Cell count from yeast starter

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Falcor

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I'm curious about the cell count in a yeast starter compared to the cell count if the yeast were to reproduce after pitched into wort. For example, lets say I create a starter with x amount of yeast and the starter ends up with 4x cell count. Now lets say I pitch x amount of yeast into fermenter without a starter, will there eventually be 4x amount of yeast also or less? The 4 I'm using is a completely random guess, really I just want to be able to compare how much yeast there is with a starter vs no starter.

The reason I ask is this: I did a 2.5 gallon batch a few weeks ago and used WLP008. I didn't do a starter and should have only used 1/2 the vial, but accidentally used 3/4. So now I have 1/4 vial that I don't know what to do with. If i do a starter for my next 2.5 gallon batch will it build up a high enough cell count? If not I guess I'll just have to trash the rest of this vial.
 
Use a multistep starter. Make a 1000mL starter, then bump it up to 2000mL by adding more wort to it. More yeast never hurts.
 
I would pitch the whole vial on the 2.5 gallon batch, then use the yeast from that for a 5 gallon batch. Once I open a vial, I use the whole thing, once you've had air in it, or anything else, you don't know whats going on inside that vial anymore. A brand new, sealed vial is a pure culture.
 
Thanks guys, more questions though...

Suthrncomfrt1884 said:
Use a multistep starter. Make a 1000mL starter, then bump it up to 2000mL by adding more wort to it. More yeast never hurts.
Click to expand...

What type of container is typically used for a starter this size? A 1 gallon glass bottle?

enderwig said:
I would pitch the whole vial on the 2.5 gallon batch, then use the yeast from that for a 5 gallon batch. Once I open a vial, I use the whole thing, once you've had air in it, or anything else, you don't know whats going on inside that vial anymore. A brand new, sealed vial is a pure culture.
Click to expand...

How about making 2 starters from a vial. The one I don't use I could put it in the fridge after a few days and then reprime it a couple days ahead of time with a bit more wort?

And I assume I need to keep the starter around 65 - 70 degrees while its active?
 
Yeast reproduce to a certain concentration after which fermentation starts. The max concentration of yeast achieved is bound by the gravity of the wort, amount of available oxygen, and amount of available nutrients such as free nitrogen, zinc, or amino acids. Pitching without a starter may or may not yield the same number of yeast cells before fermentation begins depending on whether there is sufficient oxygen and nutrients available to support the number of generations that need to be produced.

A starter with unlimited oxygen (eg. on a stir plate) and plenty of available nutrients presents ideal conditions for yeast growth, and should yield between 10M and 15M cells per mL/*P of wort. For a 1.040 wort and a 1L starter that means you would get 100B to 150B of cells regardless of the amount pitched into the starter. The drawback of starting from fewer cells is that you will have more generations, and each generation depending on the strain can take between 1 and 3 hours to reproduce. Longer lag times means a higher percentage of unwanted nasties will end up in the starter and eventually your beer, since these guys (bacteria) can reproduce as frequently as once every 15 minutes or so. Once fermentation begins bacteria growth in inhibited, and once alcohol concentration reaches 2% or greater most bacteria die. This is the main reason why it is recommended to only step up by a factor of 10 or so in cell counts. For instance, I'll pitch a slant (which probably has 1M viable cells on it) into 250mL of *sterile* wort on the stir plate, wait 24 hours, and then pitch that into 1-2L of wort on the stir plate. After 24 more hours my starter is ready to pitch into 5 gallons with 150B-300B active yeast cells.

Wort doesn't present good conditions for yeast growth, unless you are making a 1.040 beer and you use an O2 stone to saturate the wort with oxygen before pitching. Even so I would still make a starter unless the yeast in question is very fresh, since yeast stored for long periods tends to have a long lag time increasing your chances of developing an unwanted infection. The recommended pitching rate is .75-1M cells/mL/*P for ales, and 1.5-2M cells/mL/*P for lagers. I typically aim for the upper end of the range for beers over 1.070 starting gravity, since the high sugar concentration both stresses the yeast and reduces the amount of oxygen I can introduce into the wort. Jamil's pitching calc
(Mr Malty Pitching Rate Calculator) will give you the .75M or 1.5M numbers depending on whether you select ale or lager.
 
This is exactly what I needed, but I'm having a hard time working through the numbers. Help me figure out what I'm doing wrong here...

You say 1L starter of 1.040 wort will give 100 - 150 billion cells. So 1L = 1000mL and 1.040 = 10P. From this I get that I should have 10M to 15M cells per (1000/10) = 10 to 15M per (100). 10,000,000 * 100 is only 1 billion, how did you get 100 billion?

Also not sure where you get the .75M that mr malty uses for ales. I typed in 2.5 gallon batch with 1.06 OG, it says I need 104B cells. 2.5 gallon as liters is 3.8 * 2.5 = 9.5L, or 9500mL. 1.060 is close enough to 15P. So 750,000 per 9500/15 = 475M, not 104B.

What am I missing?
 
Saccharomyces said:
Yeast reproduce to a certain concentration after which fermentation starts. The max concentration of yeast achieved is bound by the gravity of the wort, amount of available oxygen, and amount of available nutrients such as free nitrogen, zinc, or amino acids. Pitching without a starter may or may not yield the same number of yeast cells before fermentation begins depending on whether there is sufficient oxygen and nutrients available to support the number of generations that need to be produced.

