diacetyl Quantification

[JoeV]

Does anyone know of any quantitative analytical methods/tests for diacetyl that don't involve GC/MC, HPLC, spectrophotometery? I am looking for something that would be more appropriate for a small craft brewery, with a basic lab.

Cheers,
Joe

[Todd]

Diacetyl

JoeV,

If you don't have a huge lab, the need to actually quantify your diacetyl, seems a bit unnecessary. I would recommend several approaches to detecting it and getting an approximation of diacetyl content. Flavor-active sells a kit with a diacetyl test, which would allow you to know at what level you, detect diacetyl. I would recommend getting a hand on this kit and determine yours along with several other staff members’ diacetyl thresholds. Everyone detects diacetyl at a different level. Once you know what level of detection you and your staff members have, you can determine if beers have excessive amounts of diacetyl. Chances are, not one of you will perceive diacetyl at the same level. Make sure to write these perception levels down, and if you perceive excessive amounts in your cellar beer, to have the guy with the highest perception level, check it against the guy with the lowest perception. If you have excessive amounts of diacetyl, you will need to rethink your VDK rest.

The one way to really perceive diacetyl in fermenting beer is to heat a sample of it up in a double boil on a hot plate in the lab. Use an Erlenmeyer flask to do this. Heat the sample up very slowly and bring it to about 70 C. Once you have reached that temp, dump the contents into a cool flask for your aroma test.

I hope this helps

[sbruslind]

Diacetyl measurement

JoeV;
Ask Gary Spedding at Brewers and Distillers Analytical Services (BDAS) and he'll tell you I am an evangelist for the ASBC Diacetyl method Beer-25B (Broad Spectrum Detection of VDK) It's old school wet chemistry at it's best. It requires a spectrophotometer, but not an expensive one as the sample gets read at 530nm which is in the Visible Range. Check out labX and eBay every week for used specs. Some are sub $500. If you think you're likely to want to spend the money contact us and we'll help vett the offers.
The beer analytical literature has references which frown on this method as it is prone to interferences and picks up more than just Diacetyl and 2,3 pentanedione; so readings can run a little higher than a GC Headspace method.
That's why I love it. I gives diacetyl potential and should correlate well to the heat-force testing/tasting that you can do right now. The detection level is 0.02 mg/L VDK, below taste threshold, so it can tell you well in advance if you're likely to have a diacetyl issue with your most perceptive clientele (who are usually the biggest-mouthed.)
You ask a great question and show intellectual curiosity about one of the fundamentals of technical brewing. I'm here to say it can be done, done well and make a difference in your process.
Keep it up. We have a lot of insight into this technique and we've shared with others who have asked. If you're serious we can help you with a reagent supplier list and an SOP, but it takes commitment.
Kind regards,
Scott Bruslind
Analysis Laboratory
Lebanon, OR 97355

https://www.analysislaboratory.com