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

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.

Requires something akin to a mass spectrometer. Not cheap. I hate to be a naysayer, but estimation can sometimes be your friend.

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.

AiredAle said:

The American Society of Brewing Chemists method for IBU measurement involves extracting the beer to be tested with a solvent (octane??)

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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.

AiredAle said:

and performing UV/Visible light spectrometry on the extract.

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Only one measurement is taken at 275 nm.

AiredAle said:

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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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.

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.

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.

I was wondering what work had been done with HPLC and Mass Spec with beer and found this http://www.biocompare.com/Articles/ApplicationNote/1301/HPLC-MS-MS-Analysis-Of-Bitter-Acids-In-Hops-And-Beer.html

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

Link.

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.

Minute is indeed kind of iffy. For the pipeting of the beer the purpose is to prevent the beer from foaming in the pipet so the volume can be read accurately. It takes very very little. As I noted in an earlier post dipping the pipet tip in octanol, letting it drain and then whipping the pipet through a circular ark will throw most off. The MOA wants even this miniscule amount accounted for in the blank. I moisten the replaceable tip of a micropipetter with octanol and then just touch it to the side of the reference cuvet.

No - you do not decarbonate the beer. The MOA calls for withdrawing a 20 mL sample from cold, carbonated beer. The octanol takes care of the potential foam.

I would guess that the place where variation is greatest is in the extraction. See if you can find a used Burell Wrist Action shaker. Once you see one of these you will be convinced that this is what the people who wrote the MOA had in mind.

Thanks! If you want to test wort though, pre pitch, is it sitll the same protocol? I would like to be able to update them on their utilization from a single 20-30 minute addition....I'm hoping it's still under 100% and I can extrapolate backwards where the true bittering addition would be.

Yes, I would think so. Don't believe there is an MOA for wort though. Obviously you wouldn't need the octanol as there is no foam to deal with in the case of wort but it would probably be a good idea to use it anyway just to make sure everything is apples to apples.

I question the value of doing this to wort. I guess you could see how much additional boiling time increases the apparent IBU (remember this is a measure that 'adequately describes beer bitterness' not some absolute measure of mg/L isohumulone though it is apparently well correlated with that. Because of this fact and that utilization includes things that happen in the fermenter (i.e. the yeast strip a lot of bitter - ever wonder why Vegemite/Marmite taste the way they do?) I'm not sure that anything other than a relative interpretation is valid. Guess you could compare a just pre-pitch wort sample to a finished beer sample and scale all wort measurements back by the IBU ratio so determined.

Also keep in mind that a sample run is a fair amount of work (especially if you are shaking by hand). It takes about 20 minutes to do a test - longer if the dreaded 'slush' forms during extraction. This then has to be centrifuged, broken up and centrifuged again. Add another 5 minutes or so for that.

ajdelange said:

No - you do not decarbonate the beer. The MOA calls for withdrawing a 20 mL sample from cold, carbonated beer. The octanol takes care of the potential foam.

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I have had good and repeatable results using de-gassed beer and you do not need to mess with the octanol at all.

enricocoron said:

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

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Hopunion will do it for $20 now.

$40 for IBU, ABV, Color, pH and a couple other tests.

From Beer - 23A "Transfer 10.0 mL chilled carbonated beer (50°F) to a
50-mL centrifuge tube using a volumetric pipet that has
had a minute amount of octyl alcohol (reagent c) introduced
into the tip."

There is a reason for having standards: standardization. If you measure bitterness using the MOA and I measure bitterness using the MOA then people are comfortable with the notion that your measurements and mine are comparable. That's because in the process of developing the MOA several iterations of refinement and collaborative testing were carried out with the goal of getting the inter-laboratory (and, of course, intra laboratory) CV (coefficient of variation - the standard deviation divided by the mean) down. If an investigator can demonstrate that using warm degassed beer does not increase (or better still, decreases) the inter laboratory CV then he should write to the Standards Committee reporting his findings and proposing that the MOA be modified. This would (or could) result in another round of collaborative tests which, if they demonstrated that the CV was indeed not impaired or improved, would result in a modification to the published MOA. In other words, there is a reason that paragraph is in the MOA. If you are modifying the MOA for your own internal purposes then you can do as you wish but if you are charging people for analysis then it is incumbent upon you to follow the standard as closely as you can or at least inform your customers that you are not.

Beyond that using a little octanol is, IMO, a lot less trouble than degassing and find it interesting that foam always collapses too quickly in the glass and takes much to long to collapse in the lab.

Note: In looking back I see that I numbered the MOA incorrectly in a previous post. It is Beer-23. Also I indicated that N HCl is used. It is actually 3 N. The previous posts have been corrected.

enricocoron said:

Thanks! If you want to test wort though, pre pitch, is it sitll the same protocol? I would like to be able to update them on their utilization from a single 20-30 minute addition....I'm hoping it's still under 100% and I can extrapolate backwards where the true bittering addition would be.

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Beer-23 covers both wort and beer.

SPLASTiK said:

Hopunion will do it for $20 now.

$40 for IBU, ABV, Color, pH and a couple other tests.

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I know this post is several months old but I just contacted them (Alpha Analytics) and the pricing has gone up to $30 for the IBU testing. He said pricing has gone up for a number of tests but did not go into any detail

I haven't actually tried it yet despite having the reagents....White labs is down the street and after two results I have a fairly accurate constant I use along with Tinseth formula for my system. That is cheaper than WL though....