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Filter Shock and Sweatiness

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  • Filter Shock and Sweatiness

    My boss brought up filter shock as a cause of a disjointed bitterness in our IPA directly post-filtration (luckily it goes away in about 24 hours or so), but said that he couldn't remember the chemical what-nots behind it. Anybody out there want to share some overly-complicated chemistry with the rest of us?

    Second thing: prior to filtering our Pale, it has a somewhat unpleasant sweatiness to it. I would call it raw, but I think that is just a response to pulling it straight from the fermenter. This was crash-cooled and the day of filtration. Post-filter, it had the weird bitterness that I described earlier (not to the extent of the IPA, but not the point), but after it was filtered, the sweat went away. Anybody have any ideas what's going on?

    Thanks for your help, and cheers,
    Bill

  • #2
    I have never heard the term "filter shock", but it does intrigue me. Are your beers dropping bright at all prior to filtration? How cold and how long do you crash? When you say disjointed bitterness, well i dont quite follow. Are your beers carbed at all in the FV, or not until BBT? I notice quite a change in hoppy beers from the FV (partial natural carbonation) -> BBT (finished via carb stone) which I have always attributed to the lack of Co2 - but i have not filtered an IPA in quite some time but did just start using finings again 2 batches ago.

    Sweatiness, the only thing I can come up with there is.. maybe autolyzed yeast? I always describe that as meaty or old bologna so not sure if it's the same thing. I assume you are dumping your yeast? I do, but I still have a couple spots where it accumulates, around the racking arm and behind the sample port (which is at the top of the cone). Because of this old yeast my samples from the perlick always have a bit of an autolyzed taste.

    Sorry no overly-complicated chemistry for you, I will leave that to the highly educated among us...

    "Pack of highly. Got it."
    Last edited by Jephro; 12-08-2010, 10:58 PM.
    Jeff Byrne

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    • #3
      Bill,

      Funny you mention this. I was just looking for some info on this earlier in the week. We filtered a batch of APA which always gets me thinking about it. We notice the same thing (sort of). I perceive it as a harsher bitterness, but the thing that really intrigues me is that the hop aroma is noticeably muted. But returns. The only explanation I have heard attributed it to colloidal shearing, whereby some compounds are sheared during the filtration and recombine over the next day or two. I'm not convinced this is the answer and have seen no data to back it up. It only seems to occur or is more noticeable on our hoppier beers, which makes me think it has to be hop related. I'm not sure "colloidal" would be the right term, but it does appear that some shearing explanation might hold water (beer). Hopefully someone out there can shed some light on this.

      Cheers,
      Travis
      Travis Hixon
      Blackstone Brewing Co.
      Nashville, TN
      travis@blackstonebrewery.com

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      • #4
        Could it simply be that during filtration the beer is very cold as compared to serving temps? Just a thought.

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        • #5
          Unfortunately, I don't think that it is a serving temp difference. The ferm holds the beer at -1C, and the bright does the same. Both are sampled into the same glass (cleaned and rinsed with 2C R/O water), and also sampled directly from the filter.

          Colloidal shearing? I like it...two words that make no sense together, yet sound like something that I could drop into a conversation to invoke envy in men and the lust of women. I'd certainly like to know if this is what is happening.

          As to the sweatiness, no, I don't think that it is autolysis. I was pulling half-gallon samples (it was a Friday, what can I say?), so I doubt that I was getting the built up yeast in the Perlick, especially since I blew out the first few ounces. The answer to this might be a little tricky.

          A quick aside: Jephro, that was a decidedly tasteful quote. Or should I call you "Citizen Snips"?

          Cheers
          Bill

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