When to take your starter off the stir plate?

Discussion in 'General Brewing Discussions' started by Finn B, Jul 21, 2019.

  1. Finn B

    Finn B Member

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    In the latest edition of How to Brew, Palmer tells you to use the stir plate for only the first half of total propagation time (Notes on using a stir plate, p.122). The reason is that the yeast needs some time without oxygen in order to build up it's glycogen and trehalose reserves, which it needs during the lag phase. This also fits with what the guys from Imperial Yeast say in this Beersmith podcast: http://beersmith.com/blog/2017/12/10/imperial-yeast-and-starters-with-owen-lingley-jess-caudill-beersmith-podcast-161/ ,namely that it is detrimental to the yeast if you go on supplying oxygen after the fermentable sugars are consumed.

    So I do not doubt that this is good advice. It means that if you leave your starter spinning on your stir plate till all the sugar is consumed, you''ll get yeast with depleted energy reserves. That's to be avoided, og course.

    But I'm not happy about the way the advice is given. It's rather hard to know beforehand what the total propagation time will be. I asked Palmer, and he answered that maybe max 12 hours would be a better way to formulate it, but actually that doesn't help much either.

    This involves, I think, knowledge about what actually goes on in a starter on a stir plate, and that's not easy to come by. I have some ideas, but nothing I could call sureness. So I'd be very happy if anyone has a link to some good information about that. But what I really, from a practical point of view, need, is a figure: At what SG value should I discontinue the spinning?
     
  2. Hogarthe

    Hogarthe Well-Known Member

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    If you are measuring gravity I'd just halve the original gravity. If you started at 1.040 stop the stirplate at 1.020.... But I have no science for that. I've always just let it spin until done. Of course I did this since before I ever saw anything written that suggested not to do this.
     
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  3. Finn B

    Finn B Member

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    That may be close enough - but I really want the science:).

    I really don't like to risk infection by taking samples, but I'll do it until I've learned to recognize the correct level visually. Hopefully I can do that.
     
  4. Nosybear

    Nosybear Well-Known Member

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    Given our cell counts are at best an estimate and at worst a guess, I won't lose sleep over a few billion cells one way or the other. As long as it's close, you'll get good beer. If you want to do the science, you need a microscope, a hemocytometer and a pipette. John is an engineer, he wants exact numbers. Homebrewing exists in the intersection between engineering and art. Close enough often works well. Last month stir plates were passe, this month use them but turn them off halfway through.... Find a process that works and stick with it, you'll brew better beer that way.
     
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  5. Trialben

    Trialben Well-Known Member

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    I know Braukiser has done a scientific style experiment of stir plate speeds and cell growth. Might be worth a look on his site by same name.
     
  6. Finn B

    Finn B Member

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    You didn't understand my question. I'm not concerned about cell count, but about the quality of the yeast I get, and I want to base what I do on as solid knowledge as I can get.

    And my trouble with Palmer's advice is that he doesn't give me the numbers I want:).
     
  7. Finn B

    Finn B Member

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    Oh, I know that one well. But again, it's not cell count/growth rates I'm asking about.

    I'm new on this forum, but I'm not a novice brewer:p.
     
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  8. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    I understand what your asking, will I have better yeast if the yeast finishes and sets a period without oxygen. It’s fairy well understood that yeast in a dormant state fair better without oxygen.

    They may pick up more reserves of key nutrients, but does it make the beer better? There are people out there that swear stir plates cause “shear” in yeast cells. This is partly true, but the stir plate would have to at centrifuge RPM’s for this to occur. So some have sworn off stir plates and gone to a shaken not stirred method.

    If you want to try this method, I would stir for about 12 hours, most of the sugars will be consumed by that time. Leave it set still for 12 hours and either pitch it into wort or cool for a later use.

    I personally don’t believe there is much oxygen getting to the yeast in the first 24 hours because of cO2 production, but it wouldn’t hurt to try the 12/12 method. If the yeast is left on a stir plate for more than 24 hours, that could be bad.

    Yeast can be pretty resilient and if the reserves are a little short, the oxygen level at pitch are crucial. That may be why people are getting away with spinning straight through for 24 hours, they aerate the wort well. There many, many ways to skin a cat. Try it see if it makes a difference.
     
  9. Trialben

    Trialben Well-Known Member

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    Man I just wack em on the stir plate and walk away but good luck to you if you want to come back in 12 hours and switch it off heck you could put it on a timer to do this too.

    I've always just left it spin untill after krausen then when I see it dropping I'll turn it off take my next gen sample and let it all settle.
     
  10. Nosybear

    Nosybear Well-Known Member

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    I'm with you. Mix up the starter, get it on the plate and let it spin. When I think it's done, I switch it off and let the yeast settle, pour off the beer and use the yeast. I'm probably sacrificing a few billion cells doing it that way but it's close enough for my beers.
     
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  11. Ozarks Mountain Brew

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    I'm similar, I use the stir plate until it stops foaming, turn it off then add the flask to a sealed 2 gallon baggie, add that to the keezer set at 34F, it solidifies then I pour off almost all the beer completely
     
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  12. Finn B

    Finn B Member

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    #12 Finn B, Jul 22, 2019
    Last edited: Jul 22, 2019
    If you didn't continously supply the yeast with some oxygen through stirring, intermittent shaking would be more efiicient. And I think Braukaiser shoved that vigorous stirring on a plate without capping is the most efficient way. You get less yeast growth if you use an airlock.

