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Date: 09 Jun 2006 10:06:48
From: Washu
Subject: Limiting yeast replications
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I've been reading that traditional scotch ales held their yeast
to 3 replications instead of the typical 5 (nods head knowingly)
but frankly I don't have a clue how to go about it except by
pitching a starter big enough to bring a 1.080 wort to completion
in 3 cycles. My question is how big of a starter I would need
to bring a 5 US gallon batch to completion in this window?
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Date: 09 Jun 2006 21:12:33
From: HAL 9000
Subject: Re: Limiting yeast replications
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"Washu" <rgrantha@yahoo.com > wrote in message
news:1149872808.377710.296710@f6g2000cwb.googlegroups.com...
> I've been reading that traditional scotch ales held their yeast
> to 3 replications instead of the typical 5 (nods head knowingly)
> but frankly I don't have a clue how to go about it except by
> pitching a starter big enough to bring a 1.080 wort to completion
> in 3 cycles. My question is how big of a starter I would need
> to bring a 5 US gallon batch to completion in this window?
>
Isn't attenuation the ultimate concern rather than how the attenuation is
achieved in terms of # of yeast generations?
I guess my question is, how do replications relate to attenuation? Or is
there a relationship? I suppose that's essentially your question as well.
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Date: 09 Jun 2006 12:18:56
From: Denny Conn
Subject: Re: Limiting yeast replications
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Washu wrote:
> According to Ray Daniels the growth of yeast is restricted to a
> threefold growth, far as I can figure it has something to do with
> eliminating fermentation by-products from the slow (3 weeks)
> cool (55F) primary. Maybe that enviroment would cause the yeast
> to start making off-flavors? Just guessing.
>
> FWIW I knew you'd be the first to reply. I appreciate not only
> your knowledge, but even more your generosity in sharing it.
I was talking to Dave Logsdon, from Wyeast, about this recently. He
said that yeast naturally will do about 3 reprductive cycles ("budding"
he called it). I think it's pretty much a self limiting thing.
---------- >Denny
--
Life begins at 60...1.060, that is.
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Date: 09 Jun 2006 17:59:08
From: JS
Subject: Re: Limiting yeast replications
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On Fri, 09 Jun 2006 12:18:56 -0700, Denny Conn
<denny.g.conn@ci.eugene.or.us > wrote:
>Washu wrote:
>
>> According to Ray Daniels the growth of yeast is restricted to a
>> threefold growth, far as I can figure it has something to do with
>> eliminating fermentation by-products from the slow (3 weeks)
>> cool (55F) primary. Maybe that enviroment would cause the yeast
>> to start making off-flavors? Just guessing.
>>
>> FWIW I knew you'd be the first to reply. I appreciate not only
>> your knowledge, but even more your generosity in sharing it.
>
>I was talking to Dave Logsdon, from Wyeast, about this recently. He
>said that yeast naturally will do about 3 reprductive cycles ("budding"
>he called it). I think it's pretty much a self limiting thing.
>
> ---------->Denny
What I've never understood about this is how, after the 3 repro
cycles, one could then repitch all or a portion of this and get good
results. I mean, I've done it many times, as have others. Something
I'm not grasping here. If the yeast is spent after 3 cycles, how do
they start the process all over again when going into fresh wort?
John S.
--
Posted via NewsDemon.com - Premium Uncensored Newsgroup Service
------- >>>>>>http://www.NewsDemon.com<<<<<<------
Unlimited Access, Anonymous Accounts, Uncensored Broadband Access
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Date: 10 Jun 2006 09:28:22
From: rb
Subject: Re: Limiting yeast replications
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JS wrote:
[snip]---------- >Denny
>
> What I've never understood about this is how, after the 3 repro
> cycles, one could then repitch all or a portion of this and get good
> results. I mean, I've done it many times, as have others. Something
> I'm not grasping here. If the yeast is spent after 3 cycles, how do
> they start the process all over again when going into fresh wort?
>
> John S.
[snip]
I'm guessing here, but I would presume that after the third cycle, all
the oxygen would be gone, as would most of the nutrients required for
reproduction (having been used up by the yeast in the three cycles).
It's only after you add these yeast to a fresh batch of wort containing
oxygen and nutrients (FANs etc) that they are able to start reproducing
again.
