IBUs - Let's get this sorted out.

Discussion in 'Beer Talk' started by Hop-Droppen-Roll, Jul 1, 2014.

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  1. Hop-Droppen-Roll

    Hop-Droppen-Roll Initiate (0) Nov 5, 2013 Minnesota

    Every time the topic of IBUs comes up, someone mentions that it is a measure of bitterness. Someone immediately corrects this person and clarifies that IBUs measure something that correlates to bitterness but not bitterness itself. It never becomes totally clear what IBUs really measure - and what that means to the imbiber.

    Will someone please clarify exactly what it is that IBUs measure, and explain what the consumer can ascertain from the listed amount of IBUs on a beers label? I once had it pretty well explained to me by a beer geek at a restaurant before I really became an advocate, but I can't recall exactly how it all went, and I'd like to see a clear explanation in these forums at long last so that others who are unclear on this can find an answer.
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  2. markdrinksbeer

    markdrinksbeer Initiate (0) Nov 14, 2013 Massachusetts

    I will post something until someone far more educted happens along.
    IBU's measures the calculated alpha acids from the hops...which generally correlate with bitterness. More alpha acids, more bitterness. But, it also depends on the beer style. A stout can have 90 ibu's, but not be bitter at all, because the malt overpowers it. An ipa with 90 ibu's will be more bitter
  3. utopiajane

    utopiajane Poo-Bah (2,556) Jun 11, 2013 New York

    IBU's measure the measurable bitterness. That does'nt mean the same thing t everyone You might think that a bitterness off 75 is egregious, I might think 100 is acceptable. Try thebeer. BUY a single. I think that ultimately the idea that bitterness is masked by other flavors is true so try the beer.
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  4. Hop-Droppen-Roll


    I always get a little confused with the topic of bitterness - they say bitter is one of the 4 tastes, and sweet is another, but I always find that IPAs are very sweet tasting, and the bitterness is simply a distinct non-taste sensation on the back of my tounge. Am I crazy?
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  5. EcurbTheProphet

    EcurbTheProphet Initiate (70) Jun 12, 2014 Washington



    So... what Jane said... you can only get a general idea of the bitterness by this number alone.

    (I wanted to know myself... so I looked it up. This is an excerpt from this article; http://drinks.seriouseats.com/2013/...d-mean-dry-hopped-imperial-what-are-ibus.html)
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  6. StLeasy

    StLeasy Initiate (0) Sep 8, 2013 Illinois

    I'd guess that your body has just expanded its lupulin threshold :wink: Like you, I can feel the tongue-clenching bitterness, but it is a sensation I look forward to and enjoy in pales. The main flavors I taste are dank, citrusy, floral candy-like flavors.

    Like others, I wouldn't necessarily say "higher IBU= slower sipper", and probably closer to the opposite with many. I find that the higher IBU stouts and American barleywines are generally more quaffable to me, the bitterness seems to just add more-ishness.

    Not sure if anyone else has said it either, but IBU is a measure of how much lupulin (bitterness compound in hops) the beer has absorbed. Another thing I feel worth mentioning is that while many beers are listed "90 IBU" based on the recipe, the actual IBU is almost always a little lower if they test it with fancy machines. I recall an anecdote by someone from a brewing lecture that Sierra Nevada's Hoptimum has been the only beer to actually test at 100 IBU. Cheers
    #6 StLeasy, Jul 1, 2014
    Last edited: Jul 1, 2014
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  7. Roguer

    Roguer Poo-Bah (4,360) Mar 25, 2013 Georgia
    Moderator Society Trader

    I like what @EcurbTheProphet stated. Additionally:

    Instead of a measure of "bitterness," I see it as a measure of hop bitterness. As far as I know (very little, admittedly), big roasted malt bitterness doesn't figure into IBUs; high-IBU stouts are generally such because of the level of hopping, not because of a bitter roast (which absolutely is a factor in the flavor you detect).

    Further, dry-hopping theoretically adds flavor and aromatics without adding bitterness. Thus, if the alpha acids aren't being released, you might be able to add significant hop flavor without making it more bitter - and thus without raising the IBU rating.

    Further still, taste is of course rather subjective. Much like measuring refresh rates vs human reaction time (yeah, I'm a gamer), there is a limit to normal human perception. More IBUs might make something more technically bitter, but it may have passed your personal threshold as to what you can detect. 100 IBUs? Bitter-tasting. 1 million IBUs? Basically the same.

