Boil IBUS vs Whirlpool IBUS sensory analysis

[Mitch66]

Hi all,
I am opening a big discussion here, kind of more scientific but extremely important and practical to my opinion.
Hiw the same amount of IBUS from let's say, a 60min boil compare to the same IBUS coming from late additions or whirlpool?
My experience starts to show me that even if the ibu number is the same, the bitterness sense changes drastically.
Couldn't find any paper or similar subject. Any opinions?

 

[TheMadKing]

Hi all,
I am opening a big discussion here, kind of more scientific but extremely important and practical to my opinion.
Hiw the same amount of IBUS from let's say, a 60min boil compare to the same IBUS coming from late additions or whirlpool?
My experience starts to show me that even if the ibu number is the same, the bitterness sense changes drastically.
Couldn't find any paper or similar subject. Any opinions?

I'm no expert and you're getting into some complex biochemistry with hop oils. Here's what I think I know (please someone correct me if I say something wrong here)

I would start by understanding what IBU's are supposed to be, vs what is typically reported, vs what you are calculating in beersmith.

They are supposed to be the ppm of isomerized alpha acids in finished beer.

However when they are measured, they typically use spectrophotometry to measure the absorption of UV light at 275 nanometers. This measurement method reports a total light absorption, and does not directly measure the components of what is absorbing light at that wavelength (typically some combination of humulone, cohumulone and adhumulone). But Polyphenols and other compounds can also contribute to the light absorption and are therefore counted in the "measured IBU" value. So bottom line, IBU's are just a benchmark used for measuring the light absorption at 275nm, which correlates well to perceived bitterness FROM ISO ALPHA ACIDS.

Beersmith is calculating the best fit to a curve based on experimental models of measured IBU values for a given hopping rate. Now perceived bitterness also includes other compounds that are not iso-alpha-acids such as myrcene. IBU calculators do not account for these compounds well, so calculated IBU's do not correlate as well to perceived bitterness when late addition, whirlpool, and dryhops are used.

So using IBU's to try to measure perceived bitterness is difficult at best.

I would recommend listening to the Yakima Chief Hops podcast, Hop and Brew School. I have learned more about hops from that than almost anything else. But you are essentially correct that IBU and perceived bitterness can be VERY different, so it's best to judge dry-hopped and whirlpool beers by experience and not going by the IBU number.

 

[BrewnWKopperKat]

Welcome to HomeBrewTalk @Mitch66 !

 

[Mitch66]

I'm no expert and you're getting into some complex biochemistry with hop oils. Here's what I think I know (please someone correct me if I say something wrong here)

I would start by understanding what IBU's are supposed to be, vs what is typically reported, vs what you are calculating in beersmith.

They are supposed to be the ppm of isomerized alpha acids in finished beer.

However when they are measured, they typically use spectrophotometry to measure the absorption of UV light at 275 nanometers. This measurement method reports a total light absorption, and does not directly measure the components of what is absorbing light at that wavelength (typically some combination of humulone, cohumulone and adhumulone). But Polyphenols and other compounds can also contribute to the light absorption and are therefore counted in the "measured IBU" value. So bottom line, IBU's are just a benchmark used for measuring the light absorption at 275nm, which correlates well to perceived bitterness FROM ISO ALPHA ACIDS.

Beersmith is calculating the best fit to a curve based on experimental models of measured IBU values for a given hopping rate. Now perceived bitterness also includes other compounds that are not iso-alpha-acids such as myrcene. IBU calculators do not account for these compounds well, so calculated IBU's do not correlate as well to perceived bitterness when late addition, whirlpool, and dryhops are used.

So using IBU's to try to measure perceived bitterness is difficult at best.

I would recommend listening to the Yakima Chief Hops podcast, Hop and Brew School. I have learned more about hops from that than almost anything else. But you are essentially correct that IBU and perceived bitterness can be VERY different, so it's best to judge dry-hopped and whirlpool beers by experience and not going by the IBU number.

