I is for IBU
I is for IBU – part 9 of our A to Z guide to craft beer terms.
Like em’ or hate em’ – hoppy, bitter beers are where it’s at on the international craft beer scene. With the rise in popularity of IPAs, “hop bombs” (as they’re known) are becoming more and more common place as a staple of many breweries worldwide.
And while Devil’s Peak Brewery’s King’s Blockhouse IPA is quite tame by American standards, it’s enough to make most craft drinkers raise an eyebrow our two after their first sample. Not only do you get bold, punchy, hoppy flavours and aromas (including citrus, grapefruit, and pine), you’ll also get a nice smack in the face from the bitterness that accompanies these styles.
Where does this bitterness come from? Do all hops add the same bitterness? Can it be measured? I’m glad you asked.
Hops contain organic compounds called alpha and beta acids. You get most of the bitterness from alpha.
In these alpha acids there are five main compounds – humulone, adhumulone, prehumulone, posthumulone and cohumulone. During the brewing process, through boiling, they are degraded to form iso-alpha acids. These compounds are more soluble, and contribute much of the bitterness associated with beer.
Beta acids impart a harsher bitterness to beer, but they’re insoluble, so what they end up contributing to the end product is much lower.
Both alpha and beta also boast antiseptic properties which help beer stay fresh and bacteria free for longer. I’m sure you can imagine how helpful this was back in the day when things weren’t exactly . . . sterile.
So brewers, knowing the alpha and beta acid levels of different hops, are able to select the varieties that will best compliment the style of beer they’re brewing. Pretty cool!
For reference, a scale has been developed to measure the bitterness in beer. It allows brewers to aim for a desired number and consumers to know what they’re getting into.
IBU or International Bittering Units are the unit of measurement used to express a beer’s bitterness as milligrams of iso-alpha-acid of beer (remember, iso-alpha-acids are the compound created when alpha acids are boiled during a brew).
Your King’s Blockhouse clocks in at about 56 IBU.
The human palate maxes out at around 80-100 IBU, but that doesn’t stop breweries from making beers with ridiculously high numbers – sometimes into the thousands.
We’ll keep ours at a reasonable level, as a balanced beer is often the best beer!