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grassy hop flavors and pH?

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  • grassy hop flavors and pH?

    I've been picking up grassy flavors in some of our dry hopped beers lately, and I'm beginning to wonder if it has more to do with beer pH and not the hops themselves. FYI - our typical contact time for dry hops is 3 days, so that shouldn't be the issue. Our knock out pH heading to fermenters is typically 5.2-5.3, and our terminal pH post-fermentation typically ranges from 4.4-4.6. After dry hopping, it's typically up 0.2, so finishing in the range of 4.6-4.7, occasionally even 4.8. So here are my specific questions:

    1. could higher beer pH contribute to a more grassy/vegetal expression of hops?
    2. what is your target post-boil kettle pH? what do you use to correct in the kettle?
    3. what is your target pH in the fermenter after dry hopping?
    4. does anyone add acid (phosphoric acid, lactic acid, other?) at dry hopping to counter the increase in pH? seems like this may be a good thing for hop expression as well as beer stability.
    5. what yeast-related variables might I consider to affect terminal beer pH (e.g. pitching rate, oxygenation, etc)?

    Thanks in advance for the input.
    Kevin Drake
    Alibi Ale Works
    North Lake Tahoe

  • #2

    I strive for a knock out pH of 5.2-5.4 but preferring the lower end of that range. Our english strain is a workhorse and usually is done fermenting in three days when we pitch 0.6mio cells per ml per plato. This gives us a finoshed beer pH of about 4.0. Our Ipa strain ferments down to about 4.1/4.2 in four days and then the pH goes up about 0.3 after dryhopping. I want my beers below 4.5 out of obvious reasons. When our knock out pH is 5.4 we do not always achieve that so we add acid in the kettle to get the wort ph down a bit.

    We see massive pH drops when
    - yeast is very healthy (fresh and viable >95%) - we see bubbling in the blow off bucket straight after we are done knocking out.
    - sufficient oxygenation
    - higher fermentation temps. We let our english beers rise up to 23.0C
    - pitching temp 19.0-20.0

    How the pH affects grassyness...I dont know to be honest with you.


    • #3
      Dryhop Details

      What temperature are you dryhopping at?
      Are you recircing the tank?
      How long are the hops in the tank and at what temperatures?
      Do you dump trub during cold conditioning?
      Which varieties are you having grassy problems with?
      Do you know if dose seems to change the intensity of grassyness.


      • #4
        Also, do the grassy flavors go away after a few weeks? It could just be that the beer is a bit young and the hops and malt flavors are still maturing. How does the beer taste after it clears? Are you happy with the aroma? Perhaps dial dry hop back if so and compare batches side by side.

        Our pale ale is 4.5%, 24 IBUs and get's .5 KG a BBL Dry hop via top port, sometimes sits for 7 days on the hops, sometimes more. up to 14 at times. I get a bit of grassyness most times off the sample tap but it seems to diminish after a few weeks after the beer conditions.
        Leigh Davison
        Head Brewer, Partner & Beer Alchemist @ Schoolhouse Brewery
        Windsor, Nova Scotia
        "The Beer with Class"