Which is more bitter, an export stout, a pale ale, or an English barleywine? We have ways of measuring certain constituents in beer, and these translate into calibrations. To assess bitterness, brewers measure how much of a hop's alpha acids are present in the beer and produce a standard measure of bitterness ("international bitterness unit," or IBU). But of course, where flavor is concerned IBUs are relative measurements; malt sweetness dulls the clean expression of bitterness. The bigger the beer, the more hops are needed just to maintain a consistent level of perceived bitterness. So, if I told you that each of the beers had 50 IBUs, this would give you a sense of which is going to taste more bitter: the barleywine will be sweetish, the export stout dry and crisp, and the pale ale vivid in direct hop bitterness.
But you knew all this.
Last night, I was enjoying my first Hop Henge, a beer that has managed to elude me these past four years (a level of negligence that demands its own post). The bottle lists the beer at 95 IBUs, which, even in a beer with 8.8% alcohol, is a tremendous number. Yet it misleads. Hop Henge was absolutely saturated with hops, with additions that began in the grist mill (!) and continued on through dry-hopping. The effect is fascinating. While no one would say Hop Henge isn't bitter, it's rather much more--a leafy green beer so infused with hops you almost have an allergic reaction (in a good way, of course).
We know that many things affect the perception of bitterness--in addition to malts, the level of carbonation, the specific hop variety used, and yeast attenuation all play a role. Now I wonder: can hops themselves affect the perception of bitterness? In Hop Henge, Deschutes used just about every element of the hop--the acids, oils, pollen, even the inert, cellular material. As a consequence, the perception of bitterness is colored by a staggering spectrum of other flavors and aromas. By adding hops at various points throughout the brewing process and extracting more hop elements, are breweries also changing the way we perceive bittereness? I think so.
More and more, breweries are infusing their beers with hops at all stages of brewing. As they do, the measure of bitterness becomes a less valuable tool in predicting flavor than knowing the method the brewery used to hop the beer. I recall when I first began to see dry-hopping mentioned, maybe 15 years ago. It was really useful information. Perhaps its time to invent a term to suggest this use of hops from mash tun to fermenter. "All Phase" hopping, say. Anyway, yet another wrinkle in the appreciation of our favorite ingredient--and a welcome one.