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Thread: Spunding "too early"?

  1. #1
    Join Date
    Aug 2019

    Spunding "too early"?

    Hi everybody,

    The theory is to close the spunding valve approximately 1°Plato above the final gravity. Is it a problem if you close the valve before…even at the beginning of the fermentation? The spunding valve should regulate the pressure but I do not know if it would affect negatively the fermentation process.

    Greeting of the Swiss Alps!


  2. #2
    Join Date
    Mar 2018
    Amsterdam, The Netherlands
    I don't have an answer, but am interested in hearing what others have to say about it. For example, would DMS be more of a problem, since it might not be blown off with the CO2 as easily? Or any other off-flavours related to yeast stress?

  3. #3
    Join Date
    Oct 2013
    Hopefully you have removed the majority of DMS through boiling.

    3 things primarily in my mind. I am an advocate for spunding, but usually do it right after peak activity.

    1 - The off gassing produced by initial fermentation can be more than the spunding valve can vent, causing over pressurization of the vessel. Yes the pressure relief may be set at an appropriate level, but the gas production can be more volume than can be effectively vented second for second. Also, if there is blow off material from high krausen, it can clog a spunding device and cause a dangerous situation. By waiting until after high krausen you reduce that risk significantly.

    2 - Sulphur compounds. Usually they form early and are scrubbed out during the initial off gassing. They are not always present, but certain strains can be high producers. I personally like a slight bit of sulphur in certain lagers or hefeweizens myself, however it can obviously cause problems quite easily.

    3 - Yeast health can be impacted by osmotic stress, and fermenting under pressure does not particularly benefit any desirable yeast activity.

    Spunding immediately would risk stalled fermentation, deteriorated yeast health, excessive sulphur compounds, or possibly vessel integrity. Spunding late will risk under carbonation, and a need to introduce gas, possibly causing a time delay. To me personally, the risk-reward factor shows no benefit to trying to shave a day or two off the processing time at risk of product integrity.

  4. #4
    Join Date
    Jan 2003

    What Unfermentable said.

    Why would you do that? There is no upside. Only downsides. Normal SOP will treat you right.
    Phillip Kelm--Palau Brewing Company Manager--

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