Human IBU Sensitivity Threshold?

[Pelikan]

I've began wondering, just how apt is the human palate where bitterness is concerned? In other words, all things being equal (recipe, variety of hops, etc), where can one begin to detect a difference in bitterness levels? 10 IBU? 5 IBU? Even 1 IBU?

The issue is complicated by the fact that different people have different tastes, and the relationship between bitterness and sensation probably isn't linear. For example, it's most likely easier to tell the difference between 10 and 20 IBU, when compared to 60 or 70 IBU.

But I digress...

 

[Laughing_Gnome_Invisible]

I agree with your non linear theory. I voted +/- 5, but then I have been brewing low hopped beers in the 20/30 range. I'm sure I'd have much greater difficulty in a higher range.

 

[Jumbo82]

I think the threshold is probably more like +/- 20%. So you might be able to detect a change from 20 to 30 IBUs, but it would be much harder to detect from 80 to 90 IBUs. This is just wild speculation on my part, but it would be a fun experiment to try! Same grain bill, but ramping up the IBUs between test batches. Then a blind taste test. If you send me a bunch of bottles, I'd be more than willing to participate!

 

[Yooper]

I check 10 IBUs, but I agree that it's not linear. I can easily tell the difference between 15 IBUs and 25 IBUs, but between 85 and 95? Probably not so much.

One of the first things I did when I started brewing was make the Dead Guy clone. Then, about 3 months later, I did it as a full boil. To my unsoftwared mind, it was about twice as bitter. Not bad, though- just much more bitter. I later got software and ran the recipe. Sure enough- original recipe was 15 IBUs, full boil was near 30 IBUs.

I also think that if the beer is "bigger", it needs more bittering to balance it out. So sometimes a 30 IBU beer is too bitter, while a 80 IBU beer is not. It's the whole recipe that needs to be considered when bittering.

 

[Revvy]

You might find this discussion on BasicBrewing interesting.

March 20, 2008 - What Is an IBU . . . Really?
John Palmer, author of How to Brew, shares information from a conference that challenged his concept of what defines an International Bitterness Unit (IBU).

Click to listen.
http://media.libsyn.com/media/basicbrewing/bbr03-20-08ibu.mp3

 

[david_42]

I took an off-flavor seminar with about 20 BJCP types. One exercise was 10-20-30-40 IBU, line them up. Only one person got the order correct.

 

[Laughing_Gnome_Invisible]

I took an off-flavor seminar with about 20 BJCP types. One exercise was 10-20-30-40 IBU, line them up. Only one person got the order correct.

It would be interesting to know if the mistakes were speread evenly or, as I suspect, more at the higher end.

 

[OutThere]

I work for a brewery and our specifications for bitterness are based on 10% and 15% limits. So a beer that varies from the spec by 10% will be noticeable upon side by side comparison with beer that is within specifications, but generally not noticeable enough to require a fix. At 15% out of spec it is noticeable to "the average consumer" and needs a fix/blend. In my experience these rules are pretty true to reality.

As far as minimum detectable bitterness in beer goes, it is somewhere between 4 and 7 IBU depending on what source you consult. Interestingly enough, some of the mainstream American Lagers fall right around the 7-9 IBU range when they are tested; they barely taste better than water. Enjoy!

 

[avaserfi]

Bitterness/sweetness ratio will also play a large part in perceived bitterness. So, beers that are more malty will taste mask bitterness and vice versa. Just another factor to think about. I think if one is trying to chart perception of bitterness the malt factor will have to be accounted for in some way.

 

[david_42]

It would be interesting to know if the mistakes were speread evenly or, as I suspect, more at the higher end.

My impress was most people either got 20/30 reversed or 30/40.

 

[TexLaw]

If it the recipe were fairly light on the malt (i.e., say around 1.035-40), I can easily see a drinker mixing up the 30 and 40 IBU samples. Both would be quite bitter and difficult for most folks to distinguish. That's especially true for folks accustomed to BMC.

The 10 IBU sample probably would be quite sweet, and the 20 IBU one probably would be about right for my tastes.


TL

 

[mkling]

I think the threshold is probably more like +/- 20%. So you might be able to detect a change from 20 to 30 IBUs, but it would be much harder to detect from 80 to 90 IBUs. This is just wild speculation on my part, but it would be a fun experiment to try! Same grain bill, but ramping up the IBUs between test batches. Then a blind taste test. If you send me a bunch of bottles, I'd be more than willing to participate!

Jumbo82 got it almost exactly right, and this corresponds to Weber's Law of perception, one of the first psychological laws dating back to the late 1800's. Weber's Law states that the size of the just noticeable difference (the minimal detectable difference between two sensations) is a constant proportion of the original stimulus value. This has been documented with many kinds of sensation -- weight placed in one's hand, brightness of a light, size of objects, loudness of sounds, etc. What varies is what that crucial proportion is.

Doing Jumbo's experiment above would be very worthwhile & is exactly the way to figure this out.

 

[Christian]

I have an IIPA that i brewed that i estimate to be around 80+ and this last weekend i compared it to a Stone Ruination that is 100+ and i could barely tell the difference if at all.

 

[bb239605]

I believe that anything past 60 IBUs is untectable by humans. I remember reading something like that in one of my brew books

 

[wildwest450]

I believe that anything past 60 IBUs is untectable by humans. I remember reading something like that in one of my brew books

You need a new brewing book.


_

 

[Stratotankard]

I brewed an IIPA this weekend with a theoretical 296 IBU. I was bitter, but no more bitter than the Stone IIPA I had over New Years. I know all the debate over maximum extract and that seems to support it for me.

As far as perceived bitterness, I'm saying non-linear and starting around 5 IBU change at the low end before it's noticeable.

 

[PHBalanced]

I brewed an IIPA this weekend with a theoretical 296 IBU.

WOW! That just seems crazy. Got a recipe to share?

 

[rjwhite41]

I brewed an IIPA this weekend with a theoretical 296 IBU. I was bitter, but no more bitter than the Stone IIPA I had over New Years.

While not as crazy as that my IIPA's generally clock in around 160-180 and I wouldn't call them exceptionally bitter.

 

[Stratotankard]

I posted the recipe on this thread. The brew didn't go so well, but I'm thinking I can salvage a decent beer out of it.

Terje