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34/70 Yeast Tasting Appley

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  • 34/70 Yeast Tasting Appley

    Hi Everyone,

    In the last couple of months our brewery has been getting back more then several complaints that random lager cans in packs are tasting "sour" while the rest of the cans they have are fine. In the last year and a half we got a new Krohns line where our DO in can is between 25-50 and TPO around 35-70. Numbers are quite low. I know that with this lager strain oxidation can cause an apple taste which I am wondering if people are perceiving that as sour.

    We have a library of the date codes and pulled a bunch and we do notice the apple but not sour. A couple were plated and nothing came back either. The pH was checked and it didnt seem off usually around 4.3-4.5.

    Has anyone else dealt with this? I want to say that it is a canning problem but I am wondering if this could also be a fermentation problem.

  • #2
    Green Apple flavor is most closely associated with Acetaldehyde which is a byproduct of yeast converting glucose to ethanol. It can also (re)form from oxidation of ethanol.

    Green beer, autolysis of yeast, and packaging oxygen would be the primary suspects. If this is only happening in specific packages, that points to a potential issue with a certain process, or even a specific filler head.


    • #3
      We do micro on the fermenter which we haven't been getting any lactic acid bacteria growing in there fermenters, nor to we tend to see anything in brite or cans. I am however looking to get the plates that the lab currently uses changed. Because of the strain I know it can actually be lagered a lot shorter as I spoke with someone from Fermentis not to long ago. We usually keep our core lager in tank for 17 days min. I do think it should go longer (personally) but thats not my call at this point. We have had some autolysis with covid happening and a head brewer that honestly doesnt have any background in yeast management. I have found that you don't taste that when you do sensory before beer is centrifuged to brite tank. I do think that it has some acid to it but not an unreasonable amount.

      I am going to go through all brewing, cellaring and packaging data to see what is correlates these batches. Im usually sensitive to acetaldehyde, as I found out in schooling.

      I guess the best way is to start from the beginning product and follow it through. Other people here think that just because of covid, people are drinking more and thats why we are getting more complaints, and while that could be the case I think this is an issue as well.

      Thank you for responding!


      • #4
        17 day lager?! Well I can see your problem...the beer is still VERY young. What is your primary ferment temp?
        Larry Horwitz


        • #5
          Are you saying people will complain about 1 can within a 6 pack? That sounds like possibly a single filler head causing an issue. Might try getting the sour cans back to taste next time if possible.