    Shearing of the yeast is a myth. As you say, you would have to spin the magnet much faster than we do in order to damage the yeast.

    I'm not sure the oxygen will help you much if the energy reserves of the yeast are depleted, which is what is happening if you spin for too long. (But I've earned my living teaching litterature, history and philosophy, not real science, sadly. So my knowledge about these matters aren't too deep. I've tried to understand a little, though:).)

    I'm sorry, guys; it's nice to know what you're doing, but what I wanted was some solid science based information about when to take the starter off the stir plate. I haven't been able to find any, and I'm at a loss to understand why all those people out there haven't cried out for this in unison:). I can't be the only one who have felt the need for something a little more solid to base my actions on?
     
  13. Mase

    Mase Well-Known Member

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    Dry, liquid, older, starter, no starter, underpiched or overpitched, I’ve not had a dumper yet due to the yeast (knock on wood). Good luck on your quest, but until I find a need, I’m not chasing ghosts.
     
  14. Ozarks Mountain Brew

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    this may not answer your question about a stir plate but good info on how and when yeast will use the oxygen from the owner of white labs

     
  15. Finn B

    Finn B Member

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    #15 Finn B, Jul 22, 2019
    Last edited: Jul 22, 2019
    Why do you say that? It's not a ghost, it's information I assume someone must be able to supply.

    "Best practice" isn't necessarily necessary. Most of the time you won't notice any difference if you chose to neglect just one such point. But I'm fairly convinced that you get a better beer if you care about all those details. It's the sum of them that makes a difference.

    And I've tasted plenty of pretty bad homebrew that the the brewer claimed was good stuff, so I'm not much inclined to listen to advice based on what people have found out works for them. I'm not very much inclined to trust my own experience, either:). (But at least I know what my own beer tastes like;).)
     
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  16. Finn B

    Finn B Member

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    Thanks, but that deals with ordinary fermentations. What goes on in a starter where you continously supply oxygen isn't quite the same. So yeah, you're right; it doesn't answer my question:(.
     
  17. Mase

    Mase Well-Known Member

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    #17 Mase, Jul 22, 2019
    Last edited: Jul 22, 2019
    Oh trust me... I’ve been down my share of rabbit holes, but when it comes to living organisms [yeast] there’s a certain amount of variability that needs to be considered, and trying to get the decimal point any further one way or the other would be similar to chasing a ghost [it keeps moving out of reach or changing directions]. I’ve enjoyed and learned from this thread and followup comments, so its time for me to RDWHAHB....
     
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  18. Finn B

    Finn B Member

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    I did some editing of my first answer, you may consider that part of this post, too.

    I may elaborate a little on what I'm after.

    Yeast cells are individuals, that's right. They don't all do the same at the same time, and different yeast strains are also different. So I'm not actually chasing a specific number - though I guess I actually asked for one - but rather a zone. But one would have to use SG values to describe it, I think.

    The Crabtree effect (mostly) keeps the yeast from respiring even if it has access to oxygen. But when the level of fermentable sugar gets too low, that effect stops working. The yeast may then, after the sugar is consumed, go on respiring ethanol to get energy, and it won't start the hibernation process. Or rather, this is what I assume happen, and what I assume must be the reason why you should stop supplying oxygen.

    What I'm after, then, is the point where the Crabtree effect is negated. This of course assuming that what I say here is right - and I'm not at all certain. It's just damned hard to find information about this that is accessible - and can be understood by someone who has no basic chemistry/biochemistry knowledge.

    So the ghost I'm chasing is a scientist with a deep understanding of these processes, and the ablity to explain what's going on in there to a layman:). (In my experience the test of a persons knowledge is his or her ability to make a layman understand.)
     
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  19. Hawkbox

    Hawkbox Well-Known Member

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    I leave it on the stir plate until I remember that I forgot to take it off, then I go grab it and pour it into the wort. Plus keep some in a jar for next time.
     
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  20. HighVoltageMan!

    HighVoltageMan! Well-Known Member

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    #20 HighVoltageMan!, Jul 22, 2019
    Last edited: Jul 22, 2019
    I think your search for answers and your quest for better beer is admirable. Some of the best advice I heard was never take advice from someone unless you taste their beer or if they are known to a great brewer (I guess that includes my advice).

    In the past I did quite a bit research on yeast and to find the answer to one question required me to go to multiple sources, most often I found the answer in some obscure white paper I found after hours of looking. I rarely found real specific information on forums, but I did find leads. People on forums may mean well, but often give misinformed answers that mislead or discount your idea.

    You may find an answer somewhere, but measuring an outcome or significant improvement in the beer may prove frustrating. However, often great beer comes from an accumulation of small changes. If one of the changes were removed it would make little difference, but the sum of all the improvements/changes makes a world of difference.

    I am a believer in yeast being the key to great beer, any improvement is usually worth the effort. I wish you luck. But it may be that Palmer is blowing smoke up people’s asses or he’s on to something. Who knows? Time will tell.
     
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