As I understand it, the term 'spent yeast' or even 'burnt out yeast' is
more a reference to depleted yeast. Like after running a marathon the
runner can be spent or burnt out, but given a few days to recover
(rehydrate etc) is good to go again.
rb
--
Posted via a free Usenet account from http://www.teranews.com
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Date: 12 Jun 2006 16:50:51
From: John 'Shaggy' Kolesar
Subject: Re: Limiting yeast replications
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On Fri, 09 Jun 2006 17:59:08 -0400, < > wrote:
> What I've never understood about this is how, after the 3 repro
> cycles, one could then repitch all or a portion of this and get good
> results. I mean, I've done it many times, as have others. Something
> I'm not grasping here. If the yeast is spent after 3 cycles, how do
> they start the process all over again when going into fresh wort?
When you repitch a large population of yeast from a previous batch, they
have to do a lot less reproducing.
John.
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Date: 09 Jun 2006 12:07:29
From: Washu
Subject: Re: Limiting yeast replications
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> What do you mean by replications? Do you really mean that they
> limited the yeast to only 3 reproductions, aka 3 generations, or
> do you mean that they only reused the same yeast for 3 different beers?
I mean 3 generations, IE brand new yeast
> If you are talking about forcing your yeast to only go through 3
> reproductions... why? Yes, pitching larger amounts up front will help
> (up to a point where you are over pitching), but what is magic about
> 3 generations versus 5 generations?
According to Ray Daniels the growth of yeast is restricted to a
threefold growth, far as I can figure it has something to do with
eliminating fermentation by-products from the slow (3 weeks)
cool (55F) primary. Maybe that enviroment would cause the yeast
to start making off-flavors? Just guessing.
FWIW I knew you'd be the first to reply. I appreciate not only
your knowledge, but even more your generosity in sharing it.
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Date: 09 Jun 2006 19:14:19
From: John 'Shaggy' Kolesar
Subject: Re: Limiting yeast replications
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On 9 Jun 2006 12:07:29 -0700, <rgrantha@yahoo.com > wrote:
> According to Ray Daniels the growth of yeast is restricted to a
> threefold growth, far as I can figure it has something to do with
> eliminating fermentation by-products from the slow (3 weeks)
> cool (55F) primary. Maybe that enviroment would cause the yeast
> to start making off-flavors? Just guessing.
Hmm, I'm not familiar with that. I'll have to go back and read
my Daniels book again.
John.
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Date: 09 Jun 2006 17:43:33
From: John 'Shaggy' Kolesar
Subject: Re: Limiting yeast replications
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On 9 Jun 2006 10:06:48 -0700, <rgrantha@yahoo.com > wrote:
> I've been reading that traditional scotch ales held their yeast
> to 3 replications instead of the typical 5 (nods head knowingly)
What do you mean by replications? Do you really mean that they
limited the yeast to only 3 reproductions, aka 3 generations, or
do you mean that they only reused the same yeast for 3 different beers?
If you are talking about forcing your yeast to only go through 3
reproductions... why? Yes, pitching larger amounts up front will help
(up to a point where you are over pitching), but what is magic about
3 generations versus 5 generations?
John.
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Date: 12 Jun 2006 11:32:09
From: Scott L
Subject: Re: Limiting yeast replications
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JS wrote:
> What I've never understood about this is how, after the 3 repro
> cycles, one could then repitch all or a portion of this and get good
> results. I mean, I've done it many times, as have others. Something
> I'm not grasping here. If the yeast is spent after 3 cycles, how do
> they start the process all over again when going into fresh wort?
There's really no such thing as "spent" yeast. Yeast have been around
for billions of years, no? Given the right conditions, they rejuvenate
themselves and are happy to work again. It's just that it's so much
simpler to just buy some fresh yeast instead of bothering with all
that.
The problem with repeated harvesting/reuse of yeast is that unwanted
organisms (wild yeasts, mutant forms of the original yeast, bacteria,
etc.) slowly build up and begin to compete with the desired yeast.
You can acid wash, plate out from a single cell to rid yourself of
mutants, etc etc., but you kind of have to enjoy that for its own sake
in order to justify the effort when yeast is so readily available.
Scott
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