Hey, thank you for the reply mate! I know what you are taking about, I am just trying to be a bit more practical here. For example, I have brewed many west coast IPA recipes, where -while the total IBUS is at the 60-70ish mark and seem right- most of them come from late additions and wp. So, the finished beer is kinda sweet. On the other, I have tried recipes with the same or even less IBUS, but they come from a 60-45 min boil and the difference in perceived bitterness is enormous. Your experience and opinions are more than welcome brothers!

 

[CascadesBrewer]

Hey, thank you for the reply mate! I know what you are taking about, I am just trying to be a bit more practical here. For example, I have brewed many west coast IPA recipes, where -while the total IBUS is at the 60-70ish mark and seem right- most of them come from late additions and wp. So, the finished beer is kinda sweet. On the other, I have tried recipes with the same or even less IBUS, but they come from a 60-45 min boil and the difference in perceived bitterness is enormous. Your experience and opinions are more than welcome brothers!

My experience lines up with yours. If I calculate a recipe with 70 IBUs from a 60 minute addition, that beer will usually have a noticeable bitter backbone. For me that is more of a clean bitterness that builds up over 30+ seconds on the back center of my tongue. On the other hand, if my recipe software calculated 70 IBUs from mostly late hop additions, I would expect to perceive less bitterness. I will often get a different bitterness character; one that registers with me faster and it is often more of an astringent bitterness that I perceive more on the outer edges of my tongue. This is different than "hop burn" which hits me more towards my throat.

I would note that my girlfriend and I seem to perceive bitterness quite differently. A West Coast IPA that I perceive as mildly bitter is extremely bitter to her. An NEIPA that she says is smooth might have a strong harsh bitterness to me.

I agree with @TheMadKing about the IBU measurement and calculators. There is a difference between measured IBUs and Bitterness. The idea seemed to work fine with 20 IBU Pilsners and maybe even for classic IPAs with large 30 to 60 minute additions where isomerized alpha-acids were dominant. It does not work well with the massive amounts of hops added late boil like we see these days.

 

[Mitch66]

My experience lines up with yours. If I calculate a recipe with 70 IBUs from a 60 minute addition, that beer will usually have a noticeable bitter backbone. For me that is more of a clean bitterness that builds up over 30+ seconds on the back center of my tongue. On the other hand, if my recipe software calculated 70 IBUs from mostly late hop additions, I would expect to perceive less bitterness. I will often get a different bitterness character; one that registers with me faster and it is often more of an astringent bitterness that I perceive more on the outer edges of my tongue. This is different than "hop burn" which hits me more towards my throat.

I would note that my girlfriend and I seem to perceive bitterness quite differently. A West Coast IPA that I perceive as mildly bitter is extremely bitter to her. An NEIPA that she says is smooth might have a strong harsh bitterness to me.

I agree with @TheMadKing about the IBU measurement and calculators. There is a difference between measured IBUs and Bitterness. The idea seemed to work fine with 20 IBU Pilsners and maybe even for classic IPAs with large 30 to 60 minute additions where isomerized alpha-acids were dominant. It does not work well with the massive amounts of hops added late boil like we see these days.

Right? That's exactly what I am talking about. Lately, I was having a look on craft beer channel's west coast recipe, thinking of brewing it. However, from my experience, I could imagine that it is not going to have a good amount of bitterness, given their early additions which seems small for a westie. Generally speaking, how much bittering hops do you guys use for a classic punchy West coast IPA? Let's say for a 20lt batch

 

[TheMadKing]

Right? That's exactly what I am talking about. Lately, I was having a look on craft beer channel's west coast recipe, thinking of brewing it. However, from my experience, I could imagine that it is not going to have a good amount of bitterness, given their early additions which seems small for a westie. Generally speaking, how much bittering hops do you guys use for a classic punchy West coast IPA? Let's say for a 20lt batch

So I think you might have missed my point in my first post and I wasn't exactly clear so I apologize for that:

A beer with low calculated IBU's can taste much more bitter because of other bittering compounds in late addition hops. So while the IBU's ARE in fact low (and WHY that happens is due to the way IBU's are calculated), the PERCEIVED bitterness is high.

