Beersmith allows you to calculate IBU’s. But it includes three different scales, and on my most recent IPA, one said 88, and another said 120. I didn’t check the third. Why are these so different, and is one considered “the gold standard?”
I think Tinseth is the most universally used. Years ago, I was told that Rager was most accurate for partial boils and Tinseth for full boils. I use Tinseth and when I’ve had beers analyzed for IBU the results have been very close to what I get in Promash using Tinseth.
Tinseth also works well for me. I have converted kegs, so did Tinseth when he did his work. His is the calculator that was correlated to measurements.
There is the aricle Gordon wrote back in the Jan-Feb 2010 Zymurgy covering when he went to Sierra Nevada Beer Camp. Some guy’s data for beers measured there are in the article.
The IBU calculators may provide IBU estimates of over 100 IBUs. Such estimations are probably incorrect. Some people say that people cannot taste IBUs in excess of 100. Consequently I would go with 88 IBUs here.
But just because you can’t taste it doesn’t mean you can’t measure it. Admittedly, we generally taste our beers (!) but you can certainly have a calculated value above the taste threshold.
It’s not clear to me whether IBUs over 100 is a tasting issue or a chemistry issue.
You mean as a solubility issue? I’ll try to remember to ask John Maier about it. Rogue’s Old Crusty comes in at 110 IBU supposedly. it would be interesting to know how they arrived at that figure. I’ll also try to contact the lab that did the analysis or me and see what they have to say.
I remember hearing a recent interview on one of the brewing podcasts with someone from White Labs (Neva Parker, IIRC) saying that their highest reading in the lab was a beer from Mikkeller that was ~150 IBU’s. I’m wondering if it was their “1000 IBU” IIPA.
The highest lab measurement I have heard was 113 IBU. You do get into solubility limits above 110, and 110+ is hard to acheive.
time to bitter with dandelion
Didn’t Tinseh measure the IBUs of errors taken from the boil at different times? there is a loss on the order of 30% during fermentation.
I don’t use IBU estimation.
But when I did, I quickly learned that it its only useful to compare your own beers. you should base your estimated IBU target on past beers you brewed that had the desired bitterness.
Kai
Kai, that would be a good question for Tinseth.
I know that the numbers I got were for finished beer, and were pretty close to what the Tinseth formula said. Well except for the double IPA that was calculated to be very high in the 100 range, but tested at 67 IBU IIRC.
Here’s a visual representation of a couple of different IBU formulae. I like Tinseth because his curve looks like a classical chemical reaction.
It must have been an exchange I had with him a while back where he pointed me to the procedure he used. I just looked here: Glenn Tinseth's Hop Page and couldn’t find it.
An inherent problem for estimating beer IBU from AA amount and boil time (and maybe hop product type) is that beer IBU depends on many more factors. Some of the major factors that come to mind are:
- boil pH. It is known that higher boil pH extracts more bitterness
- bitterness lost during fermentation blow-off (I believe that this is a good thing)
- bitterness lost to yeast trub. I expect this to vary quite a bit
- non-linearity of bittrerness extraction. I.e one cannot extrapolate the bitterness extraction of a high AA concentration boil from low AA concentration experiments.
There is a reason why IBU calculators are largely a home brew thing. All the authors that came up with extraction formulas were home brewers. Without a doubt, there has been commercial research on that topic, but it has not yielded the extraction formulas that we are using. Commercial brewers do pilot brews and measure IBUs to correct the recipe or process.
If you know that a particular commercial IPA has 60 IBU, then this number came from actual IBU measurements and not from an IBU prediction based on the hop bill. If you like that bitterness and want to have it in your home-brew you may start aiming for 60 estimated IBUs, but you may have to correct the hops up or down after you tasted the beer.
I just think many, especially beginning brewers, trust these IBU calculators too much w/o knowing how they work and what their limits are.
Kai
I agree with what you are saying.
In addition, some yeast will take more of the IBUs out than others. The pH drop during fermentation does cause more to precipitate out. It is a wonder you can make predictions at all.
A brewery of a fair size can run the measurements and tell what the utilization is for their system. Sierra Nevada publishes their IBU numbers and I think you can use those as a benchmark - within production variations.
Homebrewers often try to calculate the numbers and obsess over it because they can. If one also knows that your perception can only discern a difference of about 4 to 8 IBUs (depending on who you read), then there is not much point in stessing too much over it.
I make beers with basically three levels of bitterness, 10-20, 40-50, 80+. I could probably tell smaller differences, but for my system, and my tastes, those are my rules-of-thumb for bitterness.
It seems to me that our concept of hoppiness is shifting away from IBUs and bitterness. Hopping a beer later in the process to make flavor/aroma bombs with a lighter emphasis on true “bittering additions” is a focus on hop oils and other delicates in hops. I wonder if the chest thumping around 100+IBUs bbers will eventually give way to oil content and some undefined future unit of aroma.
Just thoughts.
Kinda like how florists use International Prettiness Units to rate their flowers?