Yeast quantity

Discussion in 'General Brewing Discussions' started by Weardend, Mar 1, 2018.

  1. Weardend

    Weardend New Member

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    Hi. Just brewed an ESB which should come out about 5.4%abv. Target gravity has already been achieved in 2.5/3 days. I'm going to leave it for a while longer and then put in in the garage to cold crash and clear before barrelling.

    Not concerned about the beer I'm sure it'll be ok. Just concerned I've over yeasted. The yeast calculator on here suggested 29g of dry yeast to ferment for a 24l batch and given the speed that seems to have been too much.

    Has anybody got concerns/doubts over the yeast calculator on here. I'm summising 1.5/2 packets of yeast would have been enough rather than the 3 I pitched.
     
  2. jeffpn

    jeffpn Well-Known Member

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    I would’ve used one packet of yeast. That said, I’d be surprised if there was a significant difference between your finished product and my finished product, all else being equal.
     
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  3. Nosybear

    Nosybear Well-Known Member

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    Shouldn't be a problem - overpitch isn't as critical as underpitch. By the way, one packet, rehydrated, would have been enough for your beer.
     
  4. Weardend

    Weardend New Member

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    Thanks. Thought I'd be ok. Just can't understand why the yeast calculator on here would suggest so much. I'll trust my instincts next time.
     
  5. J A

    J A Well-Known Member

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    Yowzer! That's a lot of yeast for a mid-gravity beer. What you have to factor in with the yeast calculator is the projected yeast count. The calculator defaults to 10 billion cells/ml and the reality is probably closer to double that. Also, the target pitch rate may be set to "Pro Brewer" rather than "manufacturer recommended" which usually works just fine. a single 11 gram packet of almost any yeast will ferment a mid-gravity ESB, though, depending on yeast strain, it's not unheard of to use a bigger count for quicker, cleaner beer.
     
  6. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    It depends on cell count of the dry yeast. Some have suggested it's about 20 billion cells per gram, which seems a little high. The manufacturers have been a lot more conservative in their estimate, @ 6-8 billion per gram, counts made with a hemocytometer suggest it's higher than that. I usually guess somewhere in middle and assume 10-12 billion cells per gram.

    Based on that count, we can estimate your pitch rate. With a 1.056 gravity, it works out to be 14 degrees plato, cell count would be roughly 330 billion into 24L. Your pitch rate was @ 1.0 million cells per ml/degree plato. This would be a slight over pitch. So, one packet would be a slight under pitch (.4 million cells /ml/degree plato) and 2 packs would be around magic number of .7 million cells/ml/degree plato.

    Slight under pitches are said to increase yeast and malt character, but need proper aeration. Over pitches are thought to dry out a beer, reduce yeast and malt character. I sometimes under pitch and with lagers I always overpitch.
     
  7. Weardend

    Weardend New Member

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    Ah!
    That explains where I've been going wrong with the calculator. Thanks I was going through so much yeast and costing me a small fortune
     
  8. J A

    J A Well-Known Member

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    If you want a big pitch - and it does a good job of fast fermentation - pitch the normal amount on a low-gravity beer, rack off after it's fermented and go right back on top of it with a higher-gravity wort. It's like a massive starter. :)
     
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  9. Mark D Pirate

    Mark D Pirate Well-Known Member

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    Last time I used 3 packets of dry yeast was in a 1.15 RIS and it was messy ! Overpitching to that extent will result in very little cell growth and generally a blander beer but also lead to production of higher alcohols.

    Pitching rate is only part of the equation that also includes cell vitality , available O² , nutrient levels , wort gravity and ferment temp .

    I keep strains over generations so get to know each of them and adapt my processes to highlight or remove certain attributes when dealing with a specific strain , now I know microbiologists who propagate yeast at a commercial level the learning curve is actually getting steeper but I get the bonus of having my cultures under a microscope for definite cell counts and health
     
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  10. Hawkbox

    Hawkbox Well-Known Member

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    NNNEEERRRRDDDD!!!!
     
  11. Mark D Pirate

    Mark D Pirate Well-Known Member

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    Meh ...been called worse by better men my son
     

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