Author Topic: Yeast Generation Count from a Starter  (Read 2383 times)

Offline thebigbaker

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Yeast Generation Count from a Starter
« on: October 29, 2014, 02:30:47 AM »
So I've been busy this year and haven't brewed at all most of the year and started back up brewing in September.  I'm now back to brewing 3-4 times a month and it's good to be back on the horse!

Anyways, I've been making my starters 500ml larger than what is required and saving that extra 500ml.  For the next brew I take that extra 500ml and make another starter which is 500ml larger and save that extra 500ml for a starter for the following brew.

My question is, with each new starter I do, is that considered a new generation of yeast?  If so, about how many generations (or cycles?) can I do this, considering my sanitation is good?

So far, I've done this for 5 brews and so far no issues (I've got a 6th brew fermenting and haven't tried it yet).  Basically my process is after the starter is complete, I take it right off the stir plate and fill up a sanitized mason jar (which is about 500ml) and put the mason jar in the fridge.  When it's time to make a new starter for the next brew, I just decant, swirl around and pitch into the starter wort. 

I brew 3-4 times a month so it doesn't stay in the fridge more than 2 weeks before going into the next starter.

Thanks in advance for any input and/or advice!
Jeremy Baker

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Offline Wort-H.O.G.

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Re: Yeast Generation Count from a Starter
« Reply #1 on: October 29, 2014, 10:52:14 AM »
So I've been busy this year and haven't brewed at all most of the year and started back up brewing in September.  I'm now back to brewing 3-4 times a month and it's good to be back on the horse!

Anyways, I've been making my starters 500ml larger than what is required and saving that extra 500ml.  For the next brew I take that extra 500ml and make another starter which is 500ml larger and save that extra 500ml for a starter for the following brew.

My question is, with each new starter I do, is that considered a new generation of yeast?  If so, about how many generations (or cycles?) can I do this, considering my sanitation is good?

So far, I've done this for 5 brews and so far no issues (I've got a 6th brew fermenting and haven't tried it yet).  Basically my process is after the starter is complete, I take it right off the stir plate and fill up a sanitized mason jar (which is about 500ml) and put the mason jar in the fridge.  When it's time to make a new starter for the next brew, I just decant, swirl around and pitch into the starter wort. 

I brew 3-4 times a month so it doesn't stay in the fridge more than 2 weeks before going into the next starter.

Thanks in advance for any input and/or advice!

one question- the extra 500ml seems to refer to the wort volume and not the yeast volume. how much yeast are you harvesting from each 500mL larger starter? 60ml of slurry or 1/4 cup?
Ken- Chagrin Falls, OH
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Offline majorvices

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Re: Yeast Generation Count from a Starter
« Reply #2 on: October 29, 2014, 01:33:54 PM »
Depends on how you make your starter. If you keep them in the respiratory stage then it does not count as a gen. If you make a simple, unstirred/unaerated starter then that counts as one gen.

Least, that's how I understand it.

Offline thebigbaker

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Re: Yeast Generation Count from a Starter
« Reply #3 on: October 29, 2014, 02:16:01 PM »
[quote author=wort-h.o.g. link=topic=20901.msg264866#msg264866 date=1414579934

one question- the extra 500ml seems to refer to the wort volume and not the yeast volume. how much yeast are you harvesting from each 500mL larger starter? 60ml of slurry or 1/4 cup?
[/quote]

Yes, the extra 500ml is total volume (yeast + wort).  I basically take my starter (which is from 1056) turn off the stir plate after it looks finished (about 24 hrs), immediately pour 1L into another sanitized flask (which I chill/ decant and use for the current brew) and take the rest and pour into a mason jar and save for the next starter/ brew (fills the pint mason jar to the top and usually have just a little extra, about 5-10ml extra).  I have about 45 - 50ml of slurry in the mason jar from the left over 500ml of the 1.5L starter.

As a side note, most of my beers are 3 gallon batches and the beers I've been using this process for are all above 1.070 w/ most being 1.084+.  When it gets cold, I crave the big beers!

Jeremy Baker

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Offline thebigbaker

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Re: Yeast Generation Count from a Starter
« Reply #4 on: October 29, 2014, 02:18:09 PM »
Depends on how you make your starter. If you keep them in the respiratory stage then it does not count as a gen. If you make a simple, unstirred/unaerated starter then that counts as one gen.

Least, that's how I understand it.

Thanks Keith, as mentioned above, I keep the stir plate going right up until I split the starter up (1L and 500ml).  Not exactly sure what respiratory stage is, so I'll have to ask that google thing.
Jeremy Baker

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Re: Yeast Generation Count from a Starter
« Reply #5 on: October 29, 2014, 02:27:07 PM »
Depends on how you make your starter. If you keep them in the respiratory stage then it does not count as a gen. If you make a simple, unstirred/unaerated starter then that counts as one gen.

Least, that's how I understand it.

