Beer lovers nowadays subsist on a steady diet of alphabet soup.
They need to distinguish between ESBs (extra special bitters) and IPAs (India pale ales), and to know a beer's ABV (alcohol by volume). Home brewers grapple with such abbreviations as OG (original gravity), FG (final gravity) and SRM (Standard Research Method, a system for gauging color).
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Now that experimentation seems to be shifting from Belgian styles to hoppy ales, the IBU -- international bitterness unit -- has assumed new importance. IBUs primarily measure iso-alpha acids, the chief bittering compound in hops. The scale was devised in the 1950s to help brewers keep their recipes consistent from batch to batch. Today, IBU levels are often trumpeted on beer labels, brewery websites and supermarket placards, a way of bragging that my beer is bigger than yours.
The measurement does help consumers compare one style with another. In American-style lagers such as Budweiser, the IBU level (typically 12 or below) barely pokes through the threshold of taste. A hoppy Pilsener, at 20 to 30 IBUs, will have a pronounced bitter character. An IPA, at 50 to 60 IBUs, should slap you across the face with hops.
As a result of the public's craving for ever-hoppier beers, craft breweries are taking IBUs into the stratosphere. El Dorado Single Hop Imperial IPA, from Flying Dog Brewery in Frederick, Md., measures 70 IBUs. Enjoy By 02.15.13 IPA, from Stone Brewing in Escondido, Calif., clocks in at 88. Palate Wrecker, from Green Flash Brewing in San Diego, measures "in excess of 130 IBUs," according to brew master Chuck Silva (although he admits the lab tests weren't really calibrated to measure concentrations that high).
Some claims verge on the absurd. BrewDog in Fraserburgh, Scotland, a few years back released Nanny State, a supremely unbalanced brew that in its original version measured 1.1 percent alcohol and a purported 225 IBUs. Denmark's Mikkeller brewery once marketed an imperial IPA called 1000 IBU.
If Palate Wrecker is named for its ability to numb your taste buds, what would a 1,000-IBU hop monster do? Burn a hole in your tongue?
Don't believe everything you read on a label, cautions Mitch Steele, brew master for Stone. "Most values on craft beer bottles are not analytical measurements; they're calculations," he says.
The iso-alpha acids would reach a saturation point long before the 1,000 (or even the 200) mark is reached. What's more, adds Steele, a beer can shed 25 to 30 percent of its IBUs during fermentation. As the pH drops, some of the acids turn to solids and have to be strained out.
More important, iso-alpha acids alone won't help you attain hop bliss. "There are 300 to 400 compounds that have been identified in the essential oils of hops," says Thomas Shellhammer, professor of fermentation science at Oregon State University. "There could be as many as a thousand."
Those essential oils distinguish one hop strain from another, imparting the aromas we describe as spicy, floral, citrusy, resiny and grassy.
Stone's Enjoy By 02.15.13 IPA (the name refers to the pull date, a way of stressing that hoppy ales are best consumed fresh) contains 11 types of hops. "I get a nice citrusy flavor, a bit of garlic dankness and a big batch of tropical fruit," says Steele.
Rather than chase IBUs ever upward, breweries are finding other ways to romance the hop. "What people don't realize is how much perceived bitterness comes from dry-hopping," says Sam Calagione, president of Dogfish Head Craft Brewery in Milton, Del. In dry-hopping, the hops are added during or after fermentation, on the cold side of the brewery. Those late additions enhance the hop perfume but don't add an iota to the IBU level.
Breweries are also experimenting with new hop strains and new combinations. They're adding fruit and spice. They're barrel-aging their IPAs. Dogfish Head is about to introduce Rhizing Bines as part of a promotion dubbed "A Hop Eclipse Now" that will see the brewery host more than 50 beer dinners nationwide. The new double IPA includes a hop known only as Number 644, obtained from Sierra Nevada Brewing, which adds unusual "earthy, melon-rind, tropical notes," according to Calagione.
In March, Dogfish Head will launch still another IPA, Sixty-One, which marries hops with Syrah grape must. "It's equal parts vinous and citrusy fruitiness," Calagione says.
Not to be outdone, Green Flash this year will roll out six new draft-only IPAs under its "Hop Odyssey" program. A black IPA with piny hops is planned for February. Coming in August is Cedar Plank Pale Ale. The wood aging adds "a peppercorn spiciness and a tannic, dry mouth feel" that augments the hops, promises the brewery's news release.
Boston Beer this month will introduce Samuel Adams Double Agent IPL, an "India pale lager" that combines the fruity blast of Pacific Northwest hops (usually reserved for ales) with the smoother finish typical of lager beers.
Haphazardly elevating IBUs can create a harsh, unpleasant brew. It might also be a futile endeavor, as our sense of taste can handle only so much. Shellhammer at Oregon State can tell you the lower limits for perceiving hop bitterness: They range from about five IBUs to 13, depending on the individual. But he can't peg an upper limit because the research hasn't been done.
Silva speculates that once you get past 100 IBUs, your palate loses its ability to detect further gradations in bitterness. Steele estimates that the limit is reached somewhere between 70 and 80 IBUs.
Identifying that ceiling is important, insists Steele. Otherwise, "you reach a point where you're wasting hops: You're getting nothing out of them."