[denny]

Ask him about IBU from whirlpool hops, please.

Already have...he hasn't studied it.  But this is another experiment we're working on.

[dmtaylor]

My biggest take away is that the shape of the curves predicted by Tinseth are correct. The actual predicted IBU may not be correct.

To me that means Tinseth is still very useful. In your brewery, overtime, you learn to correlate what Tinseth predicts with the bitterness you experience and then you can use Tinseth to guide recipe design with respect to bitterness.

Where things get difficult is trying to understand bitterness from brewery to brewery since Tinseth may predict the same number for two breweries but actual bitterness, according to the Igor results, can vary significantly.

Agree totally with all the above.  I finally got around to listening to this podcast.  Excellent information.

Tinseth says of Rager: "totally wrong".  I love that.   

Meanwhile he admits and understands why the results from his own formula are only good to plus/minus 30%.  Gem of a guy.  Great information.

[narvin]

I'm over here using the real ibu formula like... Huh?!?!..

W=  B ∗ V
      1000 ∗ A ∗ U

Where W is the total weight of the hops to be used in grams, B is the desired
bitterness in IBUs, V is the final volume of post boil wort in the kettle in liters,
A is the alpha acid content of the hops (4.7% AA means that A = 0.047), and
U is the assumed hop utilization.
For example targeting 16 IBUs and assuming a utilization of 28% (i.e.
set U = 0.28 and B = 16). Utilization will vary from system to system; if your
beer ends up too bitter, try raising the utilization to 30%, and if it ends up
not bitter enough try lowering it to 25%. For example, assuming your post boil
volume is 21 liters, your hops contain 4% alpha acids, and your utilization is
28%, you would use a total of 30 grams of hops.

Well, the point of Tinseth is to estimate utilization based on boil time, wort gravity and other factors, right?

[Big Monk]

I'm over here using the real ibu formula like... Huh?!?!..

W=  B ∗ V
      1000 ∗ A ∗ U

Where W is the total weight of the hops to be used in grams, B is the desired
bitterness in IBUs, V is the final volume of post boil wort in the kettle in liters,
A is the alpha acid content of the hops (4.7% AA means that A = 0.047), and
U is the assumed hop utilization.
For example targeting 16 IBUs and assuming a utilization of 28% (i.e.
set U = 0.28 and B = 16). Utilization will vary from system to system; if your
beer ends up too bitter, try raising the utilization to 30%, and if it ends up
not bitter enough try lowering it to 25%. For example, assuming your post boil
volume is 21 liters, your hops contain 4% alpha acids, and your utilization is
28%, you would use a total of 30 grams of hops.

Well, the point of Tinseth is to estimate utilization based on boil time, wort gravity and other factors, right?

The easiest parameter to manipulate is the "time divisor" (4.15) for utilization.

[denny]

I'm over here using the real ibu formula like... Huh?!?!..

W=  B ∗ V
      1000 ∗ A ∗ U

Where W is the total weight of the hops to be used in grams, B is the desired
bitterness in IBUs, V is the final volume of post boil wort in the kettle in liters,
A is the alpha acid content of the hops (4.7% AA means that A = 0.047), and
U is the assumed hop utilization.
For example targeting 16 IBUs and assuming a utilization of 28% (i.e.
set U = 0.28 and B = 16). Utilization will vary from system to system; if your
beer ends up too bitter, try raising the utilization to 30%, and if it ends up
not bitter enough try lowering it to 25%. For example, assuming your post boil
volume is 21 liters, your hops contain 4% alpha acids, and your utilization is
28%, you would use a total of 30 grams of hops.

Well, the point of Tinseth is to estimate utilization based on boil time, wort gravity and other factors, right?

Because Glenn only used whole hops, there is some debate about whether boil gravity or protein coating causes the reduced utilization.  I've spoken with him and our lab person to try to devise some experiments to try to get a handle on that.  He also stressed that kettle geometry was a large factor.

[Pricelessbrewing]

Because Glenn only used whole hops, there is some debate about whether boil gravity or protein coating causes the reduced utilization.  I've spoken with him and our lab person to try to devise some experiments to try to get a handle on that.  He also stressed that kettle geometry was a large factor.

Right, kettle geometry is going to affect surface area (I believe some of the oils will stick to the surface area after transferring), as well as the boil off rate. Currently tinseth uses the average gravity between preboil and postboil I believe, but the boil off rate will affect this as well and adapting tinseths formula for instantaneous gravity was one of the things I was working on before my UV-VIS testing wasn't available anymore.

I'm also curious on how fermentation affects it, testing wort IBU and fermented beer ibu. Does that impact change with attenuation, what about speed of fermentation? Does fermenting under pressure change that? How does boil pH affect it?

There are just so many variables that could play a role.

[klickitat jim]

It's seems to me that this IBU thing is almost an act of futility if we try to absolutely nail it down. The ingredient is biological and inconsistent by nature. So even if we found a pristine formula that worked every time, it's still only working on the AA numbers that apply to the plug pulled for the lab, not necessarily for the ounce we have in our hands. Not to mention a big question mark on exactly how that ounce was handled. Striving for an absolute in this part of brewing, especially at our level... futile!

