Hop Utilization/IBU Estimates

[GoodTimeCharlie]

I plan on brewing tomorrow but have a question on hop utilization. Beersmith calculates my recipe to be around 54 IBUs. YCH estimates the same recipe at 44 which is my target. Below is my rough estimates on additions. Target OG is 1.053.

My question is which calculator is more accurate. Proceeding with the wrong ratio will dramatically change the final product.

1 oz chinook @ 50 mins
1 oz chinook @ 10 mins
1 oz crystal @ flameout (~185 degrees) for 10 minutes
2 oz centennial @ 175 whirlpool for 5 min
2 oz centennial dry hop.

 

[Wayne1]

I plan on brewing tomorrow but have a question on hop utilization. Beersmith calculates my recipe to be around 54 IBUs. YCH estimates the same recipe at 44 which is my target. Below is my rough estimates on additions. Target OG is 1.053.

My question is which calculator is more accurate. Proceeding with the wrong ratio will dramatically change the final product..

Beersmith gives you three formulas to calculate bitterness of wort at the end of the boil. (Tinseth, Rager and Garetz) You should actually have your finished beer measured to determine which of the calculators comes closest to your actual brewing methods.
Remember, Beersmith is just simulation software.

The final IBU measurement of your beer after fermentation will be quite different.

Here is a post I made recently on ProBrewer:

All of the programs mentioned are just simulations. You need to run a few batches through your system and have them measured at a lab. That way you will know what the numbers actually are. Then you can correct the simulations to reflect reality.

In my last brewing job, I designed a beer in BeerSmith for 15 bbls. I adjusted the efficiency to reflect the OG/FG numbers we achieved. We moved to can production at a contract brewery that had a very complete lab. That allowed me to fine tune the numbers in BeerSmith to a greater degree.

As an example for an IPA. On brew day: OG:16, EBC: 21, calculated IBU 115. End of Ferment: OE: 15.77, FG: 1.009, EBC 22, measured IBU:90.3. In Brite, after dry hopping and fining: EBC: 15.8, measured IBU 71.2

So a calculated beer for 115 IBU calculated actually turns out to be 71 IBU measured post fermentation. A good lab and measurements are important to know what you are actually making.

 

[Silver_Is_Money]

I generally figure that none of the IBU calculators are going to get you to within better than perhaps +/- 35% of expected, and the general trend is to be lower rather than higher, though occasionally being higher also happens. Occasional results are off by as much as 70% vs. lab measurement. All bets are off for pellets though, as was explicitly stated by Tinseth himself.

 

[dmtaylor]

Need exact alpha acid % for each hop to be able to calculate this. Any calculator is only good to one significant digit anyway, so in that respect, the two calculations aren't far from one another anyway.

 

[GoodTimeCharlie]

Chinook is 12.8
Crystal is 4.8
Centennial is 9.3

 

[Blazinlow86]

I generally figure that none of the IBU calculators are going to get you to within better than perhaps +/- 35% of expected, and the general trend is to be lower rather than higher, though occasionally being higher also happens. Occasional results are off by as much as 70% vs. lab measurement. All bets are off for pellets though, as was explicitly stated by Tinseth himself.

I agree with silver. Pay close attention to your chilling times to avoid bitter bombs

 

[Vale71]

All three models have very little scientific evidence supporting them and can and will deliver wildly wrong results. Those who do not wish to spend money on actual IBU measurements (i.e. almost every homebrewer) should just stick with one formula and then adjust the targeted IBUs according to their taste impressions of the finished beer.

 

[thehaze]

Hop Utilization is different at lower temps. I whirlpool at 155-158F for around 20-30 minutes with a bit more than 3 oz every time, and I set my utilization at 3% using Brewer'sFriend. That gets me close - tastewise - every time.

With an OG of 1.053 ( only 2-row for simplicity's sake ) and calculating for a 5.5 gallons batch ( fermenter size ), you're looking at a 5.5% ABV aprox. with 70 IBUs. Those 2 ounces alone of Chinook at 50 and 10 minutes will give you around 60 IBUs and from experience, that is pretty close to what Brewer'sFriend estimates with a +/- 5 IBUs margin, but that still a lot.

 

[HTH1975]

I use Brewers Friend and find that I get less bitterness than I expect if I brew to style using the range on their preset styles. It’s all about knowing your setup and making adjustments to your own taste.

For instance, on a 1.045 OG bitter, with FG of 1.010 I will go for 40 IBUs in Brewers Friend. That generally gives a good middle of the road bitter with decent punch.

 

[mabrungard]

There are two factors at play here. The first is the estimation method and its assumptions and the second is the elevation where you're brewing. From my review of the three bittering estimation equations mentioned above, the Tinseth equation most closely follows the Malewicki and Shellhammer curve for alpha acid isomerization.

I find that Tinseth equation tends to produce a more bitter result in your finished beer. In addition, I find that the Rager equation more closely results in a beer bittering that corresponds to what the BJCP guidelines and many recipes tend to suggest. Therefore, I still use Rager. One good piece of advice that I think Zainasheff said, was that you should pick an equation and stick with it.

The second factor that most bittering equations don't take into account is the elevation at which you're brewing. As you know, elevation affects boiling temperature and that temperature affects the isomerization rate. Therefore, if a recipe was developed by someone brewing near sea level and someone living at a much higher elevation tries it out, that person at high elevation is not going to be pleased with the low bittering in the resulting beer. Conversely, if a high elevation brewer gives their prized recipe to a low-lander, that low-lander is not going to enjoy that overbittered beer. AHA members can review the slides from my 2018 presentation on wort boiling from the Portland conference to get guidance on how elevation affects hop utilization. Unfortunately you can't hear my discussion on wort boiling due to the screw up by the Convention Center staff.

