Yeast Starter Help

[str1p3s]

I'm planning my first lager, a 5.5 gallon Maibock.

The target OG is 1.072.

I have a 2L flask and stir plate.

Here's my plan, please take a look and provide any input! The yeast numbers are from brewersfriend.com yeast calculator (according to that calculator, I need 547B cells):

1) Make a 1.75L starter with 1 pack, turning 100B cells into 352B

2) After 24 hours, split it in half and save 176B in mason jar in fridge

3) Make another 1.75L starter with remaining 176B, turning that into 428B

4) Put flask in fridge with mason jar

5) pitch them both (176B + 428B = 604B) on brew day


Anyone have any advice or critique of this plan?

Is 57B over my target considered over pitching by too much?

Also, as kind of a side question, when fermenting wort, common knowledge is the beer can be done fermenting anywhere from a few days to a few weeks. Why does it seem like common knowledge is 24 hours is enough time for a starter?


As always, thanks for any input

 

[JonM]

I went through something similar when planning my first lager and having only a 2L flask, and I eventually said "oh, screw it" and got two packs of 34/70, and it worked beautifully. Maybe that's an option here?

 

[flars]

57 billion extra cells would not be considered an over pitch.

You may lose some yeast and wort with 1.75 liters in a 2 liter flask if this yeast produces an active krausen on the stir plate. A greater amount of yeast would be lost in step 2 with the addition of yeast and some wort bringing the total volume even higher.

I would cut the volume back closer to 1.5 liters or just use a larger container with the shake and swirl method of aeration and suspending the yeast. A large pickle type jar would work very well.

I've had WY 1332 take almost three days to finish fermentation on a stir plate. Some yeast strains finish quickly but not all of them. General time rules can be considered suspect for their validity.

 

[HopHeavy]

1) Make a 1.75L starter with 1 pack, turning 100B cells into 352B

2) After 24 hours, split it in half and save 176B in mason jar in fridge

3) Make another 1.75L starter with remaining 176B, turning that into 428B

4) Put flask in fridge with mason jar

5) pitch them both (176B + 428B = 604B) on brew day


Anyone have any advice or critique of this plan?

Is 57B over my target considered over pitching by too much?

The logic on volumes seems pretty sound on the development of the split starter. (I would ensure you chill and decant both sides of the split before stepping up the starter.) However, there might be a couple flaws in the rest of your plan...

You might suffer some yeast loss in blowoff because the capacity is pretty tight in 2L flask for a 1.75 L starter.

Your initial step to 352 Billion cells is certainly based upon a brand spanking new vial of yeast. You ought to adjust the calculator to reflect the date on the vial.

No overpitch here... you will find the range can change on that pitch between calculators (or even within the same calculator if different rates are selected

Also, as kind of a side question, when fermenting wort, common knowledge is the beer can be done fermenting anywhere from a few days to a few weeks. Why does it seem like common knowledge is 24 hours is enough time for a starter?

You pitch an enormous density of cells into starter wort as opposed to your brewed wort. This certainly makes for a speedier fermentation. On top of that, your stir plate definitely improves the distribution of yeast throughout wort and thereby improve access to sugars and nutrients. Spinning also drives CO2 from the solution. Finally, there is a school of thought that the spinning provides continuous oxygen exchange into the starter. While there is increased surface exposed to air, I don't know how much more oxygen is taken in. All of these things serve to speed the starter along.

 

[str1p3s]

I've had WY 1332 take almost three days to finish fermentation on a stir plate. Some yeast strains finish quickly but not all of them. General time rules can be considered suspect for their validity.

How do you know when it's done? I've made one starter before and there wasn't much krausen (at the times I looked at it) and when it's on the stir plate everything is mixing around so nothing settles out.


Also, for the volume question, I would crash and decant after the first step and then before I pitch.

My initial calculations started with 1.5L and it wasn't enough. I didn't want to have to do 3 step ups.

 

[flars]

How do you know when it's done? I've made one starter before and there wasn't much krausen (at the times I looked at it) and when it's on the stir plate everything is mixing around so nothing settles out.


Also, for the volume question, I would crash and decant after the first step and then before I pitch.

My initial calculations started with 1.5L and it wasn't enough. I didn't want to have to do 3 step ups.

This yeast starter had a large krausen. Had a yeast overflow. I took the flask off the stir plate when the krausen dropped. Still had krausen forming for the next 24 hours with the shake and swirl method to check for completion.