Then, if you send every brew to the lab for spectography, your getting a numeric value, but how are you perceiving that bitterness?

I say pick a method of estimating and stick with it then adjust in the future to taste.

Edit: sorry, I just watched 5 minutes of news and it put me in a mood. Not your fault.

[denny]

It's seems to me that this IBU thing is almost an act of futility if we try to absolutely nail it down. The ingredient is biological and inconsistent by nature. So even if we found a pristine formula that worked every time, it's still only working on the AA numbers that apply to the plug pulled for the lab, not necessarily for the ounce we have in our hands. Not to mention a big question mark on exactly how that ounce was handled. Striving for an absolute in this part of brewing, especially at our level... futile!

Then, if you send every brew to the lab for spectography, your getting a numeric value, but how are you perceiving that bitterness?

I say pick a method of estimating and stick with it then adjust in the future to taste.

Edit: sorry, I just watched 5 minutes of news and it put me in a mood. Not your fault.

Agreed, with one minor exception.  When we sent the hops out for testing prior to sending them to the IGORs, they were really close to what they were listed as.  Not exact, but close.

[klickitat jim]

It's seems to me that this IBU thing is almost an act of futility if we try to absolutely nail it down. The ingredient is biological and inconsistent by nature. So even if we found a pristine formula that worked every time, it's still only working on the AA numbers that apply to the plug pulled for the lab, not necessarily for the ounce we have in our hands. Not to mention a big question mark on exactly how that ounce was handled. Striving for an absolute in this part of brewing, especially at our level... futile!

Then, if you send every brew to the lab for spectography, your getting a numeric value, but how are you perceiving that bitterness?

I say pick a method of estimating and stick with it then adjust in the future to taste.

Edit: sorry, I just watched 5 minutes of news and it put me in a mood. Not your fault.

Agreed, with one minor exception.  When we sent the hops out for testing prior to sending them to the IGORs, they were really close to what they were listed as.  Not exact, but close.

So, we know those hops were close to advertised. We still don't know about all hops. Point being, seeking IBU absolute accuracy is kind of a fools errand. Close enough is close enough.

[denny]

So, we know those hops were close to advertised. We still don't know about all hops. Point being, seeking IBU absolute accuracy is kind of a fools errand. Close enough is close enough.

Absolutely.  One thing that may help homebrewers get a bit closer to what they expect is the new packaging from YCH that includes HSI.  But like you say, it's still a SWAG.

[Frankenbrew]

I say pick a method of estimating and stick with it then adjust in the future to taste.

This is exactly what I was thinking as I read through the thread. Beersmith is my method, and it produces consistent results to my taste in my brewery. Some of my friends have commented that my IPAs aren't as bitter as I say they are, but they taste good to me. And, by the way, my friends aren't exactly boycotting my taproom on the basis of science.

[klickitat jim]

For home brewers, maybe even commercial, I think we'd be better served to use which ever calculation we choose  (sticking with one) and then when someone who is sampling the beer wants to know "how many IBUs" don't use numbers, just say low or medium low, or high, or very high, or whatever term best describes it. Or take the time to explain what is behind those pesky IBU numbers... good conversation piece.

On the other hand, telling them "47 IBUs" and hearing them say "hmmm, tastes more like 45 to me" tells you a lot about them lol

[denny]

For home brewers, maybe even commercial, I think we'd be better served to use which ever calculation we choose  (sticking with one) and then when someone who is sampling the beer wants to know "how many IBUs" don't use numbers, just say low or medium low, or high, or very high, or whatever term best describes it. Or take the time to explain what is behind those pesky IBU numbers... good conversation piece.

On the other hand, telling them "47 IBUs" and hearing them say "hmmm, tastes more like 45 to me" tells you a lot about them lol

Oakshire had Dana (the lab person we used) come in and take reading every 10 minutes throughout their boil.  That way they were able to develop a custom utilization curve so they know exactly how many IBU they're getting.  I imagine other breweries do the same.

[klickitat jim]

For home brewers, maybe even commercial, I think we'd be better served to use which ever calculation we choose  (sticking with one) and then when someone who is sampling the beer wants to know "how many IBUs" don't use numbers, just say low or medium low, or high, or very high, or whatever term best describes it. Or take the time to explain what is behind those pesky IBU numbers... good conversation piece.

On the other hand, telling them "47 IBUs" and hearing them say "hmmm, tastes more like 45 to me" tells you a lot about them lol

Oakshire had Dana (the lab person we used) come in and take reading every 10 minutes throughout their boil.  That way they were able to develop a custom utilization curve so they know exactly how many IBU they're getting.  I imagine other breweries do the same.

That would be the best way. But how do you deal with the problem that most breweries don't do that? So customers are used to the beer they drink that randomly claims X IBUs, and that beer seems different than the true numbers on the new beer. And round and round we go

You don't taste mill gaps.... I don't taste IBU calculators

[BrewBama]

I realize that the IBU number itself is based on each brewery and a correlation to what the drinker perceives. My question pertains to calculation of that number.

When I calculate in BeerSmith I get a wildly different number that in Brewer’s Friend.  I believe they both use Tinseth’s calculation but how are they 15 points apart? (I was not exact in my duplication but close enough to make the point):






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