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  • Double Batch Fermentaion

    We have a 7bbl system and are thinking about doing a double batch into a 15 bbl fermenter. We can only do one batch per day because of 300 gal electric HLT.

    My question is when do we add the yeast?
    When we fill the fermenter 1/2 way the 1st day or wait till the second batch
    is added on the second day?

    Cheers,

    Chuck Stuhrenberg
    Big Muddy Brewing
    Last edited by BigMuddyBrewing; 11-02-2009, 04:36 PM.

  • #2
    Hi Chuck,

    I've worked at two breweries who took two slight different approaches to double batches on subsequent days.

    Every brewery I have worked at or seen has pitched yeast on the first day. You do not want fresh, aerated wort, sitting in a fermenter waiting to be taken captive by any bacteria.

    I have seen breweries differ on whether or not to aerate the wort on the second day. I personally chose to only aerate on the first batch because by the time I had the second batch going into the fermenter, I already had fermentation. I did not want to oxygenate any beer. It was just my belief.

    So in conclusion, I would pitch the yeast on the first day and aerate at least on the first day. Best of luck to you.

    Cheers,
    James

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    • #3
      yeast

      Add it to the first batch, then pump the 2nd batch on top.

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      • #4
        As others have said - no problem with brewing on 2 consecutive days.

        When we did it (brewing 2 consecutive 15Hl lager batches into a 20hl & 10Hl FVs) we just over-pitched the first brew & didn't aerate the second.

        If you did want to brew x2 on the 1 day - you could maybe use the copper as an extra HLT? (& maybe pump it to an FV until it's needed to fill up the HLT?). Just a thought.
        cheers
        MikeMcG

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        • #5
          double brew

          I have heard that Rochefort in belgium brews one batch with appropriate cell count for the first, then waits 2days, brews another and aerates the second batch as well, I believe the theory that the refermention will use the oxygen and not cause oxidation is sound. and the yeast cell growth is enough for the second batch. no experience yet.

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          • #6
            Originally posted by IPAMEASAP
            Add it to the first batch, then pump the 2nd batch on top.
            Do you mean to pump the 2nd batch via the top of the fermenter?

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            • #7
              Thanks for all the great replies!

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              • #8
                we pitch the first batch and only aerate 1/2 way through the 2nd batch. usually you'll blow through the cip arm if you aerate all the way through the 2nd batch.

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                • #9
                  We will pitch in the first batch and aerate both. Don't forget the yeast need to mulitply to reach an appropriate density with the addition of the second wort, and in order to reproduce to that density they need to consume O2.

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                  • #10
                    Brewery 1: All single batch tanks
                    Brewery 2: When we needed to Quad brew, it was just a long day
                    Brewery 3: All tanks take 3 brews, sometimes all in the same day, sometimes brew once, and two more times a day or two later. The first two KOs get O2 and the last one gets 02 for the first half of the KO
                    Brewery 4: It depends on how many KOs it takes to fill the tank. If it only takes 2, then only oxygenate on the first half of the second KO. Every other tank (taking more than 2 KOs to fill, which they all do), gets no O2 on the last KO.
                    Fighting ignorance and apathy since 2004.

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                    • #11
                      I just tackled my first double batch a week ago or so, but I managed to get it done in a single day with similar HLT restrictions. I pitched enough yeast into my first batch for both, and aerated both batches. I believe when someone said pump "on top" they did not actually mean going in through the top of the fermenter, but to add it as you normally would into an empty vessel.

                      I'm brewing on a 10bbl system with about a 13bbl HLT and a slow electric heater. To get around the HLT capacity issue I did what mic_mac suggested. A bit more detailed -- I heated up a full batch of water in my boil kettle during my first mash-in. I transfered the water into an empty tank (in my case, one of my 10bbl brites) to hold the water until I needed it -- your temp will drop some during transfer and over time so I got it pretty hot (190-195 I think?). You could also top off your HLT with this water first before sending it to a tank, after mash in 1. In addition my heat exchange water discharge can empty into my HLT and with monitoring of my HLT temp and temp/volume of the discharge I could keep a pretty decent total temp and volume in my HLT. I had pre-heated my HLT as much as I could prior to the first knock out (but after the 2nd mash) and once my HLT temp dropped to temp for the 2nd sparge I sent the rest of my discharge water to the drain. I made one mistake which was costly to my water, otherwise I probably wouldn't have had to use my pre-heated water from the brite at all, but I definitely recommend having it. Timing was a bit of an issue since I was mashing in batch #2 as batch #1 was boiling, but I had it all plotted out by the hour/minute and it worked out fine. It made for a long day but it was fun and challenging and I was able to get 2 batches done in under 12 hours because of the overlapping batches, instead of 2 full days for the same volume.

