Lesson 8: Et Tu IBU?

A contentious topic of conversation in the beer world is whether IBU ratings need to be accessible to the beer consumer. Many beer drinkers use the IBU scale as a reference tool, so they can judge the relative bitterness of a beer. On the other hand, most brewers argue against publishing IBUs, as they are often based on rough calculations and tell little about how bitter a beer will actually taste.

An IBU or International Bitterness Unit is a gauge of a beer’s bitterness and is measured in parts per million of isohumulone (bitter alpha acids). The scale starts at 0 and is open-ended in theory, but because bittering compounds are only somewhat soluble in water, there is an upper limit to how many IBUs you can pack into a beer.

Properly testing IBU levels involves a spectrometer that measures the amount of isohumulones that can be extracted from a beer. The process of measuring a beer’s bitterness is relatively simple, but the equipment is very expensive. Most craft brewers don’t own equipment to accurately measure bitterness and will instead calculate approximate values based on a formula.

Measuring IBUs is primarily used as a quality control tool for brewing, not a descriptive one for consumers. Most brewers aren’t trying to achieve a specific IBU rating to fulfill any particular style requirements. Instead, they are using IBUs as a gauge for consistency in hopping, especially when brewing multiple batches of a beer, as hops are constantly changing and will degrade over time.

While some drinkers refer to IBUs to determine bitterness, measuring IBUs does not take a beer’s perceived bitterness into consideration. Perceived bitterness includes all other factors that affect our perception of bitterness including malt sweetness, yeast characteristics and body of a beer.

As many brewers will argue, and most of us can agree, our perception of bitterness is more relevant to how we taste beer than the parts per million of isohumulones found in it. As beer consumers, we need to stop limiting our choices based on IBUs and instead identify the qualities that we are looking for in a brew. When it come to new flavours we just have to “give brews a chance.”