# Why are we guessing at hop utilization percentage?

Here's a question...since you were able to dial in and predict IBU numbers as a result of arbitrary utilization settings, how did you go about deciding that X hop at Y time and temp yielded Z IBUs?
I didn't use arbitrary numbers, what I did was to brew a beer that the bitterness was set by boil additions, I then whirlpooled at 165F and followed the advice that no isomerization would take place below 180F. The beer was extremely bitter for a pale ale. I guessed at the IBU's and started using the whirlpool portion of the calculator. I then figured out that the rule of 180F was pure bulls*&^. My goal at the time and still is to brew a pale ale @ 35-40 IBU's with a lot of flavor and aroma. I ended up at about 3% utilization at 165F. If i were to raise the temperature I would have to raise that percentage. This is an example of the recipe. It's going to NHC finals for the third year in a row, it wins me a lot of awards and is a fantastic beer.

https://www.brewersfriend.com/homebrew/recipe/view/253526/wayner-s-pale-ale

I basically use the calculator to add the hops I want in the whirlpool and then I add the rest in the boil, which is usually cascade for 5-10 minutes depending on the targeted IBU's. In the recipe I just brewed I got @13 IBU's from the cascade addition, then I ignore the cascade addition from that point on. I figured it wouldn't contribute that much bitterness since the wort was chilled to 165F within 3 minutes of the end of the boil and it worked.

Each hop has an alpha acid percentage, that's the way you can adjust the bitterness in the whirlpool, if you add Galaxy @ 15% AA, the calculator will use the 3% utilization number to adjust bitterness. You have to watch your AA% in the whirlpool or the bitterness will get out of hand. The 180 rule is partly true, but not completely.

Compare bitterness with other beers that were of a known IBU number?
I was going for a pale ale, there is some wiggle room with bitterness, but the palate is the best way to estimate the bitterness. Mine lands somewhere in the middle of the style, some commercial beers are more bitter and others not as bitter. You know when your off, it just doesn't taste right, either too bitter or not enough. The palate is also fooled by the big aroma and flavor, so it may not be as bitter as one perceives.

For me it wasn't too hard and I'm happy with the results.

I guessed at the IBU's and started using the whirlpool portion of the calculator
That's what I mean by arbitrary...we have to assess the IBU contribution based on our subjective measurements using just our sense of taste. We can compare it to other beers and obviously we use the known characteristics like different alpha acids in different hops, but we're choosing to assign a value based on what we think is right.

A very interesting thread JA . Hop utilization is based on many different factors. Some good points have been brought up, but lots of ways of guessing for lack of a better word, how to measure how much you are getting. I have heard of spread sheet apps that give you figures for hop utilization, but I haven't found anything yet. If someone has come up with something that works maybe we could help the developers out on this?

I have heard of spread sheet apps that give you figures for hop utilization, but I haven't found anything yet. If someone has come up with something that works maybe we could help the developers out on this?
That was the motivation for my query...there must be a better way. We can use information like @HighVoltageMan! and others provide in description and recipes and start to get closer estimates about what time and temp factors provide a certain percentage of utilization. There's other information out there but it's pretty piecemeal.
I found a good article here:

Good article and it also shows as I stated we don't know enough about hops to create software formulas. We are still at a guessing stage and the recipe calculator we have is useable for each individual brewer. I think sometime soon there will be a breakthrough in understanding hops better as the universitys are working on it, but we are not there yet.

