IBU Theory

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xxHelderxx

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Hi Everyone,

I've done a search but can't find any threads dedicated to IBU theory. I know it can get a bit technical and dense but I'd like to learn some things regarding how many IBUs I can actually get into a beer (I've heard the max is ~100) and what any additional hops contribute to the flavor profile of a beer. I'm formulating a recipe and want to know at which point I'm just wasting money by adding hops. Here is a sample hops schedule for reference:

.5oz Columbus (FWH) @14.5%
1oz Columbus 60 min @14.5%
1oz Nuggest 60 min @ 12.2%
.5oz Columbus 45 min @ 14.5%
1 oz Nuggest 45 min @12.2%
1oz Centennial 30 min @9.7%
1oz Williamette 10 min @ 4.8%
.5oz Centennial 10 min @9.7%
1oz Williamette 13 days dry hop @4.8%
.5oz Centennial 13 days dry hop @9.7%

My BrewPal app tells me that should be 164 IBUs but I know there are several caveats to that.

Can anyone help me to understand what's actually going on here in terms of IBUs?

Also, I've read about additions longer than 20 mins contributing little to no flavor, so is there also room in this schedule for some movement in order to be more efficient?

Thanks!!
 
For really bitter beers I tend to aim for ~150 IBUs, even though the measured value rarely if ever goes over 100. You are probably pretty close to saturating the beer with bitterness, but you could add plenty more aromatics. I would shift the 30/45 min additions up to 60 and down to 0 to get the most out of them. I'd also double the dry hop if you want an agressive hop nose.
 
For bitterness, there are several formulas out there but Tinseth is generally considered to be best of breed. That said, it is several years old and a lot of the thinking has changed since then. The formula is described here. I think the general consensus is that you start getting sharply declining returns past 100 IBU, but I don't know of any real research on the matter.

As far as flavor goes, this idea of "early=bitterness, late=flavor/aroma" is sometimes overstated. It is certainly true that longer boil hops will contribute more bitterness and shorter boil hops will tend to be more aromatic, but it isn't really accurate to say that additions longer than 20 minutes add no flavor. For starters, bitter is a flavor, right? But even if you mean something more specific by "flavor" (i.e., variety-specific character), different types of bittering hops will lend different characteristics to the beer.

:mug:
 
Thanks OldSock and Malfet.

Having read what you both posted, I'm still a little curious about my hop schedule above. Is there any way for me to look at this and understand if I'm essentially using more than need be for the resulting IBUs?
 
I guess I'm not sure I understand your question. None of your hops is going to "waste" if that is what you mean. When trying to brew a beer of very high IBU, it ends up being a bit inefficient just because of the diminishing return factor. If you take any of those hops out, you'll end up with a different, less bitter profile. It is not as though you get full extraction of hops up to 100 IBU and then a complete stop past that, at least not according to my understanding of isomerization and diffusion.

If you want more bitterness from the same amount of hops, you can do what oldsock suggests and push some of your middle additions earlier. If you want more hop nose, you can push some of your late additions to whirlpool (or even add more then).
 
Thanks again Malfet- you answered my question which was more regarding hop timing to achieve more bitterness.

Samc thanks for that link! I'm really curious about this subject.

Thanks to all!
 
I wondered about a similar thing when I started thinking about formulating some IIPAs. I looked at a bunch of recipes and pretty much came to the conclusion that so long as you have about 2oz of high alpha hops (like 14% and up) at the beginning of your boil, you'll approach maximum bitterness. Couple that with some hefty late additions and you'll almost certainly hit it.

I've definitely found that I get more bitterness (or apparent bitterness if that's a thing) when I do some sort of continuous hopping. For a barleywine I intended to age a long time, I did one 60 min addition, and then a bunch of half oz additions every 5 minutes from 30 minutes onward.

So I'd say that anything more than 2-3oz for your bittering addition is waste. Extra hops should be used for late additions.
 
Thanks Kanzimonson- this is basically the anectodtal info I was looking for. I just wasn't sure if there were any hard and fast kind of formulations for understanding the IBU or as you said "perceived" bitterness drop off of hops that would bring you in excess of 100 IBU.

I think it will end up being more of a trial and error exercise.
 
The human palate supposedly can't detect any past 100 IBU, but those hops still add flavor and changing the additions will affect the profile of the beer--even if it stays above 100 IBU.
 
I think you might be mixing two factoids here. I've heard:

1) You can't dissolve more than 100IBUs in solution and
2) The human tongue can't perceive less than 10IBUs, or a 5IBU difference in two beers

Whether either of these is true is questionable to me, but I think these are the oft repeated phrases.
 
I think you might be mixing two factoids here. I've heard:

1) You can't dissolve more than 100IBUs in solution and
2) The human tongue can't perceive less than 10IBUs, or a 5IBU difference in two beers

Whether either of these is true is questionable to me, but I think these are the oft repeated phrases.

Good call separating these two things. I'd love to hear science-y explanations from the ScienceGuys, but I'm not sure I immediately believe #1 based on my (pathetic, probably incorrect) understanding of the mechanics involved. #2 is also an empirical question, but I am more inclined to buy it. Anecdotally, I've not been able to distinguish in terms of bitterness "normal" super-bitter beers (~100 IBUs) and super-super-bitter beers (>150 IBUs).

That said, hop additions do add more character than just bitterness, even the really early adds. It is tough to disambiguate all this stuff properly, but I imagine that one 100 IBU beer and another identical but +50 IBU from early additions would taste different. It sounds like a good experiment.
 
And all of this discussion isn't even including things like "low cohumulone hops have a smoother bitterness" (or whatever it is).

