# Yeast growing questions

Looked in the yeast section and really couldn’t find the answer to my questions. Hoping they can be answered here.

So I have a smack pack of denny’s favorite 1450. And I want to grow this yeast up before even brewing. Not a yeast starter for one beer. But growth to split between future batches.

So I did a starter with 1.5L starter with 150 grams of dme. The smack pack has 100 billion cells. And looking at mr malty that for a 1.062(I just picked a gravity number to get some figures), than I would need 226 billion cells. And they could be grown with a stir plate and 1L starter.

So what I am getting out, do I get a growth rate of: 225% for a every 1L starter on a stir plate.
Is this correct?

So with my 1.5L starter I will have 337.5 billion cells? Once again, please check my math.

So then I would split and have two containers of 1450 with 168.75 billion cells. Which I would then make actual starters from those two containers for future brews.

And second yeast question? What S.G. do you stop harvesting yeast from? I know I don’t want to take from a 1.080 beer or anything. But how high is really a good stopping point for harvesting?

Thanks a ton. Always appreciate everyones help and knowledge.

It appears that yeast does not grow at the same rate.

Just messed with sg to make me have need 1 smackpack and 1.5L start on stirplate. The gravity was 1.075, with needed 270billion cells.

I guess I don’t understand how you can get 226 billion - 100 billion from the smack = 116 billion from 1L. But only 44 billion from the next 0.5L.

Why would I not get 116/2 = 58 billion every 0.5L

And appears to get worse. 1.086 would need 307 billion. 1 smack pack with 2L starter.

First 1L would give 226-100 = 116 billion grown But then will you do the math on the second liter. 307-226 = 81Billion cells grown

Sean Terrill has an article on his website (or maybe on this forum)
Telling how to calculate the growth by fooling the calculator by setting the viability over 100%, so you’d know exactly what you’d get out of each step.
Might help you figure out the step, split and restep if I understand ya.

[quote=“Scott Miller”]Sean Terrill has an article on his website (or maybe on this forum)
Telling how to calculate the growth by fooling the calculator by setting the viability over 100%, so you’d know exactly what you’d get out of each step.
Might help you figure out the step, split and restep if I understand ya.

Edit: This- http://seanterrill.com/2010/03/08/two-s … culations/[/quote]

Thanks. I will take a look. And yes step, split and restep is actually my goal. I really want to use denny’s 1450 on my next two beers. First one being an amber at 1.063 and then denny’s rye at 1.078. But I still wanted to healthy 1450 around after those two.

Is the 1.063 to high to harvest from? If It is, I will have to step up this batch even more before I would then split it three ways.

I brewed an IPA with an OG of 1.070, removed about a third of the cake when it was finished and dumped a double IPA with a gravity of 1.085 on the cake. I checked it yesterday and it was at 1.016 and tastes fantastic.

As for dividing your your yeast, I think you’d be fine making a large starter, splitting it and making a starter out of each half. You could also make 2 gallons of 1.040 lightly hopped beer with the smack pack and then split the yeast cake for the Amber and RIPA. You wouldn’t have to make any starters and would have a case or so of some session beer to lick on.

[quote=“Glug Master”]I brewed an IPA with an OG of 1.070, removed about a third of the cake when it was finished and dumped a double IPA with a gravity of 1.085 on the cake. I checked it yesterday and it was at 1.016 and tastes fantastic.

As for dividing your your yeast, I think you’d be fine making a large starter, splitting it and making a starter out of each half. You could also make 2 gallons of 1.040 lightly hopped beer with the smack pack and then split the yeast cake for the Amber and RIPA. You wouldn’t have to make any starters and would have a case or so of some session beer to lick on.[/quote]

Awesome, so sounds like I can harvest from the amber and be ok.

Muddy
I have been playing around with culturing and growing yeast for about a year. Want I think I know is yeast just loves to grow. I have pitched very small amounts of yeast (<1 B Cells) into 500ml and grown about 50-100B cells on a stir plate. You can easily take half of the yeast and pitch it into two starters and get twice as much yeast.

Aerate your starter very well and keep the stir plate running. You can store have in the refrig while the first is on the stirplate and switch after a couple of days. Be mindful of sanitation. The yeast will grow to a limit based on the size of the starter. You should be able to get a final concentration of 100-150 M / ml with the stirplate. That’s 150B to 225B per 1.5L starter.

As far as harvesting; as long as the next beer is the same or higher gravity you will be OK. You as want to go from light SRM to darker SRM.

All the best -D

Basically yeast, as do pretty much all microorganisms, grow in logarithmic and not linear manner. So if you start with 1 cell, they’ll go 1-2-4-8-16-32-64-and so on rather than 1-2-3-4-5-6-7-8-9-… so with more volume, there are more nutrients and more volume to dilute the resulting waste products that’ll allow the culture to grow and multiply more before sitting stat and death phases.

That’s with sequential wort additions, right? I don’t think you could get 100x multiplication out of a single starter.

It seems to me stepping it up to a five gallon starter would work fine and you’d have beer too. I’m on my eighth batch with a single pack of 1450 now.

I did a different trick for my wiess beers. I made a simple 1L starter. I pitched it in my hefeweizen, stirred it in well and the refilled my 1L starter with the wort. I pitched that starter the next day in a dunkelweizen. The pitch rates should be pretty close in each batch. Maybe I should have took 1.5L.
edit,
I was way off. At a rate of 9 million/ml Wyeast is showing a growth factor of 4.8. I needed a gallon. At best my dunkel weiss was pitched at 3 million/ml. Oh well, its fermenting strong.