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Thread: Intermittent filling of large FSTs

  1. #1
    Join Date
    May 2018
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    Cairo
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    Intermittent filling of large FSTs

    Hello fellow brewers,
    I'm facing a case in which the brewhouse capacity is 120-130 hl / brew and 6 to 7 brews per day and the fermentation tanks (Vertical & Horizontal) are of a 1200 hl capacity (normally filled to 960 hl only), in other words it takes 7 brews to fill up one fermentation tank & the wort gravity is 12 P (1048 Brewer Degrees).
    In this case do you dose all the yeast with the first brew like you'd do in a fermentation tank that's filled with 4 or 5 brews or is it better to divide the yeast between the first and the third or the fourth brew? also do you aerate the last brew or not?
    The problem we are facing right now is that the final beer smells too sulphury (alternates between SO2 & H2S), I would be grateful if someone has an insight on what the cause may be.

    What I'm thinking is that dosing all the yeast with the first brew (160 gm /hl for the full FST which means 1,2 kg yeast per hl of first brew) results in the yeast going very quickly into fermentation and thus the fermentation CO2 strips out the Oxygen dosed later with the wort out of the beer, however the fermentation speed and yeast health seems fine unlike what would happen if you have poor aeration. What do you think about that point?

    Thanks in advance,
    Anthony

  2. #2
    Join Date
    Mar 2003
    Location
    Minocqua WI
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    That's not really enough information to chase down a SO aroma. A strong fermentation will help drive off SO aroma rather than contribute to it. Are you using a lager yeast? How long is your cold conditioning? What strain? For instance Weinstephen Lager creates allot of SO but results in wonderful beer if you have the time to age it. Min. 4 weeks IMEO. Then there's bacterial SO aromas, lets assume your making clean beer though.
    Other sources are your malt choice and wort boiling - IE DMS.

    But towards your initial Question; batches on the same day all get aeration but not , ie the next day, after fermentation starts. If you are pitching enough yeast for 7 batches into one that is an enormous over-pitch. You might want to split it up during the day, as you are having zero lag phase and little yeast growth. No matter how you dose, I would pitch all on day one.

    A quick google found this article you might want to scan. https://www.morebeer.com/articles/su...pounds_in_beer

    If you don't have the lab - have some samples sent out to see what you have exactly - then start troubleshooting.

    Extra- why not make 14ish plato batches, topped with water, and get it filled in 5 turns? You'll have to do the math to fit your system. Save money and time with no perceptible change in flavor. I do this because of an undersized kettle. I boil then top off before the whirlpool, after getting a reading of the wort and calculating the water addition. 10-15% less batches to make the same amount of beer.
    Brewmaster, Minocqua Brewing Company
    tbriggs@minocquabrewingcompany.com
    "Your results may vary"

  3. #3
    Join Date
    May 2018
    Location
    Cairo
    Posts
    3
    Quote Originally Posted by Ted Briggs View Post
    That's not really enough information to chase down a SO aroma. A strong fermentation will help drive off SO aroma rather than contribute to it. Are you using a lager yeast? How long is your cold conditioning? What strain? For instance Weinstephen Lager creates allot of SO but results in wonderful beer if you have the time to age it. Min. 4 weeks IMEO. Then there's bacterial SO aromas, lets assume your making clean beer though.
    Other sources are your malt choice and wort boiling - IE DMS.

    But towards your initial Question; batches on the same day all get aeration but not , ie the next day, after fermentation starts. If you are pitching enough yeast for 7 batches into one that is an enormous over-pitch. You might want to split it up during the day, as you are having zero lag phase and little yeast growth. No matter how you dose, I would pitch all on day one.

    A quick google found this article you might want to scan. https://www.morebeer.com/articles/su...pounds_in_beer

    If you don't have the lab - have some samples sent out to see what you have exactly - then start troubleshooting.

    Extra- why not make 14ish plato batches, topped with water, and get it filled in 5 turns? You'll have to do the math to fit your system. Save money and time with no perceptible change in flavor. I do this because of an undersized kettle. I boil then top off before the whirlpool, after getting a reading of the wort and calculating the water addition. 10-15% less batches to make the same amount of beer.
    Hi Ted, thanks for the insight.
    unfortunately adopting high gravity brewing isn't an option due to lauter tun constrictions, I would have loved to go for that.
    We're using a Pilsner yeast, fermentation & maturation are normally about 14-16 days and then cold storage for another two weeks at least before the beer is filtered, the aroma isn't 100% SO2 it's more on the H2S side sometimes and our SO2 analysis is between 8 & 10 mg/l. I thought it may be Pectinatus but the micro results came out negative and to be honest the smell isn't too strong like that of a microbial infection.
    I think we can do a trial to divide the yeast between the first and the fourth brew, I'm guessing that such an overpitch will have the yeast giving out weird metabolic byproducts for a while (Mercaptans?) and maybe the fermentation isn't strong enough to purge out all what's in the beer.

    Thanks again,
    Anthony

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