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| The IBU Contributor - Hops Shown Dried and in Whole-Leaf Form |
Beer has many values quantified by a numbered scale of some kind. The common ones are: color, ABV, and bitterness. Because bitterness is an important characteristic in most beer styles, it is only natural it has its own term. This value is identified by International Bittering Units, or simply IBU. This term, IBU, is often used in pub conversation and are usually found on the description on the beer on a beer board or packaging. If you are unfamiliar with what an IBU is, continue-on and I will demystify things.
IBU values are good indicators on how bitter a particular beer will be. The short answer is the simplest way of explaining this: On average, the higher the IBU’s a beer has, the higher the perceived bitterness will be on your palate (and vice-versa, the lower the IBU’s, the less bitterness perceived). This is a good rule-of-thumb to go by.
Here are a couple of examples to further explain that concept: a Belgian Wit might have IBU’s of around 12 while an American Pale will proudly boast 40 IBU’s. A German Dunkel could have IBU’s around 20 while an Imperial/Double India Pale Ale could tip the scales at 100+ IBU’s! (FYI, Budweiser has about 5 IBU’s)
What causes bitteness in beer? ...Hops! Without crumbling open a hop cone to study the anatomy, there are two basic components you need to be aware of: the Essential Oils and Alpha Acids (AA). Essential Oils contribute aroma and flavor characteristics and we will tackle that at a later time. The Alpha Acids are what add bitterness. The AA’s are quantified by percentage with the higher percentage meaning higher bittering properties. For instance, the German hop Hallertau will have about 4%AA with a pleasant bittering contribution while the American verity Simcoe will average at around 13%AA.
I won’t bore you with the math behind this, but the concept is straightforward. The AA’s must be boiled in the wort (pre-beer) to add the bitterness properties. Depending on how long the hops are boiled in the kettle, the sugar content of the wort, and the amount of hops used will determine the total IBU’s in the finished beer.
One internal factor contributes to the bitterness (or lake thereof) we actually perceive. Although we can use the IBU’s provided gives us as a good base-point, the beer ingredients can hinder the actual amount of bitterness that comes though. For example, heavily roasted malts will subdue some of the bitterness perceived. Another way bitterness can be subdued depends on how the beer is dispensed. A casked-conditioned or nitor beer will have significantly less bitterness than the same beer served with average volumes of CO2, regardless of having identical IBU’s.
Before I sign off, here are two interesting notes on IBU’s. Humans have a limit to the amount of bitterness we can perceive. It’s still an on-going debate in the scientific community, but the common numbers given out are usually around 80-100 IBU’s before we max out. Another item to ponder about is the limit of IBU’s that can physically be dissolved into a particular beer depending on the sugar content. I still need to research this item further, but it’s an interesting topic. Homebrewer might find this especially appealing.
Well, there you have it. If you did not know what an IBU was before and had a tough time following a conversation or reading a beer description, this should give you some solid ground to stand on. If you don’t like bitter, stay away from high IBU’s. If you do, then seek out the highest IBU beer you can. At the end of the day, it’s as simple as that.
Thanks for reading. I hope you enjoyed it and learned a thing or two.
Until next time!
Cheers,
-Gilbert “Charlie” Perez, Certified Cicerone®
-Gilbert “Charlie” Perez, Certified Cicerone®