Making a yeast starter

[nickey]

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Hi Kal,
Yep I'm confused now. Here is an image from brewers friend. I don't know where I am going wrong.

[kal]

What's the information above that?
What size is your flask?

Kal

[kal]

What's the information above that?
What size is your flask?

Kal

[nickey]

I have a 5L flask. Here is what I entered above.

[kal]

You're not doing anything wrong. Go ahead with what the calculator shows and you'll end up with 777B cells.

Breakdown:

You want to make 12 gallons of 1.065 beer. You need 722B cells according to the calculator and your yeast pack has 38B to start with. Your flask is 5L in size.

In "Starter - Step 1" if you type in various starter sizes (1.036 gravity) you'll see that you need s starter step 1 size of 5.1L to hit that 722B cell target.
You can't put 5.1L in a 5L flask. Maybe you can get close, but you need some headspace too as it can get very foamy. I never like to go above 4L in a 5L flask.

So, if in "Starter - Step 1" if you type in 2L instead you'll end up with 306B cells from that first step.
Then in "Starter - Step 2" if you type in 3.1L you'll end up with 722B cells from the two steps combined.
That's what you want to do. Ferment step 1 with 2L in the flask using the yeast pack, let it settle out in the fridge after it's done, decant, and then ferment step 2 with 3.1L in the flask *with the 306B cells from step 1*, let it settle out in the fridge...

Kal

[kal]

You're not doing anything wrong. Go ahead with what the calculator shows and you'll end up with 777B cells.

Breakdown:

You want to make 12 gallons of 1.065 beer. You need 722B cells according to the calculator and your yeast pack has 38B to start with. Your flask is 5L in size.

In "Starter - Step 1" if you type in various starter sizes (1.036 gravity) you'll see that you need s starter step 1 size of 5.1L to hit that 722B cell target.
You can't put 5.1L in a 5L flask. Maybe you can get close, but you need some headspace too as it can get very foamy. I never like to go above 4L in a 5L flask.

So, if in "Starter - Step 1" if you type in 2L instead you'll end up with 306B cells from that first step.
Then in "Starter - Step 2" if you type in 3.1L you'll end up with 722B cells from the two steps combined.
That's what you want to do. Ferment step 1 with 2L in the flask using the yeast pack, let it settle out in the fridge after it's done, decant, and then ferment step 2 with 3.1L in the flask *with the 306B cells from step 1*, let it settle out in the fridge...

Kal

[nickey]

Glad to know I wasn't messing up. I will decant between step 1 and 2.
I was hoping to bypass that and use the 2L volume of liquid already in the flask and just add 1.5 liters with the 11.8 oz of DME in it to that amount.

Thanks for the help

[kal]

Now I understand what you were planning!

Using only 1.5L for the second step instead of 3.5L but keeping the DME amount the same means that the gravity of the starter will be much higher than the recommended 1.036. I plugged the numbers in and your second step would actually be 1.084 gravity. You can certainly do that, but then yeast growth will be reduced and the yeast stressed. I wouldn't recommend it.

If you really don't want to multi-step, I'd recommend using the required amount of DME you need to reach reach 722B in a single step. That would be better as that starter would have lower gravity than your 1.036 and 1.084 steps. I plugged in the numbers and if you do a 4L starter and want to hit 722B cells you need 17.3 oz of DME and it'll produce a 1.046 starter instead of the optimal 1.036. That's pretty close. If you can manage a 4.5L starter that's even beer as it'll only be 1.041.

When something's close to fitting in a single step I tend to bump the gravity up slightly. No big deal. Slightly reduced yeast production maybe, but you save a step. Remember that per my guide, yeast starter calculators are pretty much just guestimates anyway.

Kal

[kal]

Now I understand what you were planning!

Using only 1.5L for the second step instead of 3.5L but keeping the DME amount the same means that the gravity of the starter will be much higher than the recommended 1.036. I plugged the numbers in and your second step would actually be 1.084 gravity. You can certainly do that, but then yeast growth will be reduced and the yeast stressed. I wouldn't recommend it.

If you really don't want to multi-step, I'd recommend using the required amount of DME you need to reach reach 722B in a single step. That would be better as that starter would have lower gravity than your 1.036 and 1.084 steps. I plugged in the numbers and if you do a 4L starter and want to hit 722B cells you need 17.3 oz of DME and it'll produce a 1.046 starter instead of the optimal 1.036. That's pretty close. If you can manage a 4.5L starter that's even beer as it'll only be 1.041.

When something's close to fitting in a single step I tend to bump the gravity up slightly. No big deal. Slightly reduced yeast production maybe, but you save a step. Remember that per my guide, yeast starter calculators are pretty much just guestimates anyway.

Kal

[nickey]

Oh, I get it now. I was thinking about growing cells and did not consider the stress on the yeast from the high gravity.
Thanks for making it clear to me. I know that I should have, but that was a part of the calculator that I did not understand.

Thanks again,

[kal]

You're welcome! Cheers and happy brewing!

Kal

[kal]

You're welcome! Cheers and happy brewing!

Kal

[nickey]

Kal,

While I am figuring this out a little better I want to ask, after what period of time can a starter be pulled from the stir plate? I have left them on a lot longer than they probably should have been but never knew when to tell that it had done all it was going to do. Is it different for different yeast strains or is there a way to identify when the starter has been completed?

thanks

[kal]

Hi Nickey - see my guide, specifically step 5 "Pitch yeast and ferment until completion": https://shop.theelectricbrewery.com/pages/making-a-yeast-starter#STEP_5_Pitch_yeast_and_ferment_until_complete

I explain how the colour gets lighter and the temperature drops. I include pictures as well. Cheers!

Kal

[kal]

Hi Nickey - see my guide, specifically step 5 "Pitch yeast and ferment until completion": https://shop.theelectricbrewery.com/pages/making-a-yeast-starter#STEP_5_Pitch_yeast_and_ferment_until_complete

I explain how the colour gets lighter and the temperature drops. I include pictures as well. Cheers!

Kal

[nickey]

Thank you Kal,
I have read all this stuff but guess it just hasn't sunk in yet.