Newbie Yeast Starter Question

[TaoBrewer]

3 days ago, I made a yeast starter with Wyeast 1968 (English ESB Ale) I put a small amount in a quart mason jar (picture) to build another starter and the rest (90% of the smack pac) in a 2L starter I pitched into a new batch of IPA.

After 24 hours, I put the quart jar into the fridge and this is a picture of it this morning.

My question if I drain off the excess wort then pitch the slurry at the bottom into 2 new liters of starter wort how many approximate yeast cells will I have? I probably put no more than 10% of the smack pac into this jar to get it started and the smack pac was less than 30 days old.

What I'm trying to figure is ... is it likely that what I now have in that quart mason jar is as much yeast as comes in a full smack pac or is it a lot less?

 

[Auger]

Your best bet would probably be to run your steps through a calculator like this one and see what it says for cell count:

https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

 

[Auger]

Since I'm bored I'll work through how I'd do it using that calculator -

Starting with a fresh smack pack, make the basic assumption that you are starting with 100B viable cells. You made a starter (you don't say how large, so I'll assume 1L at 1.050 SG), which would result in ~300B cells (if you're using a stirplate, which you didn't specify. If not, it would be somewhat less than that).

You then decanted ~10% of the volume (assuming at time of decant it was homogenously mixed), which means you have about 30B cells in that mason jar. If you pitched this into a new 1L starter at 1.050, you'd end up with 230B cells, which would be enough to pitch for a typical 5gal batch of 1.050 wort.

Obviously I've made a lot of assumtions to get to that conclusion, but you can run through the same exercise with the tool and the true data to get a better estimate.

 

[stratslinger]

Just thinking through logically though, for a second (and working a little algebra into it for good measure):

If you made a starter 3 days ago, then kept 10% of the resulting yeast, in order for that 10% to be equal to what you started with, that starter would have had to have had a 10X growth rate. That doesn't sound like a reasonable expectation.

You left out a bit of important information to determine what your actual growth factor was - and Auger's advice will help illustrate that for you. Did you just put your yeast in starter wort and leave it alone? Did you shake it every time you walked by it? Did you have it on a stir plate?

For a standing starter of 2L, you probably doubled your cell count.
For the best growth projection on a stir plate, you probably almost quadrupled your cell count.

So, your mason jar, if 10% is a good measure, probably holds somewhere between 20 billion and 38 billion cells - roughly 1/5 to 1/3 of a smack pack.

 

[TaoBrewer]

Just thinking through logically though, for a second (and working a little algebra into it for good measure):

If you made a starter 3 days ago, then kept 10% of the resulting yeast, in order for that 10% to be equal to what you started with, that starter would have had to have had a 10X growth rate. That doesn't sound like a reasonable expectation.

You left out a bit of important information to determine what your actual growth factor was - and Auger's advice will help illustrate that for you. Did you just put your yeast in starter wort and leave it alone? Did you shake it every time you walked by it? Did you have it on a stir plate?

For a standing starter of 2L, you probably doubled your cell count.
For the best growth projection on a stir plate, you probably almost quadrupled your cell count.

So, your mason jar, if 10% is a good measure, probably holds somewhere between 20 billion and 38 billion cells - roughly 1/5 to 1/3 of a smack pack.

Thanks! Don't understand why the picture isn't showing as that would help. I put about 10% of the smack pack into the half filled quart mason jar BEFORE I had pitched it into the other 2 liter starter. Nice thing about a mason jar is you can close the lid and shake the crap out of it to get a lot of aeration and I did that about 5 times during a 24 hour period, cracked the lid a bit so it could breathe. I think this actually creates more oxygen than a stir plate.

Based on your recommendation, I think I'll drain the clear wort out of my mason jar, add another half liter to it ... let it grow for another day, refrigerate and then I should probably have enough starter yeast to build a good 2 liter starter for a 1065 gravity IPA.

 

[Auger]

Ok, so you started with ~100B cells out of the smack pack, pitched 90% into a 2L started, then reserved the 10% in the mason jar, and thats where you're at now? So, you have ~10B cells in a mason jar. I wouldn't bet on a whole lot of growth from that, the liquid inside the smack packs is enough to proof the yeast prior to pitching, but from my understanding it doesn't contain enough sugars to really be used as a starter on its own.

And, studies have been done, shaking a starter is definitely better than just letting it sit on a counter, but it's not as good as the constant stirring from a stir plate.

All that being said, your plan is probably sound - step that 10B cells with a .5L starter, then step again to 2L and you should be fine.

 

[TaoBrewer]

Ok, so you started with ~100B cells out of the smack pack, pitched 90% into a 2L started, then reserved the 10% in the mason jar, and thats where you're at now? So, you have ~10B cells in a mason jar. I wouldn't bet on a whole lot of growth from that, the liquid inside the smack packs is enough to proof the yeast prior to pitching, but from my understanding it doesn't contain enough sugars to really be used as a starter on its own.

