Whole yeast cake or half?

Discussion in 'Grain, Hops, Yeast & Water' started by matt76, Nov 12, 2019.

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  1. Nov 12, 2019 #1

    matt76

    matt76

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    I've done a couple of brews recently where I've dumped fresh wort onto the yeast cake from a batch I've just bottled.

    (This was two different yeast cakes, not reusing the same one several times)

    So far no issues that I'm aware of...

    But I'm sure I read, or heard something on a podcast, recently suggesting that it's ok to reuse a yeast cake but you should only use half the yeast cake.

    The reasoning is you've got old and dead yeast cells in there - by using less yeast cake I guess you've still got plenty of viable cells in there but by starting with fewer cells you're encouraging them to grow and multiply.

    (On that basis I'd have thought even a third or even a quarter yeast cake could be plenty to start with, depending a bit on ale Vs. lager yeast, your OG etc.)

    Anyone got any thoughts on this?
     
  2. Nov 12, 2019 #2

    samale

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    I regularly reuse the full yeast cake. It's a massive over pitch but I have never had a problem. I think the most I have did this is 3 times. It saves me the hassle of cleaning the fermentor.
     
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  3. Nov 12, 2019 #3

    Rodcx500z

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  4. Nov 12, 2019 #4

    samale

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    Yes no problem as long as it's a similar brew. I brew alot of American style IPA/pale ales. The only risk if the first brew is anyway infected the second brew will be on the yeast cake before you pick it up after tasting the first.
     
  5. Nov 12, 2019 #5

    Rodcx500z

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    Cheers Samale will give that a go, my mother in law keeps buying me kits from wilko when she goes in athumb.. i do ag normally acheers.
     
  6. Nov 12, 2019 #6

    Clint

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    Ah.. mother in laws....you never know to despise them or just not like them very much..
     
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  7. Nov 12, 2019 #7

    Drunkula

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    Thank god you didn't just put "Thoughts" I always ignore those threads even if I know what they're after. Like that I am.

    Well on the Brewstrong podcasts a few times they've said that yeast create certain flavours in the reproduction phase and if you put in so much yeast that they don't need to reproduce then you won't get that element. I think you've really got to know your yeast characteristics for that, which is above my pay grade.
     
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  8. Nov 12, 2019 #8

    Rodcx500z

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    I have to admit Clint I love mine she is 85 years young, makes a hell of a difference if you get on with your in laws
     
  9. Nov 12, 2019 #9

    Clint

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    I've tried....
     
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  10. Nov 12, 2019 #10

    PhilBrew

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    Hi Matt

    +1 to what Drunkula says ... and while the quantities of yeast you'll be dropping your wort onto will probably constitute a "very high pitch", rather than "over-pitching", technically ... you probably are increasing the risks of all the problems that arise from yeast not reproducing (as much), resulting in an aging population in your yeast colony, which may lead to stalled ferments/greater risk of infections/etc. :?:

    I don't know about other yeast calculators ... but the Mr. Malty calculator (link) includes an option for "Repitching from Slurry" (which is what you're yeast cake is) ... if you leave the Yeast Concentration and Non-Yeast Percentage options at the defaults ... and specify what volume of wort and at what gravity you're pitching into ... and it'll give you the volume of slurry you should use ... you'll probably find it would be around a 10th-15th of the whole cake :?:

    Cheers, PhilB
     
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  11. Nov 12, 2019 #11

    Clint

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    I've put a brew straight on top of another yeast cake and scooped out a cup full of slurry...both worked.
     
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  12. Nov 12, 2019 #12

    samale

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    I have done both with no difference between them. I brew a lot of pale ales or IPA so it's a clean fermentation. Normally S05 or CML. Not sure on the effects when your looking for the yeast to contribute certain qualities. I know the kviek yeast likes to be stressed from under pitching
     
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  13. Nov 12, 2019 #13

    matt76

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    Well I'm not at a point where I want to manipulate yeast qualities, certainly not in this way.

    I think it's just a case of considering the options to try and stack the deck as favourably for me as possible to ensure a good/healthy fermentation.

    Thanks all for your inputs athumb..
     

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