Earlier this week I told you that, summer be damned, now was the time to buy up new imperial stouts — and keep them in your cellar. But like every good rule, there are exceptions. Hoppy beers are generally not suitable for aging; the compounds responsible for hops’ fresh, citrusy flavors and aromas are highly volatile, which means they’ll deteriorate if you wait to drink them with your plum pudding.

Imperial stouts tend to be lightweight in the hop category, favoring heavy doses of rich, chocolaty malts, but the occasional hoppy imperial stout is an eye-opening mix of both worlds, and is best consumed fresh. Two to drink now are Goose Island Night Stalker and Stone Imperial Russian Stout. The former begins life as a Bourbon County Stout sans the bourbon — rather than sleep in a barrel, the base beer gets dry-hopped with Mt. Hood and Simcoe hops for a roast-coffee aroma that’s less than subtle.

Stone loves hops almost as much as in-your-face marketing copy, and their imperial stout is true to their creed, its clean bitterness rounding out the beer’s dark-chocolate profile. By contrast, I tried aging an IRS for a year, and it came out soft, the dark chocolate mellowed to more of a health-food carob level. Some of my grillmates liked this — and any brewery is going to recommend you age their strong stouts, hoppy or not — but I still prefer the fresh versions for these two. Then again, if you start aging now, in a year you could have empirical evidence to prove me wrong.