And, studies have been done, shaking a starter is definitely better than just letting it sit on a counter, but it's not as good as the constant stirring from a stir plate.

All that being said, your plan is probably sound - step that 10B cells with a .5L starter, then step again to 2L and you should be fine.

The 10% of the smackpac was pitched to .5 liter in the quart mason jar and it expanded for a day before I refrigerated it, so it must be higher than 10 billion ... I'm hoping maybe 20-30 billion? If I drain the wort from there and put in another .5 liter I"m hoping I get to 100 billion which would be good to get me to enough if I pitch that to a 2 liter starter.

I've grown a lot of mushrooms which involves a similar process in terms of building a starter culture. and although I have no science to back this up. What I found is there's a HUGE difference in growth of the culture (fungus) in a liquid medium between shaking or stirring and really shaking the crap out of it a few times in a day. It's not a 10 or 20% difference, it's at least a 100% difference. I'm talking about shaking it to the point of the liquid inside the jar looking like it got hit by a 30 foot north shore wave. It took me a long time to figure that out.

Now, I'm finding the same thing with beer/wort. A casual shake or stir isn't the same thing as shaking it with absolutely everything you've got for 30 seconds 3-4 times a day. It takes an absolutely air tight secure lid to do that, though.

Anyway, thanks a lot for your help. I'm just trying to get as many batches as I can out of that smack pack and keep it going without having to buy more yeast. I've done 5 batches now and my last IPA turned out great, primarily, I think, because I pitched a lot more yeast and aerated the wort much, much better than my first 4 that were good, bug not great.

 

[stratslinger]

There's plenty of scientific studies to show that a constantly stirred starter is far more efficient than a shaken one - given that you provide a way for fresh o2 to enter the system. That's what you're trying to ensure here, is constant oxygenation of the yeast cells.

And the kind of growth you're looking for is just not realistic. Play with the calculators mentioned above and experiment for yourself to see.

 

[TaoBrewer]

There's plenty of scientific studies to show that a constantly stirred starter is far more efficient than a shaken one - given that you provide a way for fresh o2 to enter the system. That's what you're trying to ensure here, is constant oxygenation of the yeast cells.

And the kind of growth you're looking for is just not realistic. Play with the calculators mentioned above and experiment for yourself to see.

I used the calculator which shows if I do my first starter with .5 L of wort and 10 billion cells then step 2 with 1 Liter then step 3 with 2 Liters I will have a plenty of Yeast for a good strong IPA (1065 og) with a little leftover to keep the Yeast going.

 

[Auger]

You can also collect and rinse slurry from the fermenter and save that for reuse.

 

[stratslinger]

I used the calculator which shows if I do my first starter with .5 L of wort and 10 billion cells then step 2 with 1 Liter then step 3 with 2 Liters I will have a plenty of Yeast for a good strong IPA (1065 og) with a little leftover to keep the Yeast going.

That's assuming you have zero loss in viability from the second step to the third.

If you plan to take the cells you have in that jar right now, and step them up again with .5L now, then step them up again with 2L in another 3 days, then pitch, you're right.

Wait more than a week or two past that, and you're going to lose viability.

And that's also assuming that you had 10billion cells to start with. How fresh was the pitch you started from?

This is actually a kind of interesting problem, once you break it down. If cell counts were static, or I guess, only grew, then this would be easier to figure out. But since viability tends to degrade - and rather quickly - it'd be interesting to see just how much you'd have to keep feeding your small pitch of yeast in order to maintain enough cells for a good pitch, over time.

This was one of the challenges I always had when I was trying to wash yeast regularly - I had a ton of yeast slurry, but no way to estimate what my actual pitching rate was. It was all guesswork, which is a big part of why I stopped doing it.

 

[TaoBrewer]

That's assuming you have zero loss in viability from the second step to the third.

If you plan to take the cells you have in that jar right now, and step them up again with .5L now, then step them up again with 2L in another 3 days, then pitch, you're right.

Wait more than a week or two past that, and you're going to lose viability.

And that's also assuming that you had 10billion cells to start with. How fresh was the pitch you started from?

This is actually a kind of interesting problem, once you break it down. If cell counts were static, or I guess, only grew, then this would be easier to figure out. But since viability tends to degrade - and rather quickly - it'd be interesting to see just how much you'd have to keep feeding your small pitch of yeast in order to maintain enough cells for a good pitch, over time.

This was one of the challenges I always had when I was trying to wash yeast regularly - I had a ton of yeast slurry, but no way to estimate what my actual pitching rate was. It was all guesswork, which is a big part of why I stopped doing it.

Since I tend to start another brew about every 3-4 weeks, I just need to keep my yeast alive and kicking for less than a month. If I can build a new roughly 300 billion or so starter every month, I'm in good shape. That's what I'm trying to determine. Is there any way to eyeball it?