    Finally, yes, sweet and bitter are different taste profiles. A beer can be both. Remember the basic function of hops is to balance out the massive sweetness of the malts (similar to how phosphoric acid is added to soda to balance out the sweetness of the massive amount of sugar added). (Yes, there's more to this on both fronts. This is very, very basic.)

    So a big malt profile beer, that also has a lot of hops, can certainly be both bitter and sweet - just as it can be salty or sour.

    To me, the far more important question is not "How bitter is this?" but rather, "What makes this so bitter?" I haven't found a hoppy beer that's too bitter for me. I have found many lower-IBU beers that I perceive as too bitter, or at the very least, too bitter in an unenjoyable fashion. It's not about a number; it's about the overall presentation (for me and my palate).

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  8. Roguer

    Roguer Poo-Bah (4,360) Mar 25, 2013 Georgia
    Moderator Society Trader

  9. Leiermann

    Leiermann Aspirant (213) Jun 23, 2014 Pennsylvania

    If IBUs aren't a good indication of bitterness then someone should come up with a new method of measuring bitterness that gives the drinker a good idea of what to expect.
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  10. drtth

    drtth Poo-Bah (4,006) Nov 25, 2007 Pennsylvania

    Can't be done in any practical way. Too many variables influence perceived bitterness, including the distribution, number and type of tastebuds you have. And that is gradually changing such that about 7 years from now you'll have a whole different set than you have now.
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  11. Roguer

    Roguer Poo-Bah (4,360) Mar 25, 2013 Georgia
    Moderator Society Trader

    Not to be argumentative at all, but I honestly don't see why IBUs are a more important measurement than, say, sweetness. Some Belgian quads and dubs are rather sweet; others, dry and spicy, with very little sweetness.

    I'm OK with going by style and personal taste, and if I'm a little surprised, so be it. It's part of the fun. Honestly, there are far too many factors in a beer - including different factors directly impacting taste! - that aren't measured or reported at all, that I'm not going to worry if IBUs are imperfect.
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  12. MisSigsFan

    MisSigsFan Initiate (0) Mar 2, 2013 California

    Yes, that's correct. The bitterness from malts or additives like coffee don't figure into the calculated IBU, only AA from the hops.
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  13. drtth

    drtth Poo-Bah (4,006) Nov 25, 2007 Pennsylvania

    Right. Two different sources of bitterness. IBU measures only Alpha acids, as markdrinksbeer points out.
  14. whiskey

    whiskey Disciple (316) Feb 25, 2012 California

    I've never considered IBU's one time when deciding to drink a beer or not. Nor I have ever wondered how many IBU's a beer is or asked the question of anyone. I simply don't give a shit. It seems to try to put an exact number on a subjective thing. It's just weird to me.
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  15. Leiermann

    Leiermann Aspirant (213) Jun 23, 2014 Pennsylvania

    Still perhaps there is a way to measure excluding these factors. For example acidity is measured on a scale, can be given a number, and is related to bitterness. I guess perception is really a big factor, but you have to figure that most humans perceive tastes in the same basic ways, except for you super tasters out there...
  16. robear

    robear Initiate (0) May 24, 2014 Wisconsin

    It's all relative to the recipe. A beer drinker who understands gravity, SRM (color), and IBU's can reasonably estimate how the beer is going to taste based on those three measurements. A brewer can plug a recipe into a computer and calculate those same measurements before a beer is even brewed. Gravity (especially the ratio of OG:FG) will tell you abv, or how much sugar has been converted to alcohol and how much remains in the beer. SRM will tell you the types of malts used to get that sugar (and also give a sense of how the different malts will taste). IBU's will give you some sense of the hop bill. But IBU's are useless without knowing the gravity and SRM.

    So, if you have a low OG/low SRM beer with 15 IBU's, it still might taste pretty bitter.
    If you have a high OG/high SRM beer with 15 IBU's, you probably won't perceive any bitterness at all.