I'm not sure I believe that as a straight-out fact either. I think like yeast, hop chemistry is a field where we know a whole bunch, and yet there's so much more to learn. There's a lot of "it depends" because it seems like everything that we taste in beer has a multi-faceted explanation.

Here's something I've started to notice in my beers: when I have small bittering additions with big late additions, the bitterness has a more "physical" property to it. Like my tongue is coated with a thick resin. There's a sweetness to the resiny sensation as well. I noticed this in a brown ale I made with 14g of 8.1% bittering hops, and 56g of the same at both 10min and 0min.
 
My chem prof is a UC Davis graduated brewmaster and brewing consultant on the side and it's his word that anything past 100 IBU is undetectable to humans as far as bitterness goes. He claims that "super charged" beers like Green Flash Palate Wrecker give the perception of heavier bitterness with their 200+ IBU beers because of crazy early additions paired with hop bursting or in some cases reducing body, unfermentables, and FG. Dunno. Just being a parrot here.
 
Oh man, I had never heard of the Palate Wrecker but I sure love their Imperial IPA. Just read on the site how they make it - sounds kinda ridiculous and wasteful but a fun experiment.

As for 100 being the max perception, I guess I could imagine a situation where all points on your tongue are so saturated with isomerized acids that you can't taste anymore bitterness. Too bad a lot of this stuff is about subjective taste perception.
 
True true.

Yeah, Palate Wrecker is insane. You should seek it out if you ever find yourself in the area. It's a treat, but honestly not something I could drink regularly. I recently had Pliny the Younger and I think Palate Wrecker is more suited for hop heads. Comparing apples and oranges I know, but still.
 
I thought a lot about all these questions when I was getting ready to brew Liquid Novacaine. It has a theoretical 296 IBUs. Having brewed it, I can say that while it is very bitter, it isn't much (if any) more bitter than many other 120-160 IBU beers I've had. It does have more flavour and body, though, that may just be a perception.

So not a very scientific answer, but more of a anecdotal one. I say use the extra hops. There's no such thing as wasting them short of flushing them down the toilet.

Terje
 
This question most definitely has several moving parts. The 2nd one we're addressing here in terms of perceiving bitterness in excess of 100 IBUs seems heavily subjective to me. Also, as the previous poster noted, isnt it worth calling out the fact that the perceived bitterness is a function of how sweet/malty the beer is or is not?

I recently tried Lagunitas Hop Stoopid/Stone Ruination/Green Flash Imperial IPA and although they're all >100 IBUs supposedly, they had distinctly different bitterness levels.

While all of them were "holy crap" hoppy, I defintitely agree with other characteristics being lended to the beer besides straight bitterness. But the ligther (in color) beer of the lot (Stone Ruination) definitely had more of a souring/citrusy effect.

anyway- that was rambling. I'd love to do a single malt brew, like a 2 Row with the same hops @ the same AA% and just mess with the amount of IBU going in to the beer and seeing if there is any perceived bitterness difference at different thresholds.

I'll need to free up some ferm space!
 
Of the beers mentioned in this thread, I think that Stone Ruination is most distinct in the "type of bitterness" it has. Unlike the thick, resiny bitterness I mentioned above, I think Ruination has a very "classic" bitterness - it's obviously very high in IBU, but it's almost a light-tasting bitterness to me. It doesn't linger for several minutes like a lot of other IIPAs do.

Maybe we're all just blowing smoke, though.
 
Sorry to bring this topic back up, but I was just thinking about the so-called "100 IBU limit" and it's absurd to think that's really a max. What happens if you take a IIPA and boil it down until it's reduced by half? How much more bitter could you get a beer if you kept boiling it down? That also is a strong reminder to get the bulk of your bittering from early additions when you're making a max-IBU beer.
 
2) The human tongue can't perceive less than 10IBUs, or a 5IBU difference in two beers

I don't think this is accurate. I'm willing to bet that it is more of an exponential factor. The higher IBUs you have, the harder it is to distinguish the difference. When comparing 95 to 100 IBUs is very difficult to know the difference, but comparing 5 IBUs to 10 IBUs, it is very easy to distinguish the difference.

I see it as similar to comparing grains of sand. Comparing a pile of 5 grains and 10 grains, it is very easy to notice the difference, but if you compare a pile of 90 grains to 95 grains, it is much harder to determine which is which.
 
I'll buy that logic.

I've also heard Dan Gordon say that any brewer worth his salt should be able to drink a beer and tell you how many IBUs it has, within 3.
 
I think that what you are looking for in a formula to calculate real and perceived IBU's in very large amounts does not exist. There is still a lot that is not understood about hop utilization and isomerization. There are also so many factors involved like water chemistry and tasting ability.
 
The human palate supposedly can't detect any past 100 IBU, but those hops still add flavor and changing the additions will affect the profile of the beer--even if it stays above 100 IBU.

This is true. I just learned about this the other day. It makes perfect sense. We can only taste ~100 IBU of BITTERNESS. That is what IBU is. However you are completely right about adding hops to change taste. I mean if you added a higher AA hop to the flavoring schedule, it won't change the amount of bitterness we taste, but it will certainly change the taste.
 
Up until my last 2 batches, I've done parital boils. There are those that say that you max out at 100 IBU in the boil volume. So, if you dilute/bring to full volume after the boil, you dilute the IBUs from 100 downward depending on the amount of added wwater. This never made sense to me but I have had my beers coming out less than my intended bitterness. I researched quite a bit and never found a good explanation as to why the 100IBU/dilutin idea would be true.

However, my last 2 batches were full boil and the first should be ready next week. So I should be able to get a rough idea of whether or not the idea holds true for my system. I'll try to post when I get a chance if anyone is interested.
 
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