Author Topic: Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter  (Read 4585 times)

S. cerevisiae

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Re: Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter
« Reply #30 on: April 23, 2015, 02:47:25 PM »
A yeast culture is kind of like a nuclear weapon in that one only needs to be less than an order of magnitude away from a calculated yeast cell count in order for it to be effective.  Given enough carbon and oxygen, the difference in propagation time between 50 billion cells and 200 billion cells is 180 minutes at 25C.

With that said, your experiment also highlights something else I that have been championing on this forum; namely, that one should pitch at high krausen instead of waiting until the starter has fermented out.  Cells that are pitched at high krausen are in better health than those that have reached quiescence.  However, in your case, you demonstrated the difference in health between two different cultures that had reached quiescence.  One culture had recently reached quiescence whereas the other had been in a quiescent state for an extended period of time.  Yeast cell health declines as the cells get further away from high krausen. 

Here's what really made the difference in lag times.  In addition to increasing the size of the biomass, the starter gave the yeast cells time replenish reserves that had been exhausted during an extended period of quiescence.  Additionally, the starter was propagated at room temperature, which is closer to 25C than the typical fermentation temperature.  The lag time on the direct pitch would have been a fraction of the time that it was had you pitched at 21C/70F and waited for visible sighs of fermentation to appear before placing the fermentation vessel into your fermentation chamber.  Yeast metabolism slows as temperature is decreased.  Anything that slows yeast metabolism increases the the length of the replication period.  However, in this case, slowing yeast metabolism was not necessarily a bad thing because low temperatures affect wild microflora more than they do domesticated brewing yeast strains.

« Last Edit: April 24, 2015, 01:03:05 PM by S. cerevisiae »

Offline denny

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Re: Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter
« Reply #31 on: April 23, 2015, 03:17:04 PM »
I agree completely with which ever side is ultimately proven correct.

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Offline brulosopher

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Re: Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter
« Reply #32 on: April 23, 2015, 09:46:33 PM »

A yeast culture is kind of like nuclear weapons in that one only needs to be less than an order of magnitude away from a calculated yeast cell count in order for it to be effective.  Given enough carbon and oxygen, the difference in propagation time between 50B cells and 200 billion cells is 180 minutes at 25C.

With that said, your experiment also highlights something else I that have been championing on this forum; namely, that one should pitch at high krausen instead of waiting until the starter has fermented out.  Cells that are pitched at high krausen are in better health than those that have reached quiescence.  However, in your case, you demonstrated the difference in health between two different cultures that had reached quiescence.  One culture had recently reached quiescence whereas the other had been in a quiescent state for an extended period of time.  Yeast cell health declines as the cells get further away from high krausen. 

Here's what really made the difference in lag times.  In addition to increasing the size of the biomass, the starter gave the yeast cells time replenish reserves that had been exhausted during an extended period of quiescence.  Additionally, the starter was propagated at room temperature, which is closer to 25C than the typical fermentation temperature.  The lag time on the direct pitch would have been a fraction of the time that it was had you pitched at 21C/70F and waited for visible sighs of fermentation to appear before placing the fermentation vessel into your fermentation chamber.  Yeast metabolism slows as temperature is decreased.  Anything that slows yeast metabolism increases the the length of the replication period.  However, in this case, slowing yeast metabolism was not necessarily a bad thing because low temperatures affect wild microflora more than they do domesticated brewing yeast strains.

This is fantastic, thank you! Based on your name, you seem an authority on the subject. If ever you feel like contributing, shoot me an email (brulosopher@gmail.com), I'd love to have little "from the expert" snippets like this included in our results articles :)

Offline Wort-H.O.G.

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Re: Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter
« Reply #33 on: April 23, 2015, 10:20:00 PM »

A yeast culture is kind of like nuclear weapons in that one only needs to be less than an order of magnitude away from a calculated yeast cell count in order for it to be effective.  Given enough carbon and oxygen, the difference in propagation time between 50B cells and 200 billion cells is 180 minutes at 25C.

With that said, your experiment also highlights something else I that have been championing on this forum; namely, that one should pitch at high krausen instead of waiting until the starter has fermented out.  Cells that are pitched at high krausen are in better health than those that have reached quiescence.  However, in your case, you demonstrated the difference in health between two different cultures that had reached quiescence.  One culture had recently reached quiescence whereas the other had been in a quiescent state for an extended period of time.  Yeast cell health declines as the cells get further away from high krausen. 

