The concept of bitterness can be somewhat complicated for beer consumers. It’s essential in the development of a stable beer recipe, and it is the sensation most used to describe hops, a key ingredient in lagers and ales. But consumers still largely favor crisper or sweeter malt-driven selections.
In the 1950s and ’60s, the brewing community banded together to create the International Bitterness Units (IBU) scale. The scale was the solution to an issue brewers had with the hops they were using, where alpha acids were decreasing between harvest and brewing.
“It’s always been a brewer’s reference lab measurement that you can use to check for the consistency of your own flavors inside the brewery,” says Steve Parkes, director of the American Brewers Guild Brewing School and owner of Drop-In Brewing, in Middlebury, Vermont. “As a brewery, you need to hit a number from your process so you can know your efficiencies and your losses during fermentation. You want to be able to nail the number every time.”
IBUs are measured by the amount of alpha acid derived from hops in wort or a fermented beer, which is then multiplied by 5/7. The values range from 1 to 110, and there are a variety of ways that breweries can calculate an accurate reading, including the use of ultraviolet (UV) light or via sophisticated instruments.
From time to time, brewers will add IBUs alongside other information like alcohol by volume (abv) and Standard Reference Method (SRM) score, which evaluates color.
Offering bitterness statistics to consumers helped fuel the growth of the India pale ale in U.S. markets.
“To the general beer consumer, the IBU number does not really explain much, unless you go into a great deal of length to explain it to somebody, which is almost impossible to do on a label,” says Parkes.
For some brewers, putting high IBU numbers on packaging was akin to a badge of honor or a dare for drinkers to embrace aggressive hoppiness. In many cases, this led to confusion among consumers or even a reluctance to try a particular beer.
An IBU can be helpful to indicate if a beer is within accepted style guidelines. American light lagers typically strive for no more than 10 IBUs, so one that boasts 35 would be irredeemably bitter. However, an extra special bitter (ESB, or English-style pale ale), that checks in at the same level will have great balance.
Studying up on various styles, from imperial stouts to doppelbocks, Berliner weisse and saison, will help calibrate a palate to expect certain levels of perceived bitterness and can square the numbers between taste buds and the brain.
Bottom line: Unless you are a brewer, it does not do much good to get hung up on an IBU number.
Published: December 14, 2021