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Old 11-15-2010, 11:20 PM   #1
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Default Testing for Actual IBU's

Has anyone ever sent their beer off to be tested by a Lab for actual IBU's? I wonder if it is even practical from a cost perspective.

I have heard it mentioned on Brew Strong a couple of times, but I'm not sure if that is even available to us Homebrewers. I'd really like to get some actual numbers off of my beers so I could adjust them accordingly.

Just a thought

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Old 11-16-2010, 01:06 AM   #2
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there was talk about it on here several years ago. If memory serves me, it cost over $100 to have the testing done or something like that.

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Old 11-16-2010, 01:09 AM   #3
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Requires something akin to a mass spectrometer. Not cheap. I hate to be a naysayer, but estimation can sometimes be your friend.

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Old 11-16-2010, 01:42 AM   #4
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The American Society of Brewing Chemists method for IBU measurement involves extracting the beer to be tested with a solvent (octane??) and performing UV/Visible light spectrometry on the extract. The method is available on line somewhere, I once found it, and have since lost it again. It isn't too hard to perform if you are familiar with the general techniques, like I was 25 years ago.

Someone on one of the homebrew forums was offering to do the test a couple years ago, but I haven't heard of it recently.

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Old 11-16-2010, 11:58 AM   #5
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Quote:
Originally Posted by AiredAle View Post
The American Society of Brewing Chemists method for IBU measurement involves extracting the beer to be tested with a solvent (octane??)
iso-octane i.e. 2,2,4 trimethyl pentane

Two other reagents are required: 3 N HCl is added to the sample to lower the pH so extraction into the gasoline phase is enhanced and pipets are dipped in octanol in order to suppress foam formation so the volume of beer in the pipet can be accurately read.

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and performing UV/Visible light spectrometry on the extract.
Only one measurement is taken at 275 nm.


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The method is available on line somewhere, I once found it, and have since lost it again. It isn't too hard to perform if you are familiar with the general techniques, like I was 25 years ago.

Someone on one of the homebrew forums was offering to do the test a couple years ago, but I haven't heard of it recently.
A 10 mL pipet is dipped into octanol and shaken so that most of the octanol is thrown off. 10 mL of chilled beer are drawn into the pipet and transferred to a 50 mL centrifuge tube. 1 mL of 3 N HCl is added followed by 20 mL of spectrographic grade iso-octane. The tube is shaken vigorously using a wrist action shaker (though I know one guy who does this determination professionally who shakes by hand) for 15 minutes. If there is a slush in the tube, centrifuge until the iso-octane phase is separate. Pipet a couple mL into a quartz 1 cm cuvet and read against another quartz cuvet filled with iso-octane and a "minute" amount of octanol. The IBUs are 50 times the absorbtion at 275 nm.

I have done this for a few homebrewers in the past and still do it for a local brewpub I'm involved with. I guess I could resume doing it for others but I would probably would have to charge at least $25 to make it worth my while and I do not want to wind up doing bitterness determinations 40 hours a week.
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Old 11-20-2010, 04:22 PM   #6
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One could also use liquid chromatography and actually quantitatively measure each type of alpha acid (as well as beta acids), but it is cost prohibitive to set up an HPLC system in the brew room. Plus it's a PITA analytical technique.

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Old 11-20-2010, 04:48 PM   #7
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ASBC MOA Beer 23-C, "Iso-alpha-acids by Solid Phase Extraction and HPLC" is such a method. In addition to being more involved it underestimates, compared to Beer 23-A (the method I described in my last post), when the hops used are old or have been poorly stored and when certain extracts are used.

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Old 12-05-2010, 01:26 PM   #8
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I was wondering what work had been done with HPLC and Mass Spec with beer and found this http://www.biocompare.com/Articles/A...-And-Beer.html

See how bittering acids either survive (or don't) in beer - and how oxidation takes a very measurable toll on beer.

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Old 12-05-2010, 01:39 PM   #9
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Old 07-17-2012, 09:53 PM   #10
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I thought I might try to resurrect this thread rather than start a new one. I am going to start testing beers for a local brewpub as they get going and I have access to a spectrophotometer and have ordered 2,2,4 trimethyl pentane and octanol, and a friend is going to get me some 1N HCl.

I would like to establish that my protocol is working and if not adjust it such as the 'minute' amount of octanol and the mixing/temperature. I figured that Sierra Nevada Pale Ale with its 37 IBUs would be a good benchmark because of their excellent lab and batch consistency. Does anyone know if you have to let the carbonation come out of the beer? I thought I remembered from Chemistry CO2 reacted with water to form carbonic acid though the pH of beer is pretty low and carbonic acid pretty weak.

Also I thought it might be a good idea to take samples every 10 minutes after the hops are added to the first batches since there is so much discussion about how whirlpool additions vary with increased utilization because of alpha acid isomerization after flameout. I'd be happy to share this information though it would only be relavant to a particular system.

White labs has IBU testing advertised at $48 on their website, not a bad price.

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