 

[Vale71]

A third effect that they don't take into account at all is the effect of fermentation. Finished beer will have fewer IBUs than the wort they were made with, by how much is dependent on yeast strain and fermentaion vigor/PH drop. The largest difference is as usual to be expected when comparing ale and lager yeasts, with the former "burning up" more IBUs on average than the latter.

 

[dmtaylor]

Chinook is 12.8
Crystal is 4.8
Centennial is 9.3

By my calculations, assuming a 5-gallon recipe, you'll have about 79 IBUs. (By comparison, in my opinion @thehaze came closest to the real value, by whatever method he used.)

If this is instead 6 gallons, then that's 65 IBUs.

If 7.5 gallons, you have 52 IBUs.

I'm getting the impression that both calculators the OP used are a little low, assuming you input the exact alpha acid into your calcs. On the other hand, any calculations are only good to about +/- 10 IBUs at best (and I'm talking about Tinseth most specifically, as other equations all suck really bad). I don't know where the 35% thing came from, maybe Denny & Drew? That could be right too. Bottom line is that all these numbers are just ballpark values. Scientific laboratory experiments would be required to measure actual IBUs, and ain't nobody got time for that, or almost nobody. Sometimes good enough is good enough.

 

[Wayne1]

https://www.wardlab.com/brewers-services.php

Ward Labs does offer IBU testing for $16.00

 

[Silver_Is_Money]

I don't know where the 35% thing came from, maybe Denny & Drew?

That's where I first heard it. A podcast titled "The IBU is a lie." as I recall. Their various helpers made batches and sent them off for lab IBU testing, and most came within about 35%, but one was 70% low. That was also the podcast where Tinseth said "all bets are off" for calculating pellet derived IBU's with his math model.

 

[MaxStout]

Another variable is how the hops are added to the kettle. Do you add them directly to the wort, or do you use a hops bag, spider, etc.? In the latter case, there may be less AA finding its way into the wort. Beersmith has a utilization factor that can be adjusted. After a couple beers that tasted under-hopped, I set BS to a lower utilization and my unscientific palate tells me it's about right on. YMMV

 

[ncbrewer]

A partial boil limits the IBUs. Depending on who you believe, max possible is about 100. If you top up with an equal volume of water, then the max into the fermenter is about 50 IBU.

 

[BrewnWKopperKat]

A podcast titled "The IBU is a lie."

Episode 32 - The IBU Is A Lie | Experimental Homebrewing - https://www.experimentalbrew.com/podcast/episode-32-ibu-lie

See also "The IBU is a LIE! Kind of....." at https://www.experimentalbrew.com/experiments/writeups/ibu-lie-kind

To better get a handle on our brewers’ performances, we interviewed them to try and discover a through line. Here’s the big takeaway – remember the foreshadowing a few pages back about process – we think the “undershoot” is due to today’s more rapid chilling procedures than were common during the formula’s development [emphasis added]

Jeremy Wickham, whose APA and IPA entries landed close to target, disclosed that it takes him nearly an hour to chill his wort to pitching temps. (Like Drew he’s a victim of warm ground water temps.)

On the other hand, several of our under-bittered brewers revealed they have embraced the modern homebrew practice of chill hard, chill rapidly, get the wort cold yesterday. At least one brewer was also playing with a new electric rig that had a lower “boil” temp that possibly compounded the miss. (Denny doesn’t think this was the issue).

Is the model wrong? Or just being used incorrectly? If the 'wrong' model is used to make the estimate, but the estimate is useful (which numerous people in this topic have noted), is it really the wrong model?

Next, give Basic Brewing Radio November 1, 2018 - IBUs vs Wort Gravity and Hop Stand Temps a listen. Lots of good information on modeling and measuing IBUs produced during hop steeps / stands / whirlpools.

 

[dmtaylor]

Is the model wrong? Or just being used incorrectly? If the 'wrong' model is used to make the estimate, but the estimate is useful (which numerous people in this topic have noted), is it really the wrong model?

Any model is useful as long as we understand what it is modeling. The Tinseth model is particularly useful for those of us like myself who chill slowly over the course of 40-60 minutes, which I do via old-school submergence of the kettle in a cold water bath. Sure, if you chill super fast with a copper chiller or counterflow, you're going to see fewer IBUs. There is no official fudge factor for this, but you'll get fewer IBUs.

Furthermore, if you use whole hops, which I often do, Tinseth is great. Expect accuracy. But if you use all pellets, expect higher IBUs, and question whether the standard 10% fudge factor for whole vs. pellet hops is accurate, because it's likely not. Might be closer to the 35% thing that Click & Clack identified with their "Lie" podcasts.

The IBU is not a lie. The models are just misunderstood and misapplied. But still can be useful, with the right fudge factors. What those fudge factors are exactly is still in question though.

Cheers all.

 

[Silver_Is_Money]

This is the best dissertation on IBU's I've ever come across:

https://www.homebrewersassociation.org/attachments/0000/2501/IBUs.pdf

I used the formulas found within this document to make my own IBU spreadsheet.

 

[ncbrewer]

This is the best dissertation on IBU's I've ever come across:

https://www.homebrewersassociation.org/attachments/0000/2501/IBUs.pdf

I used the formulas found within this document to make my own IBU spreadsheet.

A really good read. Thanks for the link.