Thanks Keith, as mentioned above, I keep the stir plate going right up until I split the starter up (1L and 500ml).  Not exactly sure what respiratory stage is, so I'll have to ask that google thing.

seems like you have a good process thats working for ya, so keep doing what works. I am interested to see what is said about the generation question.
Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

http://braukaiser.com/wiki/index.php?title=The_Science_of_Mashing

Serving:        In Process:
Vienna IPA          O'Fest
Dort
Mead                 
Cider                         
Ger'merican Blonde
Amber Ale
Next:
Ger Pils
O'Fest

Offline morticaixavier

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Re: Yeast Generation Count from a Starter
« Reply #6 on: October 29, 2014, 02:33:30 PM »
with a little tweak you could at least reduce the number of generations you're going through.

If you start a cycle by making one large starter, say 2000ml and split that 4 ways when it's done then you get 3 pitches from each generation with the 4th being the starter for the next generation.
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Offline thebigbaker

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Re: Yeast Generation Count from a Starter
« Reply #7 on: October 29, 2014, 03:18:13 PM »
with a little tweak you could at least reduce the number of generations you're going through.

If you start a cycle by making one large starter, say 2000ml and split that 4 ways when it's done then you get 3 pitches from each generation with the 4th being the starter for the next generation.

Thanks and that's a great idea and I'll definitely try that!
Jeremy Baker

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Re: Yeast Generation Count from a Starter
« Reply #8 on: October 29, 2014, 06:01:55 PM »
as long as the wort gravity is low and there is constant aeration the yeast won't be making alcohol and mutation should be negligent so there should be no reason to add a generation.

Offline denny

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Re: Yeast Generation Count from a Starter
« Reply #9 on: October 29, 2014, 06:39:00 PM »
as long as the wort gravity is low and there is constant aeration the yeast won't be making alcohol and mutation should be negligent so there should be no reason to add a generation.

Don't forget the Crabtree Effect...in the presence of a >.05% glucose solution, fermentation will take place.  Even with aeration.
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Offline thebigbaker

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Re: Yeast Generation Count from a Starter
« Reply #10 on: October 29, 2014, 07:20:38 PM »
as long as the wort gravity is low and there is constant aeration the yeast won't be making alcohol and mutation should be negligent so there should be no reason to add a generation.

Don't forget the Crabtree Effect...in the presence of a >.05% glucose solution, fermentation will take place.  Even with aeration.

Crabtree Effect...I'm giving that google a workout today!
Jeremy Baker

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Re: Yeast Generation Count from a Starter
« Reply #11 on: October 29, 2014, 07:25:31 PM »

as long as the wort gravity is low and there is constant aeration the yeast won't be making alcohol and mutation should be negligent so there should be no reason to add a generation.

Don't forget the Crabtree Effect...in the presence of a >.05% glucose solution, fermentation will take place.  Even with aeration.

Still very minimal though.

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Re: Yeast Generation Count from a Starter
« Reply #12 on: October 29, 2014, 07:32:12 PM »

as long as the wort gravity is low and there is constant aeration the yeast won't be making alcohol and mutation should be negligent so there should be no reason to add a generation.

Don't forget the Crabtree Effect...in the presence of a >.05% glucose solution, fermentation will take place.  Even with aeration.

Still very minimal though.

so "as long as the gravity is low" and "wont be making alcohol"....not sure i get that. low OG still makes alcohol, no? how low we talking about.
Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

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Dort
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Offline narcout

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Re: Yeast Generation Count from a Starter
« Reply #13 on: October 29, 2014, 07:59:51 PM »
so "as long as the gravity is low" and "wont be making alcohol"....not sure i get that. low OG still makes alcohol, no? how low we talking about.

Brewing yeast can both respire (requires presence of fee oxygen) and ferment (which does not).  However, even in the presence of oxygen, yeast will ferment rather than respire if there is sufficient glucose present (the Crabtree effect).

I've seen different figures listed for the glucose threshold, including 0.3%, 0.4% and 0.5% w/v.   
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Re: Yeast Generation Count from a Starter
« Reply #14 on: October 29, 2014, 08:55:27 PM »
so "as long as the gravity is low" and "wont be making alcohol"....not sure i get that. low OG still makes alcohol, no? how low we talking about.

Brewing yeast can both respire (requires presence of fee oxygen) and ferment (which does not).  However, even in the presence of oxygen, yeast will ferment rather than respire if there is sufficient glucose present (the Crabtree effect).

I've seen different figures listed for the glucose threshold, including 0.3%, 0.4% and 0.5% w/v.   

ok makes sense. so how do you make a starter that builds new yeast without glucose?
Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

http://braukaiser.com/wiki/index.php?title=The_Science_of_Mashing

Serving:        In Process:
Vienna IPA          O'Fest
Dort
Mead                 
Cider                         
Ger'merican Blonde
Amber Ale
Next:
Ger Pils
O'Fest