What are IBU’s in beer.

I always seem to come across new and unknown terminology in the beer world. Its exciting when you can use that lingo when trying to comb through your drink choices at your local pub or during that brewery visit you had been putting off for so long. I also find it extremely helpful when choosing beer at the supermarket. For example, knowing what IBU’s are and what that means in relation to what type of beer you might be looking for is great and very helpful. Sometimes there is a nice little description on the six-pack or bottle of beer but it isn’t always that useful in helping you to decide based on flavor or even knowing what it actually might taste like.

IBU refers to International Bitterness Unit scale which is standard for measuring the amount of hops  in your beer. (Or the concentration of bitter hop acids in any given beer) That’s right folks, and its super helpful for hop heads, white beer and pale ale drinkers alike. IBU measurement is helpful for not only those of us who seek out that super bitter, hoppy flavor but also for those of you who hate hoppy beer. Just simply check out the IBU’s on your beer bottle and you’ll know if your going to regret buying a 24 pack of said beer or not. Often a very hoppy beer will have an IBU of perhaps 75 or 80 which is high, for obvious reasons and a more malty beer or even a light beer might have an IBU of somewhere around 30.

                                                                Let’s get down to the science of it!

More specifically IBU’s in a beer refer to the amount of Isohumolone, the acid that occurs in hops that actually gives your beer its bite.

Isohumolones, the chemical compounds that contribute to the bitterness level are themselves in another class of compounds known as isoalpha acids.

                                                          How it works chemically….If your interested. :-)

For all you darlings out there who absolutely loved second period of high school because you had chemistry class, then you might appreciate this seemingly useless information. Although, knowledge is power so who knows when you will need to know how the hops are broken down chemically in beer, right?

One IBU corresponds to one part-per-million of isohumolone. When beer is exposed to the light, the compounds decompose in a reaction catalyzed by riboflavin to then make a free radical species by the hemolytic cleavage of the exocyclic carbon-carbon bond. Whewww, what a mouthful!. The cleaved acyl-side chain radical then decomposes some more and then expels or releases carbon monoxide and creating 1,1 dimenthylallyl radical. This radical will finally react with sulfur containing amino acids, like cysteine to create 3-methyl but-2-ene-1-thiol. A thiol which causes your beer to taste “skunky” or “hoppy” or “bitter” or whatever you’d like to call it. Voila! That’s it!

What it looks like…..

isohumulone (hop acids in beer)

So that’s it, I hope this was more informative and interesting than boring, also there is a little list of other relevent beer and brewing terms. 🙂 ❤ Cassandra





Other Beer and brewing terminology

Aerobic– An organism, such as top-fermenting ale yeast, that needs oxygen to metabolize.

ABV– Alcohol By Volume- Amount of alcohol in beer in terms of percentage volume of alcohol per volume of beer.

Ale– Beers distinguished by use of top-fermenting yeast strains, often fruitiness is part of the character of ales.

Anaerobic– An organism such as bottom-fermented lager yeast, that is able to metabolize without oxygen present.

Barrel– A unit of measurement used by brewers in some countries. In Britain a Barrel holds 36 imperial gallons ( 1 imperial gallon= 4.5 US liters) ( or 1.63 hectoliters). A US  barrel holds 31.5 US gallons ( 1 US gallon = 3.8 liters) or 1.7 hectoliters.

Black malt– Partially malted barley, roasted at high temperatures. Black malt gives a dark color and roasted flavor to beer.


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