IBU Calculations: Bug?

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IBU Calculations: Bug?

Postby biertourist » Wed May 12, 2010 6:14 am

Disclaimer: I'm a Beer Tools newb if it's possible that I'm using the tool incorrectly, it's highly likely.

How does Beer Tools calculate Bitterness (IBUs)?

Bitterness should be affected by the gravity of the boil, correct?
If I go into my current saved recipe, which lists an estimated 83.9 IBUs, if I add additional Dry Malt Extract to the recipe (Boil Kettle), the IBUs do not change.

If I go crazy and add 10 kilo of malt extract to a 5 gallon batch, the IBUs still do not change...


Am I doing something wrong? Is this a bug in 1.5.10? Does BeerTools just not take boil gravity into account when calculating IBUs?



Thanks,
Adam
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hop utilization and gravity

Postby slothrob » Wed May 12, 2010 6:39 am

It's probably due to your hop utilization settings.

Go to the menubar and select Recipe>Utilization. The pop-up menu will allow you to select a utilization formula to use for calculating the effect of wort gravity. I suspect you currently have "None" selected, but you want to choose one of the formulas named for the brewer who developed it.
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Postby biertourist » Wed May 12, 2010 6:39 am

I found the Overview on the Wiki which led me to the Utilization options.
I find it a very strange default that there would be NO adjustment made for wort gravity...
-Is there ANY even basic concensus over which utilization method is generally the most accurate for calculating beer with medium amounts of bitterness? (Are their any that are obviously not that accurate any more?)



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which formula

Postby slothrob » Wed May 12, 2010 6:52 am

I think the consensus is that you choose the formula that works for you. I know that's not very satisfying, but utilization can vary ±25% from one brewer's system to another. There's also some experimental evidence that gravity may not have much of an effect on utilization, other than a loss of IBUs to more hot and cold break at higher gravity. Of course malt selection and brewing technique can have as much or greater effect on the amount of break as gravity.

The closest thing I've seen to a consensus is that Tinseth is more accurate for a full volume boil, like that used by all-grain brewers, and Rager is more accurate for a partial volume boil, like that used by most extract brewers. I don't really know how valid that opinion is, though.

I use Tinseth, but I think I might actually get higher utilization than that formula predicts, particularly from late hop additions. If you use Brewing Classic Styles by Jamil Zainacheff and John Palmer, and want your recipes to match the book, JZ uses Rager.
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Postby biertourist » Wed May 12, 2010 10:46 am

Thanks, Slothrob!

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Just a calculator

Postby MNBugeater » Wed Aug 18, 2010 12:35 pm

The utilization calculators for IBU scales are just a reference calculator. It doesn't adjust how BTP is calculating in the recipe formulation. And it doesn't save what you set it at. If you close that window and go back in, it will be on default.

BTP does not allow you to adjust the calculation of hop utilization.

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Re: Just a calculator

Postby slothrob » Wed Aug 18, 2010 2:04 pm

MNBugeater wrote:The utilization calculators for IBU scales are just a reference calculator. It doesn't adjust how BTP is calculating in the recipe formulation. And it doesn't save what you set it at. If you close that window and go back in, it will be on default.

BTP does not allow you to adjust the calculation of hop utilization.

W

When you make a change, the modified utilization graph becomes the "Custom" utilization. If you click on "Use", it will apply those settings to the current recipe. If you click "Save", you can save the modified profile to a file. On future recipes, you can click "Load..." and choose that profile to apply to the current profile. Saving a Default with those settings should also make it available automatically when you create a new recipe. Saving as a Template would also allow you to apply them to an existing recipe.
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Postby MNBugeater » Wed Aug 18, 2010 4:40 pm

We obviously are looking at different things.

When I go to the Window Menu and Select Calculators i have Units, Color, Mash, %Until, S.G., %Atten., & CO2 options.

In selecting the %Util. calculator, I have a drop down labeled formula in which I can pick a host of scales, Rager, Tinseth, Fowler, etc. There is no 'Custom'. Additionally, there is no "Use", or "Save" button.

These are merely references and have no effect on the recipe.
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IBU calculations

Postby slothrob » Thu Aug 19, 2010 6:56 am

slothrob wrote:It's probably due to your hop utilization settings.

Go to the menubar and select Recipe>Utilization. The pop-up menu will allow you to select a utilization formula to use for calculating the effect of wort gravity.

MNBugeater wrote:We obviously are looking at different things.

When I go to the Window Menu and Select Calculators i have Units, Color, Mash, %Until, S.G., %Atten., & CO2 options.

Yes, we're talking about two different areas of BTP. The calculators you are talking about are independent of the recipe. I was talking about the Recipe>Utilization menu item. The settings, hop utilization formula choices and any changes made there directly affect the recipe.
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Postby MNBugeater » Tue Aug 24, 2010 11:35 am

Thats awesome. Thanks man. I have been looking for that forever.
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Utilization

Postby slothrob » Tue Aug 24, 2010 12:43 pm

Glad I helped!
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Postby mhochman » Thu Jan 06, 2011 9:40 pm

Sorry to wake up an old thread, but I have a question along these lines. I use hop pellets and I'm doing mostly partial mash batches. If I do the Rager, as suggested, for my other settings, what do I do for my pellet corrections?
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Postby slothrob » Thu Jan 06, 2011 10:53 pm

mhochman wrote:what do I do for my pellet corrections?

Fowler's a good choice.
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Postby mhochman » Thu Jan 06, 2011 10:59 pm

[quote="slothrob"][quote="mhochman"]what do I do for my pellet corrections?[/quote]
Fowler's a good choice.[/quote]

OK, great. Thanks so much!
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Hop Pellet Correction

Postby slothrob » Fri Jan 07, 2011 7:40 am

I don't think you'll go wrong with any of the hop correction formulas, they all add ~10% to the IBU contribution.
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