Some Thoughts on Bouckaert's Thoughts

Bouckaert brings up some interesting points in his keynote address of the NHC. In particular, he talks a bit about the large gap between what IBUs seem to tell us about a beer, and what sort of flavor impact they actually end up having. Starting at around the 27 minute mark, Bouckaert begins to tell an allegory wherein he has painted his house blue. Some others on the block decide to paint their houses blue as well, and eventually the homeowners association steps in to formalize a system to determine "blueness" after people begin bickering over whose house is more blue than whose. The system is put into place and each house now has a rating expressed in Blue Units, or BUs. (He then cracks an even better joke when he comments, "Since we are in the US, we actually call it International Bitterness Units.") He continues his story by telling of the fictional day that the homeowners association decided that their block should contain no houses with fewer than 40 IBUs. Even if his family doesn't like it, they are now left without the freedom to choose a new color.

It's not hard to see where he's going with this. (By the way, if you don't already know Bouckaert's position on styles, you should probably first look here. He rails against them.) He even comments on the inclusion of IBU ranges in style guidelines as "ridiculous." (Listen in at the 35:58 mark.) Why?

Because, as he aptly states, "This is a measurement, a measurement that is not relating to taste. I can make you a 40 IBU beer tasting like 25."

And he's right. There are a great many factors that play into creating the overall taste profile of any given beer. Original gravity, water mineral composition, particular hop choice, hopping schedule, fermentability of the wort, etc. all make significant contributions to how the beer will be perceived in the end. Is the bitterness perceived in a 40 IBU Czech Pilsner comparable to that perceived in a 40 IBU English Barleywine? Of course not.

We can still account for some of the differences here with numbers. The GU:BU ratio that Daniels uses in Designing Great Beers comes to mind. (For a beer of an OG of 1.050 and 50 IBUs, the GU:BU ratio would be 1:1.) However, this still isn't the whole story.

Let's talk about hopping schedules for a moment. Say that I want to make an Imperial IPA hopped exclusively with Centennial. Guidelines state that IBUs for this style can range from 60-100+. Using the Tinseth utilization that I so adore, I decided to run some numbers on potential IBUs of an Imperial IPA with an OG of 1.080. For comparison, here are the results of my two different hopping schedules.

Schedule #1:

2.5 ozs. Centennial (10% AA) @ 60 mins - IBU Contribution = 66 IBUs
1 oz. Centennial (10%AA) @ 15 mins - IBU Contribution = 13 IBUs
1 oz. Centennial (10% AA) @ 5 mins - IBU Contribution = 5 IBUS
.5 oz. Centennial (10% AA) @ 1 min - IBU Contribution = .5 IBUS

Total IBU Contributions = 84.5 IBUs

Schedule #2:

2.5 ozs. Centennial (10% AA) @ 20 mins - IBU Contribution = 40 IBUs
1.5 ozs. Centennial (10% AA) @ 15 mins - IBU Contribution = 20 IBUs
1.5 ozs. Centennial (10% AA) @ 10 mins - IBU Contribution = 14 IBUs
1.5 ozs. Centennial (10% AA) @ 5 mins - IBU Contributions = 8 IBUs
1 oz. Centennial (10% AA) @ 1 min - IBU Contribution = 1 IBU

Total IBU Contributions = 83 IBUs

As far as IBU totals go, these two beers are really close. However, the these beers would undoubtedly taste radically different. Where Schedule 1 would produce a beer with a substantial bitterness, Schedule 2 would not. Instead, Schedule 2 would be an over-the-top hop flavor/aroma apocalypse without the extreme bitterness at the end. Should we adopt a ratio of bittering hops to flavor/aroma hops in order to explain this? I'm not sure. But does that mean that inclusion of IBU ranges in the guidelines are "ridiculous"? Perhaps not.

I will say, even as a BJCP judge, that I do not think the guidelines are meant in this way. They are a tool. They can be helpful when designing a recipe for the first time, especially when brewing a style that one has not had the opportunity to try before. I recently brewed a British Mild. As these beers are primarily cask-conditioned real ales served on draught in England, I've never had one. To my knowledge, I've never had an American version of one either. But seeing that they tend to fall in the 10-25 IBU range is helpful - especially since I know that it is not a style where late hopping additions are commonplace. So when I'm doing my calculations, I can take that into account. Later on if I want to brew a Mild dry-hopped with Amarillo, no one's stopping me! However, to get the idea of how they've historically tasted, it behooves me to use the guidelines.

In the end, I appreciate where Bouckaert's coming from. If beer drinkers aren't willing to discuss the possible merits of a given beer becuse it doesn't fall into an established category, then we have a problem. Also, no amount of number crunching will improve how the beer comes together in the glass - that's a product of, as Bouckaert puts it, the knowledge, experience, and creativity of the brewer. That being said, I also think that guidelines can be very useful, especially for those who are new to beer. They succinctly explain many different types of beer and enable the brewer to recreate them, even if the brewer has little experience with the style.