bouquet that is the source of many of their pleasures. Beers that showcase a multitude of flavors beyond the primacy of hop, while still having a nice hop presence, will do well with a bit of age (think of American-style Barleywines, for instance).

Acidity, especially the lactic variety, also tends to create a chemical environment less welcoming to micro flora known for the production of disagreeable flavors. And acidity, along with other intense tastes—like bitterness (from hops and/or roasted malt/grain) and sweetness (from malt and/or the presence of alcohol)—will mellow as a beer matures. This mellowing allows for the incorporation of bourgeoning flavors brought on by maturation: those that have lain dormant, previously overwhelmed or newly developed; the result is an altogether distinctly new character in the beer.

Like oxidation, there can be some positive effects of the bacterial interplay in beer. With proper preservative properties, only the more palatable acidic and funky flavors associated with wild yeasts and bacteria should evolve. These effects may be the result of infiltration during storage, or arise from latent microflora—initially engendered during brewing and fermentation—that have only awakened during the aging process. A bit of infection is not terrible for aging beer; however, it must be subtle enough to join—as with oxidative effects—in the mélange of aged tastes and aromas. If it is out of balance, than the beer has turned.

When seeking to inspire positive flavor evolution, it is important to keep the brew at cellar temperatures ranging from 50-65 F with little fluctuation. This temperature range keeps the aging process slow and preserves the flavors longer; also, warmer temperatures may speed up refermentation and CO2 production, pressuring the cork, cage or cap to come loose and allow too much oxygen and bacteria to infiltrate (warmer temperatures also encourage the activity of any bacteria that may arrive). It is also important to store beer in the dark as light may strike and—by a chemical interaction with hops—encourage skunky flavors.

So what beer styles are best for maturation? If the conditions outlined above are kept, I find that stronger, darker brews are always the best bet; stronger beers with paler appearances tend to become too quickly overwhelmed by oxidation and possible bacterial activity. Higher hopping rates, if not the initial and intentionally dominant flavor nuance for the beer, as well as more intense acidity can also recommend a brew for keeping. Bottle-conditioning is not required, but is beneficial and also promotes a maturation effect unseen in the cellaring of wine. Keeping these factors in mind, here are some styles I do not hesitate to age or to purchase with some age on them:

• American & English Barleywine
• Stronger Doppelbock & Eisbocks
• English Old Ale
• Scotch Ale/Wee Heavy
• Baltic Porter
• Imperial Stout
• Wheatwine
• Weizenbock
• Belgian Strong Dark Ale & Quadrupel
• Stronger Wild Ale including Flemish Oud Bruin & Flanders Red Ale
• Gueuze & Traditional Lambic

It is hard to say how long one should age a beer. Before the moment of turning (when the beer is no longer appetizing), flavor compounds are breaking down and reattaching into larger compounds of dazzling complexity. After a certain point, these compounds are overwhelmed by the effects of over-aging that result from higher oxidation and infection. Past its peak moment, the malt and hop character thin out, oxidation can take on a papery or cardboard character, and acidity is no longer pleasing.

But what is the peak? As I mentioned earlier, beer does not need to be aged, so it seems misguided to try to determine when it needs to be drank. Vintage beer is a relatively new phenomenon, so—unlike with wine—we are not spoiled with years and years of research as to when certain styles are best consumed. And I don’t know if we really need this “data.” Taste is ultimately subjective, and beer tastes great at countless points of deterioration. Beer enthusiasts are beer drinkers first, and I find it unlikely that we will ever lose interest in the drinking long enough to gain a posturing stance of supposed objective age-evaluation. Will my bottle of Islay Scotch Whisky Barrel-Aged Beer Geek Brunch Weasel astonish in five years? I am not sure, but I can only hope it would have continued to impress as it did last night—when I savored every drop.