Author Topic: 2 stage yeast starter  (Read 8112 times)

Big Monk

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Re: 2 stage yeast starter
« Reply #15 on: January 15, 2017, 07:09:58 PM »
I wonder about staged starters when people are pitching 100ml to 1L, decanting and adding another 1L. At some point it seems the growth will not be what some expect because the yeast amount will be getting close to max for the volume anyway.

That's a good point that is probably often missed.  I believe the max is 200B per liter.  If you've already got 200B cells, you aren't going to grow more by decanting them into another liter of wort - yet another thing I learned from S.C.


Offline SilverZero

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Re: 2 stage yeast starter
« Reply #16 on: January 23, 2017, 12:23:16 AM »
This is my first post, I just registered after reading about 50 pages of yeast starter threads because I wanted to join the conversation. It seems Mark is gone now?

When propagating a starter, do we assume a well-oxygenated (dare I say SNS) starter will always reach maximum cell density of 200b cells/L if the inoculation  rate is reasonable?

I've got a 100-day-old pack of 1764 that I'm going to start with 2L of 1.040 wort for an 11 gallon CDA (two 1-L starters each with half a pack of yeast). Assuming a high-end estimate of 20% loss of viability per month, I figure I can reasonably expect 50b live cells total, or 25b per starter jar. Is it safe to also expect that I'll reach that max cell density of 200b cells in each starter after 3 doubling times of 90 minutes, plus a little while to get rolling after inoculation?
« Last Edit: January 23, 2017, 12:26:11 AM by SilverZero »

Offline klickitat jim

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Re: 2 stage yeast starter
« Reply #17 on: January 23, 2017, 12:26:35 AM »
Maybe... too many variables to say for sure. How high is the gravity of your CDA?

Offline SilverZero

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Re: 2 stage yeast starter
« Reply #18 on: January 23, 2017, 12:44:26 AM »
Maybe... too many variables to say for sure. How high is the gravity of your CDA?

The CDA is 1.064, but I'm asking about the starter yeast population. In all the reading I did this weekend, everybody (mainly Mark) only refers to max cell density, but I never could tell if that was a given. It seems it should be, if nothing is limiting the yeast growth.

In other words, when we plan yeast starters, do we plan assuming every liter at (or beyond) HK will contain 200b cells? I am pretty sure that's how most of us understand it, and it makes starter calculations a lot simpler in my mind.

Offline klickitat jim

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Re: 2 stage yeast starter
« Reply #19 on: January 23, 2017, 01:36:37 AM »
Frankly, since learning from Mark, I don't care about yeast cell counts anymore. For 6 gallons of 1.065 ale or lager  I build one 1L oxygenated starter morning of brew day, I give ale starters 8 hrs to hit exponential phase, and lagers 12 hrs. Then I pitch the whole thing. The thinking being that at exponential phase you are only ~90 minutes from doubling. So the difference between 200 billion and 400 billion is 90 minutes. My beers always show airlock activity by the next day

Offline SilverZero

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Re: 2 stage yeast starter
« Reply #20 on: January 23, 2017, 01:53:59 AM »
Thanks, that's essentially the mindset I've adopted as well.

Offline klickitat jim

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Re: 2 stage yeast starter
« Reply #21 on: January 23, 2017, 01:59:51 AM »
The main reason to pitch X amount of cells is to ensure domination against any contamination. So we are wise pitching X amount. If your yeast isn't dormant and doesn't have to go through lag, then less than X is required. I know what works for me and if I did a 10 gallon batch I might just do 1L with one smack pack, or if that made me nervous I'd do two

The Beerery

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2 stage yeast starter
« Reply #22 on: January 23, 2017, 02:01:28 AM »
My only curveball to this is that In Low oxygen brewing is that you will have flavor degradation due to oxidation if you don't have activity in 6-8hrs.
 

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Offline klickitat jim

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Re: 2 stage yeast starter
« Reply #23 on: January 23, 2017, 02:11:03 AM »
There's yeast activity way before there is airlock activity

Offline SilverZero

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Re: 2 stage yeast starter
« Reply #24 on: January 23, 2017, 02:11:57 AM »
My only curveball to this is that In Low oxygen brewing is that you will have flavor degradation due to oxidation if you don't have activity in 6-8hrs.
 

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Okay, so what constitutes "activity"? If I pitch any number of cells at HK, there's going to be activity whether I can see it or not, right?

Are you saying you're arguing for a higher pitch rate so the colony will take up the oxygen faster? I'd still want to know how fast X cells can deplete Y ppm of O2.

I realize this is a can of worms and I'm probably hijacking, so we can take this to a new thread if necessary.
« Last Edit: January 23, 2017, 02:15:38 AM by SilverZero »

Offline klickitat jim

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Re: 2 stage yeast starter
« Reply #25 on: January 23, 2017, 02:15:23 AM »
My only curveball to this is that In Low oxygen brewing is that you will have flavor degradation due to oxidation if you don't have activity in 6-8hrs.
 

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Okay, so what constitutes "activity"? If I pitch any number of cells at HK, there's going to be activity whether I can see it or not, right?
In my understanding, if your pitch is active, it's active the moment you pitch it. If you pitch dormant cells, who knows how long.

The Beerery

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Re: 2 stage yeast starter
« Reply #26 on: January 23, 2017, 02:16:25 AM »
Sure it's all about taking that wort DO to zero.


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Offline klickitat jim

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Re: 2 stage yeast starter
« Reply #27 on: January 23, 2017, 02:28:06 AM »
I don't have a DO meter. I assume the greatest oxidation issue is building the starter. Based on your experience...

Say I smack the pack and it has begun to expand. I open my canned starter wort, pour to my flask, immediately pitch and oxygenate. It sits with a foil lid for 8 hrs. I pitch the starter to my beer and oxygenate. In your experience would that create detectable oxidation in the final product?

Offline a10t2

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Re: 2 stage yeast starter
« Reply #28 on: January 23, 2017, 02:28:12 AM »
When propagating a starter, do we assume a well-oxygenated (dare I say SNS) starter will always reach maximum cell density of 200b cells/L if the inoculation  rate is reasonable?

My starters tend to run around 120-150 billion cells per liter.
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Offline SilverZero

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Re: 2 stage yeast starter
« Reply #29 on: January 23, 2017, 02:36:45 AM »
When propagating a starter, do we assume a well-oxygenated (dare I say SNS) starter will always reach maximum cell density of 200b cells/L if the inoculation  rate is reasonable?

My starters tend to run around 120-150 billion cells per liter.

Ah, interesting! Thanks!