    That's a pretty extreme example. I like to use Black Husky Pale Ale as an example (and not only because it's my favorite Wisconsin beer). It's a pale ale, with an ABV of 7.2% (this is a simpler way of telling us that this beer has a medium-high OG/FG ratio), SRM of 6 (golden but not yellow) and 43 IBU's. At first glance, if I told you this was practically an IPA, you'd say, "43 IBU's? That doesn't seem like enough." But, for a Pale Ale to get to 7.2%, you know that the yeast has to have eaten through a ton of the sugars in the beer. That means that the beer isn't nearly as sweet as it would be if it were only allowed to get to 6%. Eating up that extra sugar allows the 43 IBU's to shine through the remaining sugar in this beer. It's still slightly sweet, but any less so and the simcoe hops would get over-powering.
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  17. LambicPentameter

    LambicPentameter Meyvn (1,486) Aug 29, 2012 Nebraska

    There is no reasonable way to measure actual perceived bitterness any more than there is a way to measure the other four flavors (there are actually said to be five flavors @Hop-Droppen-Roll : bitter, sour, salty, sweet, and umami, which is generally regarded as "savory"). The best you can do is measure something that can be objectively quantified--i.e., something that purportedly creates the flavor. Alpha acids for bitterness (which as noted, ignores the bitterness that can come from roasted/charred malts), sugar for sweetness, etc.

    The reason being that when the five flavors interplay, they impact how the others are perceived. Sweetness can take the bit off of sourness, and saltiness can enhance the presence of other flavors. It's too delicate an interplay to reasonably measure, so for me, IBUs are mostly a worthless measure. They'd do better to call it something like AAUs (alpha acid units) or some other kind of name that directly correlates to what it actually measures.
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  18. drtth

    drtth Poo-Bah (4,006) Nov 25, 2007 Pennsylvania

    Amount of Alpha Acid is not subjective and it can be given an exact value. Perceived bitterness, which is personal, can be quantified as well but it's too much work to be worth most people's time.
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  19. nc41

    nc41 Poo-Bah (1,945) Sep 25, 2008 North Carolina

    Big difference in calculated bitterness and perceived bitterness, and the difference is the malt. Session IPA's IMO and to my palate are horribly unbalanced and offensively bitter in the most extreme cases. Not a clue what the IBU's are, but it's essentially hop juice. DIPA's don't pack the bitter zing most IPA's do because of the malt which softens the bitter and ups the ABV. I'm not a scientific beer guy I'm sure an experienced brewer or home brewer could give you a more sound answer. I've had 100 IBU brews that were nicely hoppy and some 75 IBU brews which tasted far more bitter, I think the hop styles account towards perceptions.
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  20. beertunes

    beertunes Poo-Bah (6,344) Sep 24, 2007 Kyrgyzstan

    The type of hop needs to be taken into account as well. You could use some "softer" hops and end up with a beer that has XX IBUs. Using the same malt and yeast, but different, more "strong" hops, your IBU number may be lower, but perceived bitterness will be greater. All in all, I find the IBU number to be mostly unimportant. YMMV.
  21. hopfenunmaltz

    hopfenunmaltz Meyvn (1,467) Jun 8, 2005 Michigan

    It is the Isomorized Alpha Acid in beer that corresponds to IBUs, not the AA. Just to be correct.
  22. chefkevlar

    chefkevlar Aspirant (281) Apr 17, 2010 South Carolina

    First, acidity and bitterness are really two fundamentally different things as far as taste is concerned. They are two of the five things your tongue can actually detect (with the others being sweet, salty, and savory/umami). Second, it's possible to measure the pH of something just like you can measure the IBUs, residual sugar, salt content, or glutamate concentration. Those numbers would all from compounds that exist in precise concentration in whatever you are measuring, but to try to quantify the perception of those compounds in a way that would be accurate for everyone (or even a majority of people) would be impossible.
  23. geocool

    geocool Disciple (340) Jun 21, 2006 Massachusetts

  24. hopfenunmaltz

    hopfenunmaltz Meyvn (1,467) Jun 8, 2005 Michigan

    That is one tool. Considering the IBId and Final gravity is often usefull. Two beers with the same IBUs and same OG would cave different perceptions if the FG were different.
  25. rather

    rather Aspirant (202) May 31, 2013 California

    it's called a tongue :stuck_out_tongue: preferably your own.
  26. hopfenunmaltz

    hopfenunmaltz Meyvn (1,467) Jun 8, 2005 Michigan

    High Sulfate levels also give an enhanced sharp and lingering dry finish.
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  27. Greywulfken

    Greywulfken Poo-Bah (4,701) Aug 25, 2010 New York
    Society Trader

    Molecules in the hops, called alpha acids, change shape when heated (in a solution), becoming isomerized alpha acids. They cause the bitterness. 1 mg of iso-alpha acid in 1 liter of beer = 1 IBU.

