Yeast Starter Question

[WestMichiganSteelheader]

I built a yeast starter earlier in the week using WPL001 pure pitch which is advertised as 7.5 million cells per ml. The best buy date is July 29, 2023. The jars in the above picture are 113 ml and I estimate there will be about 30 ml of yeast once settled.

How do I estimate the number of cells in each jar? Would 30 ml of yeast be sufficient for 5.25 gallons of ale with an OG of 1.057?

 

[IslandLizard]

It certainly looks like you had some growth, from the original 40-50ml to 3x 30-40 ml.
How big was your starter volume?

Did you use a yeast calculator when making the starter?
Such as this one: Homebrew Dad's Online Yeast Starter Calculator

 

[WestMichiganSteelheader]

It certainly looks like you had some growth, from the original 40-50ml to 3x 30-40 ml.
How big was your starter volume?

Did you use a yeast calculator when making the starter?
Such as this one: Homebrew Dad's Online Yeast Starter Calculator

I had approximately 1,000 ml of water to 100 grams of DME.

I did not use a calculator other than the one at White Labs that indicates how many bags of pure pitch is required.

I will check out the link provided. Thank you.

 

[IslandLizard]

Did you use a stir plate?

There's some leeway in the numbers, one being PurePitch packs holding their cell count (viability) better than other packaging. To reflect that, put the production date at 4/29/23 rather than 1/29/23.

 

[Bassman2003]

Well, one vial is for one 5 gallon batch of beer. A 2 liter 1.035 starter is thought to basically double your yeast count when beginning with a homebrew vial of yeast. So I do not think you grew enough to pitch three different batches. You might have enough for two ok pitches or one solid pitch.

 

[WestMichiganSteelheader]

Did you use a stir plate?

There's some leeway in the numbers, one being PurePitch packs holding their cell count (viability) better than other packaging. To reflect that, put the production date at 4/29/23 rather than 1/29/23.

Yes, used a stir plate.

 

[IslandLizard]

Yes, used a stir plate.

Ah, good!
Here's what I get, using 01/29/23 as the yeast packaging date, but with only 6% decline in vitality per month (PurePitch yeast), for a total of 18% over the past 3 months. I therefore manually entered 82 (100-18) into the [Viability %] box.

So I do not think you grew enough to pitch three different batches. You might have enough for two ok pitches or one solid pitch.

Exactly!
Since most of the yeast is now freshly made, you can probably pitch half (one and a half jar) of your newly made starter, and save the other half for next time of better, to make another starter and pitch some of that. And so on.

Or make a 24-48 hrs vitality starter with one of the jars plus 1 liter starter wort. Pitch as is, do not cold crash/decant.

Therefore, if you can, making 1.6-2 liter starters would be more productive. For example, here's the 2 liter version:

That's enough for 2 solid 5 gallon pitches of 1.060 wort. And always save some out to make a next starter round from. Especially in these days where a sleeve of yeast now runs around $12. Plus shipping if you can't get it locally.