Thursday, August 30, 2012

IBUs In IPAs - Misconceptions About How Hops Work

Power Level 90 IBU's!? That's... impossible!

IPAs are the poster child of the craft beer revolution, the first style to really explode out of the gate and define our new, Golden Age of beer. Nowadays there are probably more distinct sub-genres of the IPA than there were individual IPAs being brewed forty years ago. We've got American IPAs, British IPAs, Belgian IPAs, imperial IPAs, rye IPAs, white IPAs, black IPAs, Brett IPAs, et cetera. Differentiate by hop character, and you could have dozens more styles: dank, piney, citrusy, grapefruity, tropical, spicy, herbal, and so on.

So, IPAs are a complex lot, and it's easy to understand how some confusion could arise. Many aspects of brewing are poorly understood, and the way IPAs are marketed is often misleading. IPAs introduced the public to a new unit of measurement on their beer bottles: the IBU, or International Bitterness Units. Because IPAs are known for being bitter, they gave us a new way to judge a beer by its cover, and as such, sparked a sort of IBU Arms Race between brewers for a few years. Unfortunately, IBUs are a bit more complicated than those innocent looking digits would indicate, and this numerical-bitterness-grandstanding provides an easy crux. It seems to mean more than it actually does, and allows you to compare one beer against another with an apparently straightforward, 'mathematical' Red Herring that in actuality is rendered meaningless the more it goes up, like Power Levels in DragonBall Z. And thus, you have both brewers and drinkers assuming that a hoppy beer will grow more potent on an exactly linear scale, cowering in slack-jawed astonishment that an IPA could possibly achieve such a high IBU Power Level, and thus threaten to blow up the moon, or whatever.

Take this Men's Journal write-up about their "25 best beers in the world." The author attempts to explain the superiority of Dogfish Head's 90 Minute IPA with this passage: "It should be impossible for a beer that's been hopped for 90 solid minutes (an average IPA gets 60) to be delicious; in fact, each sip should be like snorting aspirin."

Snorting aspirin? Whoa there, champ, maybe your unorthodox aspirin intake is the problem in the first place. 90 Minute is, in fact, a solid IPA, and there's nothing wrong with the marketing strategy Dogfish chose. It was one of the first imperial IPAs to catch the public eye, and they were going for something that would make it clear this was a big hoppy beer, so sure, why not emphasize your unique hopping technique in order to set it apart. But the name does play into the arm's race and misinformation surrounding bitterness in beer, making it seem as if there's something outlandish and insane about hopping a beer for 90 minutes straight. There could be, depending how the hops were used, and how many. I mean, say 90 Minute was hopped with half an ounce of hops every minute for 90 minutes. Would that be as hoppy as a beer that was hopped for only one minute... with a thousand pounds of hops?

What IBUs Mean
You probably already knew that "IBU" stands for International Bittering Unit. So, the higher the IBU figure, the more bitter the beer... in theory. But that doesn't tell the whole story, because all Bittering Units are not created equally.

Let's take two couples. First, we have two high school seniors in Kansas, sixteen years old or whatever is a normal age for high school seniors to be, going to their senior prom. The second couple are in their late 20's, live in New York City, and just met online.

Let's start with the older couple, the one in their late 20's. The lady asks the dude: "How many serious long-term girlfriends have you had?" His answer is ten. Back to the younger couple, the high school seniors at prom. The sixteen year old girl, also, asks her sixteen year old guy: "How many serious long-term girlfriends have you had?" His answer is also ten.

Both the exact same number, but one answer is a bit more jarring than the other, no?

It doesn't matter what your high score is. Well, no, that's not fair — it does matter. But it is also matters at what time you acquired that score. If you racked up those numbers early on, it's going to raise eyebrows a lot more than if you accumulated your score later. Dogfish Head's 90 Minute IPA tells you nothing about how many hops were used, it just indicates when the hops were added. As it turns out, both are just as important.

How Hops Impart Bitterness
Bitterness is derived from the resinous Alpha Acid content of hops, which is only soluble in boiling water. In other words: the longer hops spend in the boil, the more bitterness they impart. Conversely, the aromatic oils contained in hops are boiled off quickly, so that the more time they spend in boiling wort, the less flavor and aroma they will contribute. The standard duration of a boil is 60 (up to 90) minutes, and hops boiled for this amount of time will contribute all of their bitterness, but very little flavor, and no aroma. Different hops contain different percentages of Alpha Acids — meaning more potential bitterness the higher the percentage — and IBUs are approximated with a formula that factors in Alpha Acid percentage and amount of time boiled. (I say "approximated" because there is a big difference between calculated IBUs and perceived IBUs — but we'll get to that.)

