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Thread: Active Fermentation Dry Hop, pH, and the creep

  1. #1
    Join Date
    Mar 2017
    Tampa, FL

    Active Fermentation Dry Hop, pH, and the creep

    We've started playing with some active fermentation dry hopping and have noticed a few things that I wanted to see if anyone else has seen or has experience with:

    1) The dry hop creep, where your fermentation drags out towards the end, dropping .2-.1 a day for 5-7 days. We have tried dry hopping at different points of fermentation (day 2 of fermentation, half way through, with 1 plato left), but have seen this happen during each. Typically this is adding about 5 days onto fermentation before we are comfortable calling it "done." Not sure if this is due to decreased flocculation and therefore more contact with fermentables or if it is some type of interaction with glycosides. We use Wyeast 1056 and I'm leaning towards decreased flocculation, but curious about others experiences/information.

    2) A steady increase in pH after the dry hop. Fermentation is steady and we don't see a big jump until the end, but we have seen beers that are fermenting at a stead 4.3 pH jump to 4.7 or 4.8 within a day or two. Yeast viability and vitality all look fine and we don't see this on anything other than our active fermentation dry hops. At 4.8 pH (the highest I've seen) the beer passed sensory, plates/pcr, and was well received, but from that jump I expect something to be wrong. Not sure if it is polyphenols or some type of yeast/hop interaction that is causing the pH to spike. Again, no off flavors or contamination to speak of, but its nerve-racking to see those numbers and, from what I understand, hydrolysis of hop oils happens better at a lower pH.

    Any information or experiences of the like would be great. Thanks!

  2. #2
    Join Date
    Aug 2016
    London, UK

    Dry hop has been found to increase pH. I've started adjusting my boil pH down to 4.7 to try to compensate. Sounds like packaged beer should be below 4.4 - 4.5 to prevent bacterial growth. Hops only prevent growth of gramme positive; pH prevents gramme negative.

  3. #3
    Join Date
    Sep 2017
    Kalamazoo, MI, USA
    Hey there,

    I have been doing some research into this issue recently. We are calling this effect the Freshening Power of the Hop. By dry hopping we observe ABV increases beyond what was intended and expected based on wort production parameters.

    For some background information I will direct you to these papers.

    The first is from Brown and Morris and was written in 1893.

    The second is a follow up from J. Janicki et. al. where they recreate some of these experiments and dig further.

    Let me know if you have any questions and I can do my best to try and help answer them.

  4. #4
    Join Date
    Mar 2017
    Grand Rapids, MI
    Just as mentioned above, the increase in pH is indeed due to the presence of hop oils and/or plant matter that is introduced into solution. The pH increase will remain all of the way through conditioning and carbonation, and into the package. I primarily focus on brewing hop forward beers and specifically NEIPAs.

    The best way to address this is to bring down the pH of your casting wort. What I have found, and what research papers have supported:

    1. Dry hop quantity of 1.5 lbs / BBL = approx 0.15 increase in pH
    2. Dry hop quantity of 3.5 lbs / BBL = approx 0.35 increase in pH

    I recommend bringing down the pH of the casting wort so that after final ferm and dry hopping, you are between 4.1 -- 4.4.

    Also - try a different yeast if you want to employ better hop-oil / yeast biotransformation - such as Conan or London Ale.
    Viridian Brewing Company

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