Hazy IPA's are a good example of this because they may have a calculated IBU of only about 25, but their bitterness may be must higher and on par with a 50-75 IBU west coast IPA.

So the higher you load up your hops into late additions and dry hops the lower your calculated IBU's will be, but that doesn't mean you won't get an IPA level bitterness.

For a west coast IPA I usually use about 1-1.5 ounces of bittering hops (added before 30 mins in the boil) and 3-8 ounces of whirlpool/dryhops.

For a NEIPA I use 0.5 oz of bittering hops or less and 8-12 oz of whirlpool/dryhops

 

[Gilbert Spinning Horse]

My version of BeerSmith (2) doesn't have a temperature setting for the whirlpool addition, so I really can't see how it can estimate the IBUs gained from that stage.

 

[TheMadKing]

My version of BeerSmith (2) doesn't have a temperature setting for the whirlpool addition, so I really can't see how it can estimate the IBUs gained from that stage.

Yeah that feature was added in BeerSmith 3 so it does a better job now, but it still isn't terrible accurate IMO, and it doesn't count dry hops for any bitterness at all, but you can make a 100% dryhopped beer and it tastes bitter, so that's clearly not accurate

 

[sibelman]

My basic west coast IPA (5 gal. 12 lbs pale + 1 lb. crystal) hopping schedule: early boil hops 2oz. ~7%, 2oz. ~7% late boil hops, various amounts of whirlpool hops (alpha acid often high but, I'm thinking, not important) when wort drops below 170°F.

Followed by dry hopping in the serving keg.

 

[Mitch66]

So I think you might have missed my point in my first post and I wasn't exactly clear so I apologize for that:

A beer with low calculated IBU's can taste much more bitter because of other bittering compounds in late addition hops. So while the IBU's ARE in fact low (and WHY that happens is due to the way IBU's are calculated), the PERCEIVED bitterness is high.

Hazy IPA's are a good example of this because they may have a calculated IBU of only about 25, but their bitterness may be must higher and on par with a 50-75 IBU west coast IPA.

So the higher you load up your hops into late additions and dry hops the lower your calculated IBU's will be, but that doesn't mean you won't get an IPA level bitterness.

For a west coast IPA I usually use about 1-1.5 ounces of bittering hops (added before 30 mins in the boil) and 3-8 ounces of whirlpool/dryhops.

For a NEIPA I use 0.5 oz of bittering hops or less and 8-12 oz of whirlpool/dryhops

Thank you for the reply friend!
I understand your point and agree with you. I am talking about the inversion of that. Let's say you have two ipas, with the same calculated IBUS, one from bittering additions and one from late additions. Forget about whirlpool or dh. The thing I am trying to say is that those two beers are going to have very much different perceived bitterness, despite the same calculated IBUS. In other words, like the late addition IBUS don't count the same as the early additions ones. At least at my experience

 

[Holden Caulfield]

My experience starts to show me that even if the ibu number is the same, the bitterness sense changes drastically.
Couldn't find any paper or similar subject. Any opinions?

kind of more scientific but extremely important and practical to my opinion.

You asked for scientific...

First, how did you determine that the realized IBUs in your beers were the same? Perception or IBU analysis.

Formulas that calculate IBUs are based on best fit curves from empirical data, they are only approximations, so your calculated IBUs may be the same but the realized IBUs may be very different.

Per this website, mIBU Experiments #1 and #3, the authors determined that the Tinseth model underestimates IBUs from late additions and whirlpooling and overestimates early additions. So depending on the alpha of the hops being used and the timing of the hop additions the actual IBUs may be different.

Furthermore, co-humulone % can also affect realized bitterness but not because it creates a harsher bitterness, as is often cited. Rather because it actually creates more bitterness. The scientific explanation for this can be found here...http://beer.suregork.com/?p=2377. Also here is a short article that provides the origin of the co-humulone harshness hypothesis...https://beermaverick.com/high-cohumulone-hops-myths-lists-opinions/

Finally, for fun, here is a Brulosophy experiment that puts high co-humulone hops against low co-humulone hops. As the actual IBUs of the different batches were never determined, but could be very different, this exbeeriment is basically worthless. That said, it is still a fun read that really goes to show how different peoples' perceptions are.