Brewers generally classify the hops used during the brew two ways: bittering hops and flavor/aroma hops. Bittering hops are added at the beginning of the boil, are boiled the longest, for 60 to 90 minutes, and contribute mostly bitterness. Flavor and aroma hops are added toward the end of the boil, and contribute mostly flavor and aroma. Make sense?

So, keeping in mind my previous Number of Girlfriends/Age analogy, let's consider this scenario: Brewer A adds an amount of hops to his boiling wort at 60 minutes such that they add up to 60 IBUs. Brewer Z adds an amount of hops to his boiling wort at 10 minutes such that they add up to 60 IBUs. Are these two beers going to taste equally bitter? No, not at all. These two beers will taste very different. Beer A will taste bitter, but have little hop nuance or aroma. Beer Z may also have noticeable bitterness, but will have developed a much more pronounced, complex hop character due to the timing of the hop additions, and the perceived bitterness will be significantly lower even if the brewer actually had to use more hops to hit the same calculated IBUs. This revelation has resulted in a whole new technique called "hopbursting," in which almost all of the hops are added very late in the boil — generally within the last twenty minutes — creating a beer that tastes much less bitter than its IBUs might indicate, while boasting a richer, more aromatic hop character.

Anecdotally: I have brewed a number of IPAs and pale ales that have significantly higher IBUs than their style calls for. This is because I used a lot of aromatic, flavorful hops as late additions, and very little for bittering. Software calculations will indicate that my Nelson Sauvin pale ale is over 80 IBUs, yet the beer is only 4.3% ABV. Men's Journal would tell you that my pale ale would be as bitter as having a shotgun blast of aspirin cut with horseradish fired directly into your nose. It is not. At least a dozen people have tried it at this point, among them a number of people who "don't like IPAs," and not one person has complained to me that it was too bitter — in fact, no one has even mentioned the word "bitter" at all when describing it. I don't tell most people what the IBUs are, and no one has asked.

Humans Can Probably Only Taste Around 120 IBU, Anyway
Anyway, humans can probably only taste up to 120 IBUs. Hops are not like spicy peppers, where they just get more potent and potent to the point of insanity. There is no hop equivalent to a Ghost Pepper, at least not that's been created by hop breeders yet. (Although you guys might want to get on that; "Ghost" would be a pretty badass name for a hop variety.) As you may remember from just the last section, IBUs matter much less than how you used the hops that you used. Some varieties, also due to their chemical makeup, will taste much more 'harsh' than other varieties, even at the same measured IBUs. Of course, it's much easier to share a simple number than it is to explain the harshness of different varieties, and how they were used.

Bitterness Doesn't Scale at The Same Rate as Sweetness
You may be surprised to hear this, but I used to think I hated IPAs, way back in my days of youthful ignorance. I know, I know. Everyone comes around eventually. Oddly enough, imperial IPAs got me into the idea that bitterness in beer was approachable. Like many people, I was initially attracted to sweeter styles, and found that imperial IPAs were actually, surprisingly, sweet. Because they are, almost always, exceedingly sweet. To this day, it utterly confuses me when a brewery advertises how devastatingly, tongue-numbingly hoppy their imperial IPA is (85 IBUs!!!!!), yet the beer turns out to be a rich, caramely booze-fest.

Mostly, this is because bitterness does not scale at the same rate as malty sweetness. In other words, if you increase your malt and increase your hops directly proportional to one another, eventually your imperial ale will be much sweeter than it is bitter. As mentioned above, humans can only taste bitterness to a certain extent before it just flatlines on our tongue. Malty sweetness seems to increase on a more linear scale, and sugar also tends to mask bitterness. If you take the most evil, bitter, black espresso in the world, and dump fifteen packets of sugar in it, guess what? It's going to taste sweet; doesn't matter how dark you made it in the first place. This is why most imperial stouts and barleywines — beers that are designed to be fairly sweet, and high ABV — often hit or surpass 80 IBUs, even if they're not advertised as bitter beers. Or take Dogfish Head's 120 Minute IPA, which is advertised as an IPA — in fact, the next up from 90 Minute. Does it taste like sticking your head into a cage full of bees that are covered in aspirin? Nope. Actually, it's super sweet and rich, because it's like freaking 240% ABV. It's basically a hoppy super-barleywine, and it tastes like it. It's a truly unique and interesting beer, but the level of hoppiness is not the part that's going to knock you to the floor.

The other reason imperial IPAs are often too sweet? Hops fade rapidly; malty sweetness does not.