    The more IBUs a beer has, the more bitter it is; BUT your ability to taste that bitterness is affected by the sugars in the beer. A higher IBU beer may even taste less bitter than a lower IBU beer, depending on the malt sugars.
  28. jmw

    jmw Initiate (0) Feb 4, 2009 North Carolina

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  29. superspak

    superspak Poo-Bah (32,418) May 5, 2010 Michigan
    Moderator Society Trader

    Cohumulone content in the hops being used has a big impact too, regardless of IBUs. Higher Cohumulone hops will be harsher on bitterness than ones with a lower amount of Cohumulone. Reasons I love Magnum and Warrior in home brews for clean bitterness...
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  30. hopfenunmaltz

    hopfenunmaltz Meyvn (1,467) Jun 8, 2005 Michigan

    To expand on jmw's post, we all have unique perceptions based on our genetics and experiences.

    Genetics explains why 20%of the population think that cilantro tastes like soap? PTC is a compound that is very bitter most, but 20% do not get any bitterness. Learn some science about taste and genetics here!

    There seems to be this misconception that acids are bitter, which is false. Acids give you sour flavors, acetic acids, lactic acid, citric acid, and so on are sour. Alkaloids are often bitter. Isomorized Alpha Acids are bitter. Here is a search result to lay that out.
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  31. rlcoffey

    rlcoffey Initiate (0) Apr 20, 2004 Kentucky

    Actually, its putting a number on a very objective thing -- the amount of isomerized alpha acids. Its as objective as abv.

    Just like with ibus, two beers with the same abv may have a different alcohol taste.
  32. drtth

    drtth Poo-Bah (4,006) Nov 25, 2007 Pennsylvania

    Prove it.
  33. drtth

    drtth Poo-Bah (4,006) Nov 25, 2007 Pennsylvania

    Genetics explains why some have blue eyes and some don't, but there are a small number of eye colors. Hair colors can be grouped into categories. Individual differences do not mean there are no commonalities and reasonable groupings.
  34. hopfenunmaltz

    hopfenunmaltz Meyvn (1,467) Jun 8, 2005 Michigan

    Read my post above. We are all genetically wired different for taste and aroma. We all have different blind spots. We all have different experiences that make up our taste memory.

    Breweries have tasting panels made up of personnel that have mutually exclusive blind spots. You don't want everyone one the panel that decides to package and ship a batch to be blind to Diacetyl.
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  35. hopfenunmaltz

    hopfenunmaltz Meyvn (1,467) Jun 8, 2005 Michigan

    It also explains why some are colorblind, or cannot taste certain compounds like PTC. Please read the link I posted on PTC.
  36. drtth

    drtth Poo-Bah (4,006) Nov 25, 2007 Pennsylvania

    I have, long ago.

    It clearly states there are groupings, eg PTC is tasted by about 75% of a given population, and that there is variability within populations and groups within populations. But that does not mean that every individual so unique that there are not commonalities or similarities within groupings.
  37. drtth

    drtth Poo-Bah (4,006) Nov 25, 2007 Pennsylvania

    I read your post above. If we all had different blind spots there would be no way to assemble a tasting panel without using all of us.

    Edit: there are a limited number of blind spots and reasonable groupings of people.
  38. hopfenunmaltz

    hopfenunmaltz Meyvn (1,467) Jun 8, 2005 Michigan

    OK, I see that your point about commonality groupings in genetics is valid. There are people I know who are hypersensitive to diacetyl and blind to DMS. Another gets both at low levels. Experience is also a big factor. Then there is the connection from the reptile brain to the verbal center, I go, know that taste, my wife will say what it is and I say yes. Her verbal connections are much stronger.
  39. hopfenunmaltz

    hopfenunmaltz Meyvn (1,467) Jun 8, 2005 Michigan

    Also a good point.

    Edit - so that is why we have beer advocate!!!
  40. drtth

    drtth Poo-Bah (4,006) Nov 25, 2007 Pennsylvania

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