Bottom line - two batches of beer with different hops and hopping schedules with the same calculated IBUs may have significantly different realized IBUs. Whether that is due to just bittering levels or the co-humulone harshness effect, I will leave to others to debate

 

[hopfenstopfen]

Right? That's exactly what I am talking about. Lately, I was having a look on craft beer channel's west coast recipe, thinking of brewing it. However, from my experience, I could imagine that it is not going to have a good amount of bitterness, given their early additions which seems small for a westie. Generally speaking, how much bittering hops do you guys use for a classic punchy West coast IPA? Let's say for a 20lt batch

Check out this newish thread on the RR/CBC recipe.
Thread 'West Coast IPA (loosely based on Russian River Blind Pig)'

For what its worth, my pre-dry hop perceived bitterness was fairly high. Surely equivalent to >70 IBU beer with most hops coming before 30’ in the boil (think older versions of Stone IPA). Post dry hop, however, perceived bitterness fell off a cliff. I seem to remember reading conflicting info on dry hop contributions to perceived bitterness. Brew the recipe, but increase the 60’ addition & report back!

 

[TheMadKing]

Thank you for the reply friend!
I understand your point and agree with you. I am talking about the inversion of that. Let's say you have two ipas, with the same calculated IBUS, one from bittering additions and one from late additions. Forget about whirlpool or dh. The thing I am trying to say is that those two beers are going to have very much different perceived bitterness, despite the same calculated IBUS. In other words, like the late addition IBUS don't count the same as the early additions ones. At least at my experience

Yep what you have observed is well documented that perceived bitterness is very different based on when you get your IBU in the boil.

Let's explore what you are describing in the scenario above:

Two IPA's with 65 IBU's, one with most of those coming from early boil hop additions and one of those coming almost entirely from late boil (less than 15 min) hop additions. Lets call these Early Boil and Late Boil (shown below). Beersmith calculates the exact same IBU for both but Early Boil has 1.92 oz of Centennial at 60 minutes and Late Boil has 3.28oz of Centennial at 10 minutes.

These two beers will taste VERY different because in Early Boil all of your IBU are coming from the Isomerized Alpha Acids. Whereas in Late Boil there is the same amount of Isomerized alpha acids (based on the Tinseth calculations) BUT there is also a ton of other oils that haven't been driven off in the boil. I would expect the Late boil beer to taste more citrusy and less bitter (even with the same IBU), while Early boil will just taste like straight up harsh bitterness

 

[bwible]

Hey, thank you for the reply mate! I know what you are taking about, I am just trying to be a bit more practical here. For example, I have brewed many west coast IPA recipes, where -while the total IBUS is at the 60-70ish mark and seem right- most of them come from late additions and wp. So, the finished beer is kinda sweet. On the other, I have tried recipes with the same or even less IBUS, but they come from a 60-45 min boil and the difference in perceived bitterness is enormous. Your experience and opinions are more than welcome brothers!

You are describing the difference between two styles - New England IPA vs. West Coast IPA.

In general, the longer you boil hops, the more bitterness you extract from them.

“Old School” West Coast IPAs used mostly boil hops and we would follow a schedule with large additions at times like 60, 30, 15, 5. Then the beer would be dry hopped.

The development of IPA took further steps like putting the beer through more hops at cooling time, pushing the hot wort thru more hops on the way to cooling, using whats now called a hop rocket. Or it was called a hopback. I think Troegs still has a beer called Hopback Amber. Then people started pusing the beer through more hops at serving time. They had devices called a Randall or something like that. These contained hops and went between the keg and the tap.

Then they went to whirlpooling hops before cooling. All in the name of trying to get more hop flavor.

Somewhere people went to the idea of using almost no boil hops and putting all the hops at flameout and whirlpool and dry hop, This coincided with the rise of new varieties of hops from places like New Zealand. These hops create alot of haze. The style started somewhere in the New England area and they called it New England IPA. And they continue to get crazier with it.

