Ask The Brewmasters

  • 1.  tested oxygen decreasing over time by oxidizing the beer: how rapidly?

    Posted 03-07-2023 12:10

    Does anyone have a rough estimate of how many PPB per day of dissolved oxygen will disappear via oxidizing the beer itself? 
    -At room temp?
    -At cold crash temp?

    The reason I am asking is because we have seen slightly higher DO numbers in the bright tank for dry hopped beers that saw shorter and/or colder conditioning post-DH, and lower DO numbers for beers that saw longer and/or warmer conditioning post-DH.

    I am wondering whether that difference in measured DO is attributable to oxidation already having occurred in the FV, in which case the higher observed bright tank DO would be an illusion. Since there are some confounds in our processes that prevent an apples-to-apples comparison, I'd like to have a loose idea of the speed of oxygen reduction reactions in measured ppb.

    Would love your input and ideas.



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    Joe Grimm
    Brooklyn NY
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  • 2.  RE: tested oxygen decreasing over time by oxidizing the beer: how rapidly?

    Posted 03-08-2023 12:20

    Hi Joe

    Yeast presence and activity play a role here,  Active yeast can help scavenge oxygen pickup from ingredient addition.  A warm environment would likely have more active yeast and there is also a likely another small fermentation happening from dry hop creep that also aids in getting the oxygen taken up more quickly.  A cold environment may take longer for the yeast to take in that oxygen and also may be more difficult for the dry hop creep to occur.  I've observed very little to no oxygen reduction in a cold yeast-free filtered beer.

    It is hard to give you a rate of oxygen reduction due to the high number of variables from one brewery or one beer to the next.  In warm environments it does go down fairly quickly and our brewers try to take DO readings ASAP after a beer transfer as the numbers are typically lower a few hours later and we want to capture the peak level quickly to know if we have/had a quality concern.  Colder beers could be hours to days for reduction over time or not even reduce at all in my experience.  Hope that helps!



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    Louwrens Wildschut
    Pilot Brewery Lead
    Bell's Brewery Inc
    Galesburg MI
    (269) 250-8146
    lwildschut@bellsbeer.com
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  • 3.  RE: tested oxygen decreasing over time by oxidizing the beer: how rapidly?

    Posted 03-10-2023 12:15

    Thanks Louwrens, this is very helpful.  Are you able to give any specific numbers about how much reduction you are seeing over hours in this case?



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    Joe Grimm
    Brooklyn NY
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    Original Message


  • 4.  RE: tested oxygen decreasing over time by oxidizing the beer: how rapidly?
    Best Answer

    Posted 03-08-2023 13:01
    Edited by Joe Grimm 03-10-2023 09:37

    Joe:

    Of course you won't be surprised if I respond by saying, "It depends..."  But I'll start by giving you a concrete example from a beer that was packaged yesterday.  This is a flash pasteurized dry hopped IPA in 12 oz cans stored for one day at room temperature.  On the day of canning the shaken dO2 was 97 ± 6 ppb (n=2).  One day later the shaken dO2 is now 33 ± 13 ppb (n=2).  That's an oxygen consumption rate of 64 ppb per day.  However, the oxidation rate is probably exponential and dependent on the O2 concentration, so the rate will decrease over time until some asimptotic, stable concentration is achieved when the beer has become completely oxidized, likely leaving a measurable concentration of dO2.  That is, this particular beer will not continue to oxidize for the next 24 h at a rate of 64 ppb per day to a final O2 concentration that is less than zero, i.e. -31 ppb.  And if the beer had been poorly packaged with a higher shaken dO2 concentration the first day of oxidation would likely have been more rapid than 64 ppb per day.

    Hope that helps,

    Matt Cottrell



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    Matthew Cottrell
    Quality Manager and Microbiologist
    Heavy Seas Beer
    Baltimore MD
    (302) 430-3489
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  • 5.  RE: tested oxygen decreasing over time by oxidizing the beer: how rapidly?

    Posted 03-09-2023 13:36

    Hopping on what Matthew said.

    We test our TPO numbers minutes after packaging and  will see between 40-80ppb.  Just for the hell of it we ran cans the following day just to see the change and they were all under 20ppb.  These were stored at cooler temps, I assume if we left them at room temp it would have been 0.



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    Ivan Dedek
    Brewmaster/Food Scientist
    Meier's Creek Brewing
    Cazenovia NY
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  • 6.  RE: tested oxygen decreasing over time by oxidizing the beer: how rapidly?

    Posted 03-10-2023 16:08

    We have found the kinetics of the oxidation reaction to be very temp dependent.  We have seen BT DO numbers remain stable, in the low teens, for a week when the beer is kept at around 30F.  In a clear, west coast IPA with DH of 2.25#/bbl we saw the BT DO drop from 16ppb to 12ppb, while kept at 30F, in 7 days while we performed some unscheduled maintenance on our canning line (so about .5ppb/day).  Our warm stored (room temp) library cans go from about 50ppb to basically zero in ~3 days. 



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    Brian Logan
    QC/production Manager
    Bale Breaker Brewing
    Yakima WA
    (509) 424-4000
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    Original Message


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