36 replies to this topic

[Yeasty Boy]

I have always, always done Tensith. I almost always feel like my IBU's are higher than I mean them to be, and it seems like Rager will calculate them lower.Thoughts?

[Darterboy]

I use Rager but for no objective reason other than that Jamil does. I think the thing to do is pick a formula and stick with it. It's not important to know exactly how many IBUs are in a beer but rather to be able to predict a certain level of perceived bitterness in your beer. Pick one formula or another and keep using it till you're familiar with the results you get and so can repeat your past successes and reliably adjust your misses.

[MyaCullen]

I have always, always done Tensith. I almost always feel like my IBU's are higher than I mean them to be, and it seems like Rager will calculate them lower.Thoughts?

good topic, as i have also always used tinseth, and am curious as to others thoughts on the different hop calculation approaches.Personally, I have a similar observation in that, it seems IBU's might be a tad more than I hoped.

[stellarbrew]

I use Tinseth only because that is what my palate is calibrated to. If I calculate 35 IBUs using Tinseth, then I know from experience approximately what to expect. What is calculated as 35 IBUs by Tinseth will be some lower number using Rager - if I knew how much lower intuitively, than I could use either system to equally good effect.As Darterboy points out, it doesn't really matter which you use as long as you are consistent for repeatability sake. Certainly neither method is an absolutely true method of calculated IBUs in your beer, just imperfect models for prediction.

[MtnBrewer]

Jeff Donovan, author of ProMash, has always contended that Tinseth is more accurate for full boils and Rager is more accurate for partial boils. I have nothing to back that up other than his opinion but I think it's a pretty informed opinion.This is speculation but it could be that for very bitter beers, neither calculation takes into account the saturation of alpha acids in the wort. As you put more and more iso-alpha acids in the wort, the less soluble they become. So at the upper end of the scale, true IBUs start to roll off until around 100-120 IBUs, no more can be dissolved. I'm pretty sure (but not positive) that these models don't take this into account. In other words, if you add enough hops, you can make the IBUs come out to anything you want even though it's not physically possible.

[dagomike]

I sent some beers out and none really matched any formula. I don't think it really matters except when trading recipes -- using the same is probably most likely to give the closest results. Lots of things factor into actual IBUs. Bottom line I think is to just use the same one. If it seem a calculated IBU is too bitter, just reduce the hops.

[chuck_d]

I have always, always done Tensith. I almost always feel like my IBU's are higher than I mean them to be, and it seems like Rager will calculate them lower.Thoughts?

Rager will usually calculate them higher. Rager's numbers are the generally the highest for utilization, while Garetz's the lowest and Tinseth usually falls inbetween the two. I use Tinseth because I've read in a bunch of places that it is supposedly more accurate.https://www.realbeer.../FAQ.html#units

[BrewerGeorge]

...This is speculation but it could be that for very bitter beers, neither calculation takes into account the saturation of alpha acids in the wort. As you put more and more iso-alpha acids in the wort, the less soluble they become. So at the upper end of the scale, true IBUs start to roll off until around 100-120 IBUs, no more can be dissolved. I'm pretty sure (but not positive) that these models don't take this into account. In other words, if you add enough hops, you can make the IBUs come out to anything you want even though it's not physically possible.

This is very true. It has implications for extract brewers, too, because the saturation limit applies at all times. This means that the most you can get in your 3 pre-dilute gallons is still 100ish IBU's. After you dilute to 5 gallons, you're left with just 60 IBU's in the final batch - no matter how much vegetable matter you piled in the pot.

[Kansan]

I like the Rager formula. I have had the pleasure of taking a few brew-session classes from him. His formula seems to work well for me on most all styles. Especially classic English and Belgium styles. If you are a west coast hop-head lover then you might find yourself looking for a few more ibu.

[ThroatwobblerMangrove]

Has anyone made any side by side plots of the two formulas? I'd be curious to see how different the predictions are. I wouldn't be surprised if the amount of difference was in the noise of all of the other measurements (hop amounts, AA%, water amounts, wort gravity, etc.).

[dmtaylor]

I've used Tinseth for 10 years because I always read it was most accurate. But I also used a hop bag for 10 years. So Tinseth is what I understand and perceive for IBUs, while using a hop bag. Then about 5 batches ago, I stopped using the hop bag, and as a result, the bitterness in these beers has been higher than expected. So I guess there really might be something to reduction in hop utilization when using a hop bag. Solution? I can either retrain myself to shoot for the lower end of the range for each style (not so easy), or I can switch to Rager, which will result in my software calculating less hops for me to use from now on. And besides, Jamil and JP use Rager so who am I to argue.