There has been further confusion due to so many beers being canned now and you can’t see what’s in the can. NEIPA is not always labelled as such. When you see the words “juicy” or “dank”, and especially “hazy” then assume NEIPA. They also mostly taste strongly like grapefruit. West Coast IPAs also can have some grapefruit but are also described as “piney” or “pine cone” because for the most part they use American hops not New Zealand hops. NEIPA looks like a glass of orange juice. West Coast IPAs can be slightly hazy but many are clear beers.

Two different beers made by different processes.

If all this is not enough, some companies are making IPL, India Pale Lager now - and now we have discussions how lager yeast and the lagering process changes all this.

 

[bwible]

BU:GU and OG to FG also play a part in perceived bitteness.

https://learn.kegerator.com/how-to-calculate-perceived-bitterness/

 

[Mitch66]

Yep what you have observed is well documented that perceived bitterness is very different based on when you get your IBU in the boil.

Let's explore what you are describing in the scenario above:

Two IPA's with 65 IBU's, one with most of those coming from early boil hop additions and one of those coming almost entirely from late boil (less than 15 min) hop additions. Lets call these Early Boil and Late Boil (shown below). Beersmith calculates the exact same IBU for both but Early Boil has 1.92 oz of Centennial at 60 minutes and Late Boil has 3.28oz of Centennial at 10 minutes.

These two beers will taste VERY different because in Early Boil all of your IBU are coming from the Isomerized Alpha Acids. Whereas in Late Boil there is the same amount of Isomerized alpha acids (based on the Tinseth calculations) BUT there is also a ton of other oils that haven't been driven off in the boil. I would expect the Late boil beer to taste more citrusy and less bitter (even with the same IBU), while Early boil will just taste like straight up harsh bitterness

View attachment 770678View attachment 770679

Hi! That's EXACTLY what I am talking about. I just couldn't find any paper or articles on that. Anyway, my experience shows the same thing!

 

[Mitch66]

Check out this newish thread on the RR/CBC recipe.
Thread 'West Coast IPA (loosely based on Russian River Blind Pig)'

For what its worth, my pre-dry hop perceived bitterness was fairly high. Surely equivalent to >70 IBU beer with most hops coming before 30’ in the boil (think older versions of Stone IPA). Post dry hop, however, perceived bitterness fell off a cliff. I seem to remember reading conflicting info on dry hop contributions to perceived bitterness. Brew the recipe, but increase the 60’ addition & report back!

Thanks for the reply! Did you brew the exact same recipe? I can imagine it didn't come out as bitter as it should, regarding the style. How much hops (and what hops) would you put for a 60min addition at 20liters batch?

 

[hopfenstopfen]

Thanks for the reply! Did you brew the exact same recipe? I can imagine it didn't come out as bitter as it should, regarding the style. How much hops (and what hops) would you put for a 60min addition at 20liters batch?

The recipe I brewed was close, though not exactly what was provided on The Malt Miller site. I had to use different maltsters' versions of pale ale and munich. I also opted for 3ml of Columbus extract at 60' rather than the 15g of Chinook as listed. I should note that I use Beersmith rather than Grainfather for recipe formulation and, with the AA of hops I actually used, BS calculated 92 IBU.

 

[VikeMan]

The recipe I brewed was close, though not exactly what was provided on The Malt Miller site. I had to use different maltsters' versions of pale ale and munich. I also opted for 3ml of Columbus extract at 60' rather than the 15g of Chinook as listed. I should note that I use Beersmith rather than Grainfather for recipe formulation and, with the AA of hops I actually used, BS calculated 92 IBU.

Not to throw another wrench into the discussion... but 92 Tinseth computed IBUs is never going to be anywhere near 92 real IBUs. Above about 65 IBUs, utilization curves flatten considerably (which Tinseth doesn't account for). It's why BrewCipher provides a standard Tinseth answer and a "modified" Tinseth answer.