A very interesting thread JA . Hop utilization is based on many different factors. Some good points have been brought up, but lots of ways of guessing for lack of a better word, how to measure how much you are getting. I have heard of spread sheet apps that give you figures for hop utilization, but I haven't found anything yet. If someone has come up with something that works maybe we could help the developers out on this?
Call it empirical analysis. Sounds so much better than guessing and it does have some science behind it. The link to the Zymurgy article above gives the start of some science: The Rager equation for estimating bitterness gives whirlpool additions a 5% utilization. The default on BF is the Tinseth formula, which gives no utilization for whirlpool hops but we can select the Rager equation in the recipe editor. From the article, it looks like 4.5% is about the average utilization for hop stands, there was no perceived difference in flavor and aroma between the highest and lowest temperature and the lowest temperature had the lowest perceived bitterness. The IBUs contributed over time appears to be roughly linear, with around 4 IBU at 10 minutes, 5 IBU at 20 minutes and 5.5 at 30 minutes. The hop used was El Dorado at 14.9% AA. As far as the sensory evaluation goes, 10 minute hop stand was most flavorful and least bitter (I'll use that!), followed closely by a 10 minute boil. Pretty scientific to me: Hop stand for 10 minutes seems the best approach to me based on my preferences in beer. I'll start there, then experiment.

Last edited:
And the experiment starts today - I'm doing a Pale Ale, 3 gallons, OG 1.053, approx 30 IBUs per Rager, one gram of Magnum at 60 mins (foam control and protein coagulation - can't get around that!), 15 grams of Magnum at 15 mins, then a half ounce each of Centennial, Cascade, and Simcoe at flameout for 10 minutes. I may chuck in a half-ounce of some whole cone Crystal I have lying around at 180 degrees - it's an audible.

I've got 60 gallons scattered throughout the process in preparation for July 4th, but when I get a little caught up and get to brew again, I definitely want to do some basic research with this. It seems to me that doing several batches with identical grist and a single hop, one batch with all the hops at 60 and then other batches with additions at different whirlpool times/temps taking over for part of the bitterness and using a hop utilization factor that's fairly standard, that would give a basis for comparison in terms of subjective measurement, at least. Should be able to see if something is substantially different from the original batch and maybe make an estimate to help dial in which time and temp profiles match up with what sort of utilization rate.

Finished my first test a while ago.... One gram of Magnum at 60 mins to help with foam and coagulation, a charge of Magnum at 15 minutes, the rest in at 0 mins, whirlpooled for 10. From the taste of the wort, it seems the Rager equation got the bitterness about right. More to come as it ferments out.

J A
Just kegged up the IPA that started me down this path - Centennial/Columbus in heavy rotation late-hopping and dry hop. Being a very NW style where bittering is a big part of the flavor profile, it stood out to me to note that whirlpool hopping at the default rate pushed the IBUs way up there. When I had a taste of a gravity sample I thought that it might be a little off the scale but when I tried a carbed sample this evening after finishing fermentation and mellowing a little it seemed really nicely balanced. With the utilization set at around 3 or 4 and with some accounting for flameout hops left in for whirlpool and chill, the IBUs are computing at around 65 for an .060 beer. My palate is telling me that the number is pretty close but maybe just a tad high. I'll pick up a Sierra Nevada Torpedo that's a pretty consistent beer at 65 IBUs (though a little higher gravity) and do a little comparison.
PS... I love my IPA! Light Warrior bittering charge gives some pine and the Centennial throws a ton of floral/citrus on top of the Columbus funk. I threw in a couple of ounces of Amarillo in the dryhop along with the Columbus for this batch and though it cuts into the danky-stank I love so much, it lends a really rich aroma and flavor in the floral/soft-fruit part of the spectrum - call it a Strawberry Kush effect. Noice!!!

Finished my first test a while ago.... One gram of Magnum at 60 mins to help with foam and coagulation, a charge of Magnum at 15 minutes, the rest in at 0 mins, whirlpooled for 10. From the taste of the wort, it seems the Rager equation got the bitterness about right. More to come as it ferments out.
How do hops affect protein coagulation and foam issues?

Don't know the precise chemistry but I've read it somewhere.... Foam control for sure because of the oils in the hops, break formation likely because of the hop particles forming condensation nuclei for the break proteins.

• Pages
• Tools
• Search
• More