The Real Story of IBUs
by Pete Lamburro

IBUs — international bitterness units — has assumed new importance in the craft beer world.
Simply put, they 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 Web sites
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, 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 which just about rendered the number meaningless.

Touting the number of IBUs in a beer may be good marketing but it's not very sound logic. For
example, Palate Wrecker is named for its ability to numb your taste buds, so what would
a 1,000-IBU hop monster do? Burn a hole in your tongue?  Actually, the taste threshold for
IBUs is around 100 meaning anything over that won't register with you so what's the point?

But there's more to consider about that IBU number. Don’t believe everything you read on a
label, Most values on craft beer bottles are not analytical measurements; they’re calculations,
or if you prefer, educated guesses.  Since there is no law governing the accuracy of the
number  consumers might not want to make it a main criteria in their beer selection.

But not only might the number be misleading there's another factor to consider. The
iso-alpha acids would reach a saturation point long before the 1,000 (or even the 200) mark
is reached. What’s more 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.

It's important thing to remember  that when evaluating IBUs.- Iso-alpha acids alone won’t
help you attain hop bliss. It is generally accepted that there are 300 to 400 compounds that
have been identified in the essential oils of hops; in fact, some scientists say  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. So a simple
number can't tell you a beer's true hop taste.  Also consider that many brewers add more
malt to balance a large IBU number toning down the bitterness sought by hop heads.
Bitterness is relative to the amount of malt in a beer. The more malt in a beer the sweeter the
beer, and the sweeter the beer the more bittering acids are needed to balance that sweetness.

Rather than chase IBUs ever upward many breweries are finding other ways to romance the
hop. One of the most prevalent ways is to us dry hopping which greatly increases perceived
bitterness.  In dry-hopping, the hops are added during or after fermentation. Those late
additions enhance the hop perfume but don’t add an iota to the IBU level. - SPECIAL REPORT
Bitterness in Beer
Commercial Beer IBU Ratings
Click to enlarge