IBU's

The Homebrew Forum

Help Support The Homebrew Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
This is very interesting. A while ago I posted a recipe for an Amarillo smash that I had made that had turned out very nicely. Someone pointed our that it had a predicted IBU of about 120 (in either Brewfather or Brewsmith, I can't remember which) and so was far too heavily hopped. It was hop forward (as intended) but not unbalanced and was one of the more enjoyable beers I have made. The graph suggests that, being at the higher end of the IBU scale, the predicted value would have overestimated the IBU considerably, which is what my taste buds were telling me.
Exactly, I have posted many times on here that my clones could not replicate the IBU's which were quoted in the clone recipe. OSH was well below in bitterness to what I have tasted before. I was starting to believe that beers were not brewed to style, reading the article and seeing the work which has gone into it with the author and Oregon State University, I feel somehow vindicated for feeling that something was wrong, especially for my liking of a hop forward beer. Though as home brewers we cannot expect to ever get an accurate IBU reading we can confidently go forward using our taste buds to lead us instead of taking note of, 'Not to style'
 
It doesn't explain the issue of clone beers coming out less bitter though. If you are scaling down the recipe and using the exact same hops, then the bitterness should be the same, regardless of style guides or ibu calculation method.

IBU calculations are largely a waste of time worrying about, because the whole process through to packaging will alter the perception of bitterness, from brewer to brewer, beer to beer.
 
IBU calculations are largely a waste of time worrying about
I strongly disagree with this.

If you want to have any hope of brewing consistently then you need to know the IBU value.

If your beer comes out too bitter then you have a reference point to work from, likewise if it's not bitter enough. I know you could just arbitrarily add more or fewer bittering hops but that feels a lot like shooting in the dark and hoping to hit the bullseye. You are going to have a much better chance of success if you apply some science and logic to quantify how much you change.

It's also incredibly important when you factor in that even with the same type of hop the alpha acid content can vary significantly. One brew you might use a hop that is 9% alpha acids and the next time it may be 11%. Your IBU calculations are the best way to know how much you need to reduce the hopping rate by to account for the higher alpha acid content.
 
But it doesn't matter which method of calculation you use, to have that reference point. I didn't say they weren't useful, just they aren't worth worrying about. Simply, pick one method then adjust your bittering addition to taste. Bitterness isn't locked in at the boil, it can change with fermentation. So even if the calculator was 100% accurate at predicting hop utilisation, you'd still see variable results in the glass, using different yeasts, fermentation temperatures, dry hopping, attenuation, etc.
 
Last edited:
But it doesn't matter which method of calculation you use, to have that reference point. I didn't say they weren't useful, just they aren't worth worrying about. Simply, pick one method then adjust your bittering addition to taste.
Ok, maybe just a case of mis-understanding then as your previous post didn't make it clear that you were referring to the calculation method rather than calculating IBUs at all.

I agree that it doesn't matter too much which calculation you use provided you are consistent. Each method has it's pro's and con's and what is best for one person may not be the best for another brewer.
 
But it doesn't matter which method of calculation you use, once you have that reference point. I didn't say they weren't useful, just they aren't worth worrying about. Simply, adjust your bittering addition to taste.
I think the point is if some one wants to attempt a clone, we get the colour the ABV and the IBU's. The recipe is entered in Brewers Friend or which ever program is being used. If the IBU figure is relatively low the discrepancy is negligible but fi the recipe calls for an IBU of 40 then the discrepancy is 30 IBU!
Type in 70 IBU then the program being used will say to high. I have long thought there was a major flaw in the IBU's predicted I am just happy it has been pointed out.
Yes we can make adjustments as we go along but if we have a reference point where we know beforehand any discrepancies before we make up the recipe it is a bonus. Better still for the SMPH scale to be introduced on some of the recipe builders.
It is never going to be accurate, but by the looks of it a dam sight more accurate than some of the others.
 
