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  • Yeast harvesting issues - looking for iinput

    Pro brewing newbie here. Just wrapping up first round of beers in our new brewery. We are fermenting and carbonating/conditioning in jacketed 10bbl conicals with carb stones. No brite tanks yet. I am having some issues with dropping and harvesting yeast and looking for input.

    When I go to dump trub and harvest yeast I target 35F or lower and make sure there is only 2-3 PSI in the tank, then I maintain that head pressure by hooking up CO2 to the CIP arm. Several times I have blown beer out the bottom of the cone after only collecting ~1 gal of trub and early floccing yeast. So here are my main questions:

    1) what PSI are you maintaining while dumping trub and harvesting yeast? Is 2-3 PSI about right?
    2) roughly what total volume of yeast/trub are you dumping from the cone after a 10bbl fermentation, and approx how much yeast slurry are you harvesting?
    3) how much time does it take to dump (or collect) all yeast and trub from the cone of a 10bbl fermenter?
    4) is anyone out there using a rubber mallet to *lightly* tap the cone and loosen up the yeast before collection? (I know that nobody will "recommend" this practice but curious if anyone is using it with good results)

    I realize that the answers to these questions are very dependent on the amount and type of yeast pitched (I'm mostly using Wyeast 1728 - scottish ale), and it takes a careful visual inspection through the sight glass to determine where to make the yeast harvest cuts. Just looking for some rules of thumb to start with for average strength beer.

    Cheers, Kevin
    Kevin Drake
    Alibi Ale Works
    North Lake Tahoe

  • #2
    My experience...

    1) I keep as much natural carbonation as possible. That is about 13.5psi before crashing. And that head pressure does not diminish significantly after crash, in case anyone wonders about carbonating that way. It isn't practical. I think your 2-3 psi is too low. Why that low?
    2) Depending on beer and yeast, I'd guess we start by dumping about half a bucket (10 liters) the first day after crashing. Then a quarter bucket the next, and progressively less each day for a total of maybe 20 liters of thick yeast. 30 liters if it is really powdery. This varies considerably. Put the bucket in the cold room, and the next day the yeast has sunk to densely occupy only 50-75% of the bucket with clear beer on top.
    3) Slower is better. Very slow yeast flow is required for the yeast to slide down the cone. Going fast just punches a hole in the yeast. Sitting next to a bucket for half an hour is the hard part. But if you walk away to answer your phone, you'll find your entire batch of beer in the drain. Or the yeast flow slows to zero until you jerk around the valve. Shoot for minimum of 15 minutes. 30 is better.
    4) No. Never found the need for this. Especially when you'd be likely tapping the cladding and not the actual cone surface.
    Good luck!
    Phillip Kelm--Palau Brewing Company Manager--

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    • #3
      I think the problem is that you are pushing with CO2 and "rat holing" the yeast cake causing beer to push through. Try just using the 1-2psi you have on the tank and only cracking the valve 1/3 to 1/2, depending on how the flow looks. Slower is generally safer. It's not a race...

      How much yeast/trub I drop before harvesting is super variable from batch to batch, beer to beer at our brewery, so pretty hard to comment on your situation.

      Same thing with "how much time"... that's going to be super unique to your tank and your process.

      I wouldn't want to collect any yeast that is stuck to the tank that a mallet would free. That stuff will be the least desirable yeast to harvest viability-wise. It will also contain lots of trub and solid material that you don't want to be re-pitching into other batches of beer. The yeast you collect should be a creamy, silky, white consistency free of off flavors and chunks.

      You basically have to just feel this process out if you don't have a lab.

      Comment


      • #4
        Thanks

        Thanks gitchegumee and beersweeb for the input. I did cap the tanks at the tail end of fermentation and trapped 5-7 PSI of pressure. I decided to bleed some of that off (down to 2-3 PSI) before collecting yeast, but I guess I should have partially opened the dump valve rather than reducing the head pressure. Lessons learned.

        As for harvesting yeast for repitching...I do have a basic yeast lab setup so I can dial in proper pitch rates, check viability, etc. I may need to bite the bullet and order a fresh pitch since I'm not confident in the "cut" I collected this first round.

        gitchegumme - you gave me some rough volumes of yeast you collect each day following crashing. to be clear, are you repitching from the total amount of slurry collected over several days? I let all the yeast drop and settle for a couple days as I gradually stepped down the temp to ~35F, then tried to collect the center of the cone. That's what I've been taught by other brewers. Just curious what your harvesting approach is (versus simply dumping excess yeast).

        Cheers, Kevin
        Kevin Drake
        Alibi Ale Works
        North Lake Tahoe

        Comment


        • #5
          Repitching...

          The technique I described was for dumping, not repitching. If you wish to repitch, then suggest you do that after 24 hours of crashing and then take the fraction immediately following the trub that's dumped with the first yeast. Middle third of the yeast bed is what you want. Be sure to check it for cell density and viability.
          Phillip Kelm--Palau Brewing Company Manager--

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          • #6
            Figured I'd bump this thread instead of starting a new one since the subject is basically the same.

            From what I understand, just about everybody waits until after crashing to harvest yeast; however, we're doing a lot of lagers with a 3-4 day warm diacetyl rest (also under pressure) after hitting FG and I've always been concerned we're losing a good % of viability during this period. I need to get our lab setup so I can actually test it, but am I just over-thinking this?

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