 

[Alan Reginato]

Just a small contribution. The whirlpool addition must be 5 to 6 times bigger than 60 min boil, for the same IBU. So there's going to be more quantities of hops compounds in wort, including beta acids, polyphenols, and it's going to be a very different beer. It could be hard to compare.

Check out this article

http://scottjanish.com/zero-hot-side-hopped-neipa-hplc-testing-sensory-bitterness/
Other compounds present in hops make a distinctive play in overall bitterness.

Many of them will be extract in late additions.

 

[hopfenstopfen]

Not to throw another wrench into the discussion... but 92 Tinseth computed IBUs is never going to be anywhere near 92 real IBUs. Above about 65 IBUs, utilization curves flatten considerably (which Tinseth doesn't account for). It's why BrewCipher provides a standard Tinseth answer and a "modified" Tinseth answer.

Timely article in latest BYO issue for a piece of this discussion : A modern method for calculating IBUs
Does BrewCipher use this or a similar model? I only recently discovered the blog.

 

[VikeMan]

Timely article in latest BYO issue for a piece of this discussion : A modern method for calculating IBUs
Does BrewCipher use this or a similar model? I only recently discovered the blog.

I hadn't read the BYO article (until just now, via your link). My modified Tinseth model (I had to look, but it was incorporated back in 2013) is not really similar (mechanically) to the article author's model. What I did was essentially graft a new utilization curve onto the Tinseth curve above 65 IBUs (based on a comparison of measured to theoretical IBUs). Mechanically, it's a little more complex than that, but that's the idea.

What is similar is that the article's author found that standard Tinseth predictions vs actual measurements get further apart the higher the predictions get.

 

[BrewnWKopperKat]

Timely article in latest BYO issue for a piece of this discussion : A modern method for calculating IBUs

Additional information (and code) here:

• GitHub - jphosom/alchemyoverlord: learning gitub
• AlchemyOverlord : experiments in beering
• IBUs and the SMPH Model

 

[CascadesBrewer]

Timely article in latest BYO issue for a piece of this discussion : A modern method for calculating IBUs

A very interesting article.

I have not read the referenced blog post. The article seems more focused on calculating bitterness with a "standard" hopping schedule, like for a Pilsner or classic American IPA. There is not a lot mentioned about hops from steeps/whirlpool additions. In fact the article put "the use of a hop stand" in the list of factors "that often have only a medium impact on IBUs." Some of my recent batches only had hops in a steep, and I have to think the time and temp had more than a "medium impact" on the bitterness.

This is where I struggle a bit. These days there are many hops in the 15% aa or above range. Adding several ounces of these very late in the boil or in a whirlpool/steep can really jack up the calculated IBUs. I use BeerSmith with Tinseth (cuz it is the default one). I think it calculates higher IBUs for my classic IPAs than I really get, but I have a general idea of what to expect from a calculated 40, 60 or 80 IBU beer with a more standard hopping schedule. I had a few batches recently with large hops at flameout or in a 180F steep that came out less bitter than I wanted.

 

[BrewnWKopperKat]

Timely article in latest BYO issue for a piece of this discussion : A modern method for calculating IBUs

I did an initial read of the article (IBUs and the SMPH Model) at the authors web site.

Thanks for sharing the link!

---

some additional reading / listening

• Basic Brewing Radio: November 1, 2018 - IBUs vs Wort Gravity and Hop Stand Temps
• Scott Janish: his web site + The New IPA.

Beyond that, I really need to dive really deeply into the material before saying much more.

 

[BrewnWKopperKat]

... but just a little more.

First, this (link) which may have much of the following "built in".

And now (just two items) this. Tinseth used whole hops. The data in the BBR podcast (mentioned above) covers measurements using pellet hops. A couple of years back, I put the data into a spreadsheet and played with the data.

The "x" axis is a relative IBU extraction efficiency number. The "y" access is time (in minutes). While there's nothing worth putting into an equation, it seems to capture why "15 min pale ale" and "Hop Sampler" work with pellet hops.

Data for the "BBR" line is from p 12 of the PDF associated with the podcast. Data for the "Classic Tinsenth" line is from from the "original" web page.