I'm going to back @Sadfield here. Not because I know siding with him really confuses the hell out of him (we'll find something to have a slanging match about later), but because I do agree, the method of calculation provides a rough "reference point" to have an idea of the bitterness your beer is going to come out. If a group of you use the same calculation you can use the figure to share recipes.

If you use the all-singing, all-dancing, calculation that produces results closer to the laboratory results you can only share your results with others using the same calculation. If anyone else says "my beer comes out too bitter" or not bitter enough, then what can you say? "Well, that's because you're not using the X calculations, 'cos you're a dick". But who's the "dick"?


But throughout this conversation there's no mention of what is perhaps the most influential factor affecting bitterness: Hops age! If you make no attempt to allow for age, your calculations are as good as the proverbial chocolate fireguard.

This is a snip from Beersmith of a brew I made last year (2021):

HopAge1.JPG


They're old hops (coming up to 2 years). Take item 13; "Goldings (Aged 18 + 4 months) (2019) [3.31 %] ". They've been aged with the Beersmith built-in calculator (but widely available elsewhere) and are deemed to be 3.3% AAUs. Another note elsewhere states "Aged @ 5C for 18 months in oxygen barrier container: AA originally 5.5%. -18C thereafter. Aging calculated as of July 2021". The first figure (18 months) is a guesstimate of the treatment before I receive them, the second (4 months) for when I slam them in a freezer.

It does require a fair bit of fiddling, knowledge of the "Hop Storage Index" (widely published) and a bit of research to develop "useable" storage condition for the time before you receive them. But if I just used what was on the packet (5.5% AAUs) I'd be a tad disappointed about the resulting bitterness.


So, stop farting about with what "calculation" you use until you at least do things that really make a difference!
 
I'm going to back @Sadfield here. Not because I know siding with him really confuses the hell out of him (we'll find something to have a slanging match about later), but because I do agree, the method of calculation provides a rough "reference point" to have an idea of the bitterness your beer is going to come out. If a group of you use the same calculation you can use the figure to share recipes.

If you use the all-singing, all-dancing, calculation that produces results closer to the laboratory results you can only share your results with others using the same calculation. If anyone else says "my beer comes out too bitter" or not bitter enough, then what can you say? "Well, that's because you're not using the X calculations, 'cos you're a dick". But who's the "dick"?


But throughout this conversation there's no mention of what is perhaps the most influential factor affecting bitterness: Hops age! If you make no attempt to allow for age, your calculations are as good as the proverbial chocolate fireguard.

This is a snip from Beersmith of a brew I made last year (2021):

View attachment 70855

They're old hops (coming up to 2 years). Take item 13; "Goldings (Aged 18 + 4 months) (2019) [3.31 %] ". They've been aged with the Beersmith built-in calculator (but widely available elsewhere) and are deemed to be 3.3% AAUs. Another note elsewhere states "Aged @ 5C for 18 months in oxygen barrier container: AA originally 5.5%. -18C thereafter. Aging calculated as of July 2021". The first figure (18 months) is a guesstimate of the treatment before I receive them, the second (4 months) for when I slam them in a freezer.

It does require a fair bit of fiddling, knowledge of the "Hop Storage Index" (widely published) and a bit of research to develop "useable" storage condition for the time before you receive them. But if I just used what was on the packet (5.5% AAUs) I'd be a tad disappointed about the resulting bitterness.


So, stop farting about with what "calculation" you use until you at least do things that really make a difference!
and boil time lol.
 
I'm going to back @Sadfield here. Not because I know siding with him really confuses the hell out of him (we'll find something to have a slanging match about later), but because I do agree, the method of calculation provides a rough "reference point" to have an idea of the bitterness your beer is going to come out. If a group of you use the same calculation you can use the figure to share recipes.

If you use the all-singing, all-dancing, calculation that produces results closer to the laboratory results you can only share your results with others using the same calculation. If anyone else says "my beer comes out too bitter" or not bitter enough, then what can you say? "Well, that's because you're not using the X calculations, 'cos you're a dick". But who's the "dick"?