[chuck_d]

Has anyone made any side by side plots of the two formulas? I'd be curious to see how different the predictions are. I wouldn't be surprised if the amount of difference was in the noise of all of the other measurements (hop amounts, AA%, water amounts, wort gravity, etc.).

I think I saw something like this. I'll try to dig it up next week after the holiday, otherwise I can probably plot one.

I've used Tinseth for 10 years because I always read it was most accurate. But I also used a hop bag for 10 years. So Tinseth is what I understand and perceive for IBUs, while using a hop bag. Then about 5 batches ago, I stopped using the hop bag, and as a result, the bitterness in these beers has been higher than expected. So I guess there really might be something to reduction in hop utilization when using a hop bag. Solution? I can either retrain myself to shoot for the lower end of the range for each style (not so easy), or I can switch to Rager, which will result in my software calculating less hops for me to use from now on. And besides, Jamil and JP use Rager so who am I to argue.

I forget exactly which one of them mentioned it, it might have been Rager, but one of them had a not-so-well documented figure of I think 10% reduction in utilization when using a hop bag. Maybe I should include a checkmark in my brewing sheet for that, currently I try to use all leaf hops and toss them in unbagged.

[dmtaylor]

I forget exactly which one of them mentioned it, it might have been Rager, but one of them had a not-so-well documented figure of I think 10% reduction in utilization when using a hop bag. Maybe I should include a checkmark in my brewing sheet for that, currently I try to use all leaf hops and toss them in unbagged.

Personally I have been very skeptical that use of a hop bag had any detrimental effect on hop utilization, but what can I tell you, results are results -- my last several batches have been a little more bitter than anticipated. Maybe not by 10%, maybe it's only 5%. But somewhere in there.

[denny]

I have always, always done Tensith. I almost always feel like my IBU's are higher than I mean them to be, and it seems like Rager will calculate them lower.Thoughts?

I use Tinseth and when I've had beers analyzed they were within 1 IBU of what Promash predicted.

[stellarbrew]

I use Tinseth and when I've had beers analyzed they were within 1 IBU of what Promash predicted.

That's amazing, I would have never guessed that it could be that accurate. I'm sticking with Tinseth then.

[japh]

This is very true. It has implications for extract brewers, too, because the saturation limit applies at all times. This means that the most you can get in your 3 pre-dilute gallons is still 100ish IBU's. After you dilute to 5 gallons, you're left with just 60 IBU's in the final batch - no matter how much vegetable matter you piled in the pot.

Which is why the extract brewer's first upgrade should be a large enough kettle to do full boils.While we can measure all day long, perceived bitterness is somewhat subjective, so you have to balance how you think it tastes for you, regardless of equations.

[Yeasty Boy]

I use Tinseth and when I've had beers analyzed they were within 1 IBU of what Promash predicted.

That's remarkable. I had also read that Tinseth was going to work best for my system. I guess I just have to acknowledge that my palette likes lower IBU's than standard. I'm not talking IPA's of course, but the alts, hefe's, lagers where the hop bitterness is in the 20-35 range, always comes out as more.

[robert41]

here is a great read. All three formulas were empirically derived. If nothing else, the tinseth formula just looks sexy.Notice how the rager formula gets maxed only after 48 min and predicts a very high utilization percentageand how the Garetz formula would not increase IBUs "on paper" during the first 10 min so of the addition. That means if you were using this formula and you were hopbursting, you would not see any increase in IBUs in your brewing software or calculations. https://users.rcn.co...ewsl/t9509d.htm

[ThroatwobblerMangrove]

here is a great read. All three formulas were empirically derived. If nothing else, the tinseth formula just looks sexy.Notice how the rager formula gets maxed only after 48 min and predicts a very high utilization percentageand how the Garetz formula would not increase IBUs "on paper" during the first 10 min so of the addition. That means if you were using this formula and you were hopbursting, you would not see any increase in IBUs in your brewing software or calculations. https://users.rcn.co...ewsl/t9509d.htm

Tinsith definitely looks more like a function I would expect to see for utilization. The nerd in me wants to change my spreadsheet now! Where can I find a definition of the function?

[dmtaylor]

Maybe I'll just stick with Tinseth after all, and shoot for lower bitterness instead. Rager looks most bogus of all, and Garetz is flawed from the get-go because of course you get SOME bitterness if boiling less than 10 minutes. Tinseth all the way, baby. Thanks for the info. It confirms what I thought I knew for many years.