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Diacetyl from SO4 or dry hop?

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  • Diacetyl from SO4 or dry hop?

    FIRST AND FOREMOST- this happens in baja, mex about 500 miles from me. i go down to brew, knock out, and pitch and then have to hand over the rest to the help on site. who have no real brewing experience to speak of, so bare that in mind.

    here's the recipe-

    88% GW pale ale
    6.5% gambrinus munich 28
    4.4% caraamber
    1.5% flaked barley

    OG was 60. IBUs in the 50s. fresh brick of yeast. didnt oxygenate as tank was empty(weekend brew), but this was also fresh dry pitch.

    long story short, orders got mixed up, border crossing issues, etc. we had to brew with what we had on hand. so we used s04 and c hops. wort tasted bit sweet from the kettle, as if needing to back off the dark grains but again, this was a bit of a forced situation.

    fermentation seemed to go fine, although im not very familiar with so4. they dry hopped, which should have happened with positive co2 pressure into tank to keep o2 out as hops were dropped into DH port. after i could come back around week 4 i got a diacetyl-type flavor from the beer.

    so going forward, i'm going to teach them how to test for it. but as for now, its too late.

    so, no way at this point to know if it was from the fermentation or was introduced by o2 in dry hop, correct?

    and is so4 a yeast that is more or less susceptible on average to diacetyl issues? if so, is warming/rousing advised?

    lastly- while the flavor i got was in the diacetyl sort of zone, there wasnt any richness/slickness/mouthfeel to the beer. could it have just been the combination of the darker malts and so4? i ask because personally i couldnt really discern if i was getting butter/butterscotch type flavors or more of a toffee/caramel type flavor. either way, it wasnt very good. we added some more hops, and even a bit of humuflour hop essence, which helped, but that finish was still wrong.

  • #2
    I have experienced a sort of diacetyl like flavor from CTZ used as a dry hop. It was an older lot,and when we moved to a new lot the problem was gone. Sent the beer out for testing and it was under half of the threshold for diacetyl.

    As for oxygen being the issue, you would need the Alpha acetolactate present, which yeast produce from a lack of valine in the wort. So two things to cure this, or at least test for it. They should be doing a forced D test on every batch prior to racking off the yeast. Another thing to look at is get some yeast nutrient, most wort has plenty of FAN, but sometimes it doesn't due to malt variance, so a dose of yeast nutrient for every batch should help with this.

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    • #3
      Interesting. I would not have assume it was possibly wort related as it was all barley. Have to check notes if we used nutrients. In any case, its cheap insurance.

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      • #4
        Thats what it is, cheap insurance. Typically it is only high adjunct brews that see this issue, but different malts have different levels of valine and isoleucine, which are the two amino acids that create VDK issues when they are biosynthesized vs metabolized. Just dont go too crazy with the stuff, too much FAN is associated with fusel alcohol production.

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