A starter with unlimited oxygen (eg. on a stir plate) and plenty of available nutrients presents ideal conditions for yeast growth, and should yield between 10M and 15M cells per mL/*P of wort. For a 1.040 wort and a 1L starter that means you would get 100B to 150B of cells regardless of the amount pitched into the starter. The drawback of starting from fewer cells is that you will have more generations, and each generation depending on the strain can take between 1 and 3 hours to reproduce. Longer lag times means a higher percentage of unwanted nasties will end up in the starter and eventually your beer, since these guys (bacteria) can reproduce as frequently as once every 15 minutes or so. Once fermentation begins bacteria growth in inhibited, and once alcohol concentration reaches 2% or greater most bacteria die. This is the main reason why it is recommended to only step up by a factor of 10 or so in cell counts. For instance, I'll pitch a slant (which probably has 1M viable cells on it) into 250mL of *sterile* wort on the stir plate, wait 24 hours, and then pitch that into 1-2L of wort on the stir plate. After 24 more hours my starter is ready to pitch into 5 gallons with 150B-300B active yeast cells.

Wort doesn't present good conditions for yeast growth, unless you are making a 1.040 beer and you use an O2 stone to saturate the wort with oxygen before pitching. Even so I would still make a starter unless the yeast in question is very fresh, since yeast stored for long periods tends to have a long lag time increasing your chances of developing an unwanted infection. The recommended pitching rate is .75-1M cells/mL/*P for ales, and 1.5-2M cells/mL/*P for lagers. I typically aim for the upper end of the range for beers over 1.070 starting gravity, since the high sugar concentration both stresses the yeast and reduces the amount of oxygen I can introduce into the wort. Jamil's pitching calc
(Mr Malty Pitching Rate Calculator) will give you the .75M or 1.5M numbers depending on whether you select ale or lager.
Click to expand...



This is a great freakin' post. Chockfull'o'info. I'm getting ready to do my first step up from a slant for a batch next week. Before I read this post, I was clueless. After I read this post, I feel confident I can step up from my slant to a starter and pitch a proper amount of yeast.

+1 vote for HBT Post Hall of Fame.

:rockin:
 
Of course, now that I've given Sacch uber props, I have a question.

If the yeast are reproducing to a certain concentration in a stirplate starter regardless of initial cell count pitched, how come Mr. Malty's pitching rate calculator has you make a larger starter if your viability drops?
 
AND Why does it say you need 2 vials of yeast even for a stir plate.

Just a thought....

David sitting here having an ESB under the air conditioner. :)

Edit: Saccharomyces, I have read what you said a few times in books, but
you write it so I can understand it. Thank you
 
JKoravos said:
Of course, now that I've given Sacch uber props, I have a question.

If the yeast are reproducing to a certain concentration in a stirplate starter regardless of initial cell count pitched, how come Mr. Malty's pitching rate calculator has you make a larger starter if your viability drops?
Click to expand...

I'm not sure. My experience has been that making a starter from really old yeast doesn't work very well if you don't have a stir plate. With a stir plate, I can pitch a year old expired tube of yeast and still have a good starter in 24-36 hours. So when I use Mr. Malty calc I always set the viability to 95%.

EDIT: the best resource I have found is this page: http://www.maltosefalcons.com/tech/yeast-propagation-and-maintenance-principles-and-practices
 
So when you say work towards a 2000ML starter is that including the wort or only the slurry? If it only the slurry or yeast, that is a TON of yeast!!!

I usually have been starting with a full vial of white labs and adding it to a 1000ml flask. Letting it run its course on my stirplates, until I no longer see bubbles or krausen. Then adding more new wort to bring the volume to 2000ml. After that new wort is worked through I put it in the fridge over night and I found that I get about 3/4 of an inch of yeast cake at the bottom of the flask.

I planned on siphoning off the wort from this cake and using that slurry to pitch.

Am I looking at this the right way?
 
msheraw said:
So when you say work towards a 2000ML starter is that including the wort or only the slurry? If it only the slurry or yeast, that is a TON of yeast!!!

I usually have been starting with a full vial of white labs and adding it to a 1000ml flask. Letting it run its course on my stirplates, until I no longer see bubbles or krausen. Then adding more new wort to bring the volume to 2000ml. After that new wort is worked through I put it in the fridge over night and I found that I get about 3/4 of an inch of yeast cake at the bottom of the flask.

I planned on siphoning off the wort from this cake and using that slurry to pitch.

Am I looking at this the right way?
Click to expand...

Exactly. Though you have enough yeast you really can go straight to 2000mL from the package. I've even done 2x 2000mL from a single package... pour in half the tube, and put it back in the fridge to add the rest to the second starter the next day. The real key is the stir plate -- you get up to 6x more yeast from the stir plate than by any other means.
 
Great thread guys! Sac, you're really giving credence to your name. You really understand the crap out of these little guys.

This thread has definitely moved a stirplate to the top of my DIY list. I'm thinking I need to run to the electronics store today to pick up a few essentials so I can start tonight.

I'm looking in to beginning to harvest yeast from certain beers (namely Bell's Two-Hearted) and this thread is really going to help me. Thanks again!
 

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