Hoppiness / Bitterness Fades Rapidly
IPAs, perhaps more than any other style of beer, need to be consumed fresh. There is a general attitude out there that beer is always best fresh, and always best on tap at your local bar. Largely, this is a misconception — many styles of beer will age and improve for years while sitting in your basement. But not IPAs. Much like references to goofy 90's anime series, hops do not hold up over time. IBUs will decrease by about half per year. Hop aroma and hop flavor decreases almost immediately. This is not to say that you shouldn't drink an IPA if it is two months old; most times an IPA will not taste "bad" even after a number of months. Unless, of course, it was stored improperly — I once had a bottle of Dogfish Head 60 Minute that tasted like barbequed shrimp. It's generally not a good idea to buy an IPA that has obviously been relegated to the dusty back shelf of some remote gas station for a year.

The fresher an IPA, the better it will be, and sadly, the best IPAs will lose their edge fastest of all. An IPA that was never very hoppy to begin with may remain largely unchanged for months, but something with an epic kickpunch of hop aroma like Heady Topper needs to be consumed within a couple weeks. This is partly why it is futile to debate the supremacy of an IPA brewed on the other side of the country, unless you go to that side of the country to drink it. I've been fortunate enough to try Pliny the Elder a few times now — always a month old, or more — and while it is obviously a very well crafted beer, nothing really set it apart from other great IPAs I've had. And I assume this would likely be different if I were drinking it fresh at the brewery.

So it is for this reason that you should especially support your local IPAs. Every state, every region, deserves a few great IPAs, so that locals there can enjoy something fresh with confidence. And please, brewers: give us some hint as to how fresh it is on the bottle.

Hopping a Beer for 90 Minutes
As you will hopefully realize, having now read this whole dissertation, hopping a beer continuously for 90 minutes is more of a statement than a hardcore brewing technique. With enough hops, or hops with a high enough Alpha Acid makeup, you can easily brew a 90 IBU beer by adding the hops at almost any time in the boil (except the very end.) In fact, conventional wisdom these days is not not use any hops between 60 minutes and ~20 minutes. Because, again: anything added before 20 minutes will mostly lose its flavor and aroma, and the amount of bitterness you'll get from a 30 minute addition could be achieved with even fewer hops added at 60 minutes. So is 90 Minute the most efficient use of hops? Probably not, but like I said, it's a statement, and there's nothing wrong with how Dogfish does it. It certainly creates a unique beer, and maybe brewing it a different way wouldn't taste quite the same. But it's certainly not the reason the beer is drinkable.

Beer is far more complex than most people realize, but complexity rarely translates into effective marketing. Regardless what the label says, regardless what the the tap list at your bar says, you can never pigeonhole a beer without trying it. Even if you don't usually like IPAs, there will doubtless be some out there you do enjoy — IPAs are a complex lot, covering a wide range of flavors. As always, keep an open mind, drink a lot of beer, and you'll find something you love. Just try not to snort too much aspirin first.


  1. Nice article. Really, who needs a beer that says it has 2500 IBUs on the label? What a waste of hops. I wrote something very similar on IPA day in the spirit of rebellion against the concept.

  2. I enjoy your analogies.

  3. Great article!

  4. Nice write up on IBUs. I just brewed a double IPA that calculated out to 224 IBUs. Probably the best i've ever made. Not overpowering as you might think. 1.5 oz. FWH. One ounce at 60 min. half ounce at 30 and the rest at 15 to 0 min. Oh yeah, and a bunch in the kettle for a 30 min. hop stand at 170 degrees. Probably could have done without the total amount tossed in during the last 15 min. but it was worth it.

  5. Awesome article. I basically scoured the internet hoping to find this as I hust brewed an IPA that was around 100 IBUs and only 5.5% which blows way out of style guides. Most of those IBUs were hop bursting the last 20 minutes so hopefully its all good.

    1. Glad you found it! With lots of hopbursting, I think you'll be good — like I mentioned in the article I've brewed a lot of beers like this. Enjoy the tasty beer!

  6. Humans do have a roof for hotness as well. Once every receptor has capsaicin bound to it you cannot really get any hotter.

  7. I have a question. Just started brewing last year. I am having troubles getting any of my beers to have much of an "IPA" hops taste to them. Most of the recipes Ive been making usually have been say .75 oz for 60 minutes, then a .5 oz at 15 minute mark, and say .5 oz at 5 minute mark. But my beers end up being very malty tasting. While this hops addition is just an example, They usually don't deviate from this TOO much. What can I do to add more hops taste to my beer? Would you add more hops near the end? or more at the beginning? Thank you.

    1. Give this a good read.

    2. Mineral content and PH control is important.


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