But throughout this conversation there's no mention of what is perhaps the most influential factor affecting bitterness: Hops age! If you make no attempt to allow for age, your calculations are as good as the proverbial chocolate fireguard.

This is a snip from Beersmith of a brew I made last year (2021):

View attachment 70855

They're old hops (coming up to 2 years). Take item 13; "Goldings (Aged 18 + 4 months) (2019) [3.31 %] ". They've been aged with the Beersmith built-in calculator (but widely available elsewhere) and are deemed to be 3.3% AAUs. Another note elsewhere states "Aged @ 5C for 18 months in oxygen barrier container: AA originally 5.5%. -18C thereafter. Aging calculated as of July 2021". The first figure (18 months) is a guesstimate of the treatment before I receive them, the second (4 months) for when I slam them in a freezer.

It does require a fair bit of fiddling, knowledge of the "Hop Storage Index" (widely published) and a bit of research to develop "useable" storage condition for the time before you receive them. But if I just used what was on the packet (5.5% AAUs) I'd be a tad disappointed about the resulting bitterness.


So, stop farting about with what "calculation" you use until you at least do things that really make a difference!
Quite obvious you haven't read any part of the link relating to the findings of Oregon State University and the author. Age of the hops is only a small part of what he covered.
There is a long list of other factors which has an effect on the conversion of iso alpha acids to the end result which a home brewer is looking for. A lot of work has been done in creating the SMPH scale no one is asking anyone to use it, or saying it is accurate but it seems it is a damn site more accurate as the graph shows using identical hops in identical wort at identical times and temperatures and pH.
 
For me it's the issue of still ending up being way out after fermentation and packaging, and then having to make adjustments based on your own sensory perception. So not really any better off. May as well dial in your bittering yourself on the styles that are an issue, than faff about with the multitude of calculators.

Theres a narrow range of beers in this, yet the difference of 20-40% loss in bitterness over the whole process.

https://www.researchgate.net/public...tages_of_the_Romanian_beer_production_process
 
... Age of the hops is only a small part of what he covered. ...
Is it? So, hop age isn't particularly important?

I'm glad I didn't waste my time reading that Oregon State University link then.



@Cheshire Cat: "Romulan ale was a strong, blue-colored alcoholic beverage created by Romulans. In the 23rd century it was illegal to possess in the Federation", sounds good (mine always come out green), have you a recipe?
 
Out of interest I checked the thread where someone had put my Amarillo smash recipe into Brewfather and it came out at 122 IBU. I then put the same recipe into the SMPH calculator and it came out at 66. It certainly tasted much more like a 66 than a 122! I know it doesn't really matter because it is what it tastes like rather than what a calculator says but it is a bit comforting to know that it is more likely to be a calculator that is out rather than me having a rubbish brewing technique (of course this might still be the case!).
 
Is it? So, hop age isn't particularly important?

I'm glad I didn't waste my time reading that Oregon State University link then.



@Cheshire Cat: "Romulan ale was a strong, blue-colored alcoholic beverage created by Romulans. In the 23rd century it was illegal to possess in the Federation", sounds good (mine always come out green), have you a recipe?
Recipe
Blue paraffin 60%
Paint brush cleaner 20%
Romulan water 20%
30 minute boil with EKG
Yeast Voss Kveik
 
I punched in the numbers from an 8.3% stout I made recently that Brewer's Friend said I had achieved 60 IBUs. This new model comes back with 40 IBUs. I will be making this stout again so I will use the SMPH calculator next time.
 
Out of interest I checked the thread where someone had put my Amarillo smash recipe into Brewfather and it came out at 122 IBU. I then put the same recipe into the SMPH calculator and it came out at 66. It certainly tasted much more like a 66 than a 122! I know it doesn't really matter because it is what it tastes like rather than what a calculator says but it is a bit comforting to know that it is more likely to be a calculator that is out rather than me having a rubbish brewing technique (of course this might still be the case!).
That example I showed above had a calculated IBU of 60. Had I not "aged" the hops it would have been 90. Beersmith using "Tinseth". (BTW: There isn't a lot of age effect once hops are crammed in a deep-freeze).