Here's what really made the difference in lag times.  In addition to increasing the size of the biomass, the starter gave the yeast cells time replenish reserves that had been exhausted during an extended period of quiescence.  Additionally, the starter was propagated at room temperature, which is closer to 25C than the typical fermentation temperature.  The lag time on the direct pitch would have been a fraction of the time that it was had you pitched at 21C/70F and waited for visible sighs of fermentation to appear before placing the fermentation vessel into your fermentation chamber.  Yeast metabolism slows as temperature is decreased.  Anything that slows yeast metabolism increases the the length of the replication period.  However, in this case, slowing yeast metabolism was not necessarily a bad thing because low temperatures affect wild microflora more than they do domesticated brewing yeast strains.

This is fantastic, thank you! Based on your name, you seem an authority on the subject. If ever you feel like contributing, shoot me an email (brulosopher@gmail.com), I'd love to have little "from the expert" snippets like this included in our results articles :)

Yes Mark has some great knowledge and expertise with yeast. Ive tried his approach for my ales with smaller starter pitched at high krausen and cant say I find anything wrong with it. I have not done it with lagers mostly because of the volume of the starter and it worries me about pitching all that DME wort into my lager. one day perhaps I will brave it and try and see .....just haven't gotten there yet  ;D
« Last Edit: April 23, 2015, 10:30:21 PM by Wort-H.O.G. »
Ken- Chagrin Falls, OH
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Offline klickitat jim

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Re: Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter
« Reply #34 on: April 23, 2015, 10:22:30 PM »
His real name is Pedio so dont get too excited.

Offline mchrispen

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Re: Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter
« Reply #35 on: April 23, 2015, 10:26:54 PM »
Jim, you are clearly not in a quiescent state! Poor Mark! But that did make me laugh out loud.
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Offline erockrph

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Re: Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter
« Reply #36 on: April 23, 2015, 10:31:01 PM »
Yes Mark has some great knowledge and expertise with yeast. Ive tried his approach for my ales with smaller starter pitched at high krausen and cant say I find anything wrong with it. I have not done it with lagers mostly because of the volume of the starter and it worries about pitching all that DME wort into my lager. one day perhaps I will brave it and try and see .....just haven't gotten there yet  ;D
I just tried it with my Märzen yesterday. I also, with some trepidation, cut my usual starter size by about a third, bringing it down to about 7% of the total volume in the fermenter. I brew this recipe all the time, so it should be a good test to see if it has a noticeable difference in flavor (pro or con). I'm hoping that the health of the yeast I'm pitching will offset the reduced cell count, and that since the starter is at high krausen it shouldn't be introducing any oxidized wort character. I have high hopes since the starter took off like a rocket (comparatively, for this this yeast at least) and smelled good at pitching time.
Eric B.

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Offline Wort-H.O.G.

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Re: Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter
« Reply #37 on: April 23, 2015, 10:32:08 PM »
Yes Mark has some great knowledge and expertise with yeast. Ive tried his approach for my ales with smaller starter pitched at high krausen and cant say I find anything wrong with it. I have not done it with lagers mostly because of the volume of the starter and it worries about pitching all that DME wort into my lager. one day perhaps I will brave it and try and see .....just haven't gotten there yet  ;D
I just tried it with my Märzen yesterday. I also, with some trepidation, cut my usual starter size by about a third, bringing it down to about 7% of the total volume in the fermenter. I brew this recipe all the time, so it should be a good test to see if it has a noticeable difference in flavor (pro or con). I'm hoping that the health of the yeast I'm pitching will offset the reduced cell count, and that since the starter is at high krausen it shouldn't be introducing any oxidized wort character. I have high hopes since the starter took off like a rocket (comparatively, for this this yeast at least) and smelled good at pitching time.

that's good to know; yes please report back on results....very interested.
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 gmac

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Re: Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter
« Reply #38 on: April 23, 2015, 11:02:11 PM »
I agree completely with which ever side is ultimately proven correct.

Smart man....

Truth is, I'm still gonna do what Denny says regardless.

Offline brulosopher

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Yeast Pitch Rate exBEERiment: Single Vial vs. Yeast Starter
« Reply #39 on: April 24, 2015, 04:53:40 AM »
I agree completely with which ever side is ultimately proven correct.

Smart man....

Truth is, I'm still gonna do what Denny says regardless.

Psst, Denny, hey Denny... tell this dude to do what I say, let's really eff with him ;)