Alex, great stuff here, I used the forced VDK methodology early in my career and also teach this in my brewing Science classes at CSU. It is important to understand that this is a qualitative test, and accuracy is subject to the testers ability to perceive daicetyl, best to train with known concentrations across different brands. Another important aspect of this test is that it is imperative to filter out the yeast before heating up the sample as there is a high probability that the yeast will take up diacetyl faster than the conversion of a-acetolactate to diacetyl. In other works, if yeast is left in the sample it may result in a false negative. Cheers!
Original Message:
Sent: 03-10-2025 14:07
From: Alex Green
Subject: Developing actionable lab/QC practices on a budget?
Aside from post-packaging / archived samples, what other samples/data do you regularly collect? Do you have a DO meter? Depending on the size of your facility, I could see something like general fermentation tracking (daily gravity / pH measurements) being handled by either the head brewer or a dedicated QA/QC person. Beyond this, however, there are several easy low-budget assays that are easy to perform during fermentation.
One of the easiest and most useful processes you can implement is forced VDK testing. After primary fermentation is complete, I presume you are increasing your fermenter temperature by several degrees (VDK rest) to assist the yeast in processing residual diacetyl into acetoin. How do you know whether levels of diacetyl will actually stay below sensory threshold in the package? This is where VDK force testing comes in: take a sample of beer from the fermenter during your VDK rest phase and split it into two sample glasses (optionally, use a Buchner funnel/flask to filter/degas the samples). Cover the samples (I typically use a piece of heavy duty plastic wrap and a hair tie), set one aside (control), and put the other sample into a 140-160F water bath for ~15 minutes. Cool the "cooked" sample down to room temperature, and then smell the two samples side by side. The heating process will convert diacetyl precursors quickly into VDK compounds and, if enough precursors were present in the sample, this will be apparent as a buttery/butterscotch aroma or slick mouth-feel in the experimental sample (and hopefully not present in the control). After a sample "passes" this forced diacetyl sensory test, it should be safe to cold crash the beer (we typically make sure a beer passes two days in a row before crashing).
Beyond this, if you have access to a DO meter (Hach Orbisphere, Anton-Paar Cbox, etc), make sure you are using it to track oxygen pickup during tank-to-tank transfers and especially during packaging. You can test both kegs and canned products (with the right equipment) during packaging runs to ensure you aren't picking up excessive amounts of DO, and cross-reference this after the fact with your archived samples to see how this correlates with long-term package stability. You can also use a DO meter to verify whether a brite tank is adequately purged before filling.
Several other important and relatively easy/cheap lab/QA/QC tasks, in no particular order: collecting sterile samples during knock-out to verify you're not picking up any microbes in your HEX or knock-out lines, performing cell counts using a benchtop microscope and a special gridded counting slide called a hemocytometer to verify your pitching rates, using an ATP meter to verify cleanliness of surfaces / tanks / rinse water, using a hand-held O2 probe to ensure proper wort oxygenation during knock-out, titrating chemicals regularly to verify you are dosing at the correct concentration, regularly sending brewing water samples to a third-party lab to track variances in your water profile over time... the list could easily go on, depending on how many resources (time, personnel, equipment) you have to dedicate to your QA program.
Finally, I'd recommend getting a good book on the topic. Something like Quality Management, Essentials Planning for Breweries by Pellettieri is a good starting point (hopefully specific book recs don't violate any forum rules).
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Alex Green
Quality Assurance Manager
Black Tooth Brewing Co
Sheridan WY
Original Message:
Sent: 03-09-2025 14:01
From: Doug Kadzban
Subject: Developing actionable lab/QC practices on a budget?
Over the past 2-3 years, I've been slowly rebooting our QA/QC lab - drawing inspiration from a few MBAA podcasts we're collecting more library cans off the packaging line, and have modified how we do sensory panels to accurately gauge our packaged beers. Beyond that, I've started testing packaged beers in HLP tubes; and we've put a decent amount of time into tracking results in spreadsheets.
I've got a lot of good information, but it's only from the very end of the process, which leads to the concerns that our Head Brewer has: There's no practical way to use the data that we gather from our canned beer because there are SO many variables upstream from there.
I've heard that there are some resources online about building more functions into a beer QA/QC lab on a shoestring budget, but I've got no idea where to start looking. Can any of you share resources that you've found success with?
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Doug Kadzban
Holland MI
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