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  • Open Fermentation

    Would anyone have any book suggestions, or might be interested in answering some very basic questions about open fermentation? There doesn't seem to be much out there on it.

    I am specifically curious on how the beer is ultimately removed from the yeast? If it's drained from the bottom of the fermenter, is it done so with the intensions of leaving a portion of beer/yeast behind? And does that amount to a lot of wasted beer?

    I get the idea of fermenting with an open top, but the steps after that, I'm not completely following. At some point, I'm guessing that the beer goes into a brite tank. Does it have to be filtered before being transferred in? Is it possible to not filter it? Considering how old the process is, I'm sure it is, but if anyone has any experience, and can spell out real simple the steps to follow so that the beer can ultimately find it's way into kegs, it would be really appreciated.

  • #2
    Hi there,

    We have 5 open fermenters. They work fine but I would certainly prefer that all of our fermeneters were closed. The problem is, of course, that they are susceptable to infection especially in summer when the fruit flies are around. I never leave any beer in the open fermenters longer than 10 days. We had a couple of infected batches before we started following that rule (Acetobacter infections). Some breweries with open fermenters move the beer into closed tanks immediately after fermentation or even during fermentation.

    After fermentation we crash to 45 F for one day then crash to 33F. We'll harvest a pitch when the beer is at 45 or 33 F. The beer will sit at 33 F for 2-3 days during which we'll drop the remainder of the yeast. We do filter but you certainly don't have to filter. Cold crashing for a few days, a nice flocculent yeast, irish moss in the kettle, and finings, if you want, will give you a bright beer (not crystal clear but bright).

    Before we filter/transfer to a serving/brite tank we drop a 6 inch standpipe into the fermenter (We drop this length of pipe down a long stainless rod which guides the pipe into the hole. This can be tricky sometimes). This pipe sits in the drain hole at the bottom of the tank. The top of the pipe sits 6 inches above the bottom of the tank and above the bulk of any remaining yeast/trub. Our open fermenters are all shallow, dish bottom tanks so alot of yeast remains in the tank even after you've dropped as much as you can out the bottom drain valve. After dropping in the pipe simply open the main drain valve until brite beer comes out the bottom. Now you're ready to transfer to serving/brite tank. Of course when transferring the beer from an open fermenter you can't use pressure to push the beer. You have to pump it over.

    We have a 7bbl system and our yields in the serving/brite tanks are usually 7 bbls or close to it.

    Hopefully I answered a few of your questions. Good luck.
    Last edited by froptus; 05-27-2013, 10:59 AM.

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    • #3
      Re. open fermentation

      Howdy,
      I used to work in a small brewery as assistent brewer where we used an 30 hl open fermenter for two 12 hl brews. We only produced lager beer so I'm not familiar with ale brewing practice. During fermentation we used
      to remove some of the top of the ferment in order to be able to harvest cleaner yeast after racking. About 1 deg.P before end of fermentation , we'd crash the fermentation (3 deg C) overnight before we would transfer to young beer to a lager tank. we used a stand pipe to avoid picking up too much yeast. After transfer we'd carefully scrape of the toplayer of yeast which contains a lot of trub, dead yeast etc. Then we'd carefully scrape of and harvest the middle layer of yeast. The bottom layer is also not suitable for repitching. After all that, muggings had to go into the fermenter to clean it out by hand using a brush on a handle.
      Not much ful I can tell you !

      I have seen "open fermenters" which had hoods and a sliding door so they could be cleaned by cip. With regard to contamination, if you use a hermetically sealed space like a coolroom, you can use a HEPA filter
      to create a positive, sterile air pressure. In this case make sure you've got the means to remove CO2 before entering ! An exaust fan placed just above the floor will take care of that.

      If using top fermenting yeast I would imagine you could harvest yeast for subsequent fermentations from the top of the ferment. Aparrently yeast will survive a lot more generations using open fermenters. They are a lot cheaper to produce and hence buy. On the down side, they are not as practical to use so even a lot of "traditional" breweries have switched to cylindroconicals.

      If your budget won't strech to ccv's and you will use bottle/keg conditioning you can definately use open fermentation. It's been used for a long time !

      Cheers,
      JB

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      • #4
        Open Ale Fermentation

        One way:
        • Open fermentors in a closed two-level room, with air handling / filtration and CO2 monitoring upstairs and down (fruit flies may come regardless...).
        • Open fermentors are jacketed. Have one exit from the bottom center. Valve on end. Tank itself more-or-less dished bottom.
        • Fermentors also have an 1-2 foot wide opening near the top lip which coincides with being just above the wort surface. This can have a removable slide, leading into a smaller "yeast storage tank". This setup serves two functions: to give a place for kräusen to exit and run off during initial stages of fermentation, and -- after fermentation lets up a bit and you rinse the slide and yeast tank -- giving you a place to top-crop yeast into. Obviously the height of this opening is crucial to allowing both functions from your standard-volume brew(s).
        • From the top level, you can insert a standpipe of about 3-6" in length with a top metal ring on it, using a hooked extension pole. This is removable for later tank bottoms draining and cleaning.
        • Rinse down tank interior prior to knockout to remove any settled dust, etc.
        • Cooled wort in from knockout. Pitch yeast from over the top lip of fermentor after wort covers the bottom of the fermentor. Spectacular.
        • Set jacket temp, if you haven't already.
        • Ferment. Some ales can get through this stage within 24-48 hours ... so residence time in the open fermentor is less of a concern.
        • With about 1.5-2.5°P above terminal, top-crop yeast, but good! (This is its own skill, particularly knowing when it looks "right" for the particular strain, if the strain even lends itself to top-cropping). Yeast from this is generally light and fluffy, and extremely healthy. May vary widely depending upon strain. Some strains you might not be able to top-crop at all.
        • Let yeast pack down a bit in the yeast tanks, or cool these tanks to store yeast there for longer periods of time. If not, then run the yeast into your yeast storage vessels (whatever it is you use) and store for later use, or move to top level for subsequent batches. If you're dealing with open fermentors all side-by-side, you might have instead of top-cropping for storage, just rowed yeast from the top of one batch to the other, newer wort.
        • With about 1-1.5°P remaining to terminal, pump still-fermenting beer over to lager cellar.
        • You're obviously left with whatever bottoms are retained by the standpipe. This is waste. Obviously, you should have done a good job calculating the correct fermentor geometry and standpipe depth for your particular beer(s), so as to minimize losses but also to minimize sediment intrusion into what you just racked out into brites or secondary.
        • If your secondary or brites also have standpipes, particularly if these tanks are where you take the beer down to cellar temps, then you can retain even more sediment. Same could be achieved of course with a CCV.
        • Filtration not necessarily required. This is a call based more upon what you and your customer have "agreed upon" expectation-wise for your beers... Make more Zwickel Bier!
        • Cleaning: Remove standpipe from top level with extension pole. Wet sides of fermentor, but good, scratch down with plastic scrapers, clean tank thoroughly. Foaming machine helps here significantly. Surely more manual labor unless you could rig up some reasonable way to close the tank at the top a bit and CIP. You don't necessarily need to enter the tank for every cleaning, if you're effective with water, scrapers, foam, and brushes from the top lip. But occasionally, to remove beer stone, you might.

        This is one setup, and actually a more modern one at that. There's still lots of this being done in Europe, so figure it out before they all switch to fruit juice-pilsner mixtures!
        Last edited by NinkasiSwain; 05-29-2013, 03:07 AM.

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