So, some merit using SMPH calculator? Shame it's not obviously "age" adaptable, but it does have a "freshness factor". The "freshness factor" needs a bit more emphasis, and certainly I'll be looking into it deeper...



But it's the same with "beer colour": We're stuck with what we've got for a while because it's too difficult to shake the nonsense out of the tools in wide use just now. So, work-a-rounds remain the best bet.
 
At first glance, the new SMPH method appears flawed to me. Compared with the ancient IBU equations, it most closely correlates with Garetz, which past experiments have long proved to be the LEAST accurate IBU calculation, and with Tinseth being the most accurate. If the new method was developed using aged hops, this might make more sense. But based on the old fashioned giggle test, I have little reason to consider this new method any more accurate than Garetz or Tinseth or any of the others. Data needs to be INDEPENDENTLY verified.
 
For me it's the issue of still ending up being way out after fermentation and packaging, and then having to make adjustments based on your own sensory perception. So not really any better off. May as well dial in your bittering yourself on the styles that are an issue, than faff about with the multitude of calculators.

Theres a narrow range of beers in this, yet the difference of 20-40% loss in bitterness over the whole process.

https://www.researchgate.net/public...tages_of_the_Romanian_beer_production_process
I agree at the end of the day we will adjust the hop charge to our own sensory perception, but we need to be somewhere close to what we are aiming for. As you can see 18-25 IBU the 5 scales are reasonably close as the IBU value goes up then the scales suffer in the forecast IBU, @ 44.3 Rager and @ 30.5 Tinseth while SMPH is @2.5.

I have recently found the same as others, Tinseth just doesn't produce the IBU's which are forecast once we can get somewhere in the ball park then we can make finer adjustments.
I wanted to make sure that the author isn't a home brew crackpot blogger so looked him up. You will find the full article from BYO replicated among his credentials.
https://www.google.com/search?q=joh...50l8.2168060648j0j15&sourceid=chrome&ie=UTF-8
Is it? So, hop age isn't particularly important?

I'm glad I didn't waste my time reading that Oregon State University link then.
Well if you had have taken the time to read it you would have noticed that he does mention the storage and hop freshness.

At first glance, the new SMPH method appears flawed to me. Compared with the ancient IBU equations, it most closely correlates with Garetz, which past experiments have long proved to be the LEAST accurate IBU calculation, and with Tinseth being the most accurate. If the new method was developed using aged hops, this might make more sense. But based on the old fashioned giggle test, I have little reason to consider this new method any more accurate than Garetz or Tinseth or any of the others. Data needs to be INDEPENDENTLY verified.
Another good reason to read the blogs on the link, the author mentions that Garetz is about 50% off course in the IBU range of 20 to 25 IBU's but makes up ground as the IBU's increase. None of the known scales have been independently verified, why should this one?
Figure 2 compares measured IBUs and predicted IBUs for the five models, with measured IBUs on the horizontal axis and predicted IBUs on the vertical axis. The straight dashed line from lower left to middle right indicates where predicted and measured IBUs are equal. It can be seen that on this set of data, the Tinseth, Rager, and mIBU models all have very large predicted IBUs for the higher-IBU beers. The Garetz model has a good fit with the higher-IBU samples, but predicts values about 50% too low in the range of 20 to 25 IBUs.


Figure 2. A comparison of measured and predicted values for five IBU models.
Other Considerations
Some people are more sensitive to bitterness than others [Reed et al., p. 215]. From what I’ve observed, people who are very sensitive to bitterness find it unpleasant, and therefore they don’t tend to drink high-IBU beers. Also, the perception of bitterness changes with each sip. Therefore, I wouldn’t worry much about minor IBU differences; getting somewhere in the ballpark is probably just fine.
 

Latest posts

Back
Top