                      I know this wasn't really what you asked and obviously each system is different, but I thought I'd share my experiences.


                      Dave
                      Saugatuck Brewing Company

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                      • #12
                        As far as oxygenation goes, think of it this way: If you had the ability to oxygenate the yeast before pitching (which I'm told is really the optimal way to do it, even though I've never tried it), you would only do it once for however many times you're adding wort. If you're pitching enough yeast for the entire combined batch, then oxygenation should only be needed to get through the lag phase where there is substantial aerobic metabolization. Once your yeast starts anaerobic fermentation (about 12-18 hours later) there's really no need for more oxygen.

                        It's for these reasons that I've always oxygenated wort if adding to a tank in the lag phase (generally within 12 hours of the addition of the first wort), but don't oxygenate when I can see good fermentation action.

                        Although many posts seem to agree with what I've just said, I'd be interested in hearing some of the theories behind some other techniques that were listed in this thread.

                        Cheers!

                        Comment


                        • #13
                          Originally posted by gabewilson50
                          ... If you're pitching enough yeast for the entire combined batch, then oxygenation should only be needed to get through the lag phase where there is substantial aerobic metabolization. Once your yeast starts anaerobic fermentation (about 12-18 hours later) there's really no need for more oxygen.
                          It's for these reasons that I've always oxygenated wort if adding to a tank in the lag phase (generally within 12 hours of the addition of the first wort), but don't oxygenate when I can see good fermentation action.
                          Cheers!
                          But adding the second batch of wort will throw the yeast back into growth phase and thus require additional oxygen. And there will be enough growth not to worry about O2 in the beer- plus theres the Co2 scrubbing action thoughout the rest of the primary fermentation, and the low dissolvablity of O2 At ferm. temps.

                          I like the tecnique of treating each batch as seperate brews in one fermentor-pitching yeast and oxygenating both. Otherwise you have one batch over pitched and oxgenated and the second one the Under pitched and oxygenated. Its about getting the correct o2 and cell count for the full batch- I dont think 12hrs is long enough to expect yeast growth to take care of the second wort addition.

                          I should mention also: Are we all doing cell counts w/ viability and using a metered O2 valve so we acctualy know whats going into each batch?

                          Lastly- this is a great technical disscussion but in the end its all about results: How much yeast growth are you getting? Is primary fermatation time correct or too long/short? Are you hitting your target FG and Ph? Is the esters/vdks and other Ferm flavors appropiate for the beer? is disolved o2 within specs? Are bacterial counts low? Do your lab work and record results- thats the best start at developing good work practices.
                          Brewmaster, Minocqua Brewing Company
                          tbriggs@minocquabrewingcompany.com
                          "Your results may vary"

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                          • #14
                            Originally posted by Ted Briggs
                            But adding the second batch of wort will throw the yeast back into growth phase and thus require additional oxygen. And there will be enough growth not to worry about O2 in the beer- plus theres the Co2 scrubbing action thoughout the rest of the primary fermentation, and the low dissolvablity of O2 At ferm. temps.
                            Adding the second batch of wort to a rapidly fermenting tank will not revert the yeast to a growth phase. It's the presence of oxygen that induces aerobic metabolism, not wort sugars. As long as there has been enough yeast pitched during the first batch (i.e. 2x what you'd normally pitch if you're doing a double brew), it will provide enough cells in the long run for the total fermentation.

                            You may or may not have to worry about O2 in beer due to some of the other reasons listed above, but if it's not necessary, why waste the O2 and risk it at all?

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                            • #15
                              We regularly brew into a tank over two days. We add O2 only on the first day (unless we are making a very strong beer, and then only if it is not bubbling strongly yet). And we pump the second days brew in through the racking arm to assure a good mix and quick fermentation.
                              __
                              Kushal Hall
                              Common Space Brewery
                              Hawthorne, CA

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