Is these yeast starter calculation correct?

Question

I’m making my first yeast starter, and want to confirm my calculations.

• OG = 1,059
• Batch size(post boil) = 9,2 Liters
• Wyeast Ale yeast creating date: 07.des. 2015. (only 36-37 billions cells left..)

According to my calculations, I need 0,3 Liters of water, and 35 grams of spray malt in my starter to reach 100 billion cells (Mr.Malty). I will also add yeast nutrition.

Does this sound right?

Answer 1

Yes, it roughly lines up using my preferred calculator if I use the stir-plate aeration options (the "C.White" option has 124 bn cells, "Kai" has 95 bn cells).

I'll note that the Brewer's Friend calculator does show 56% viability, or about 59 bn cells, not 36 bn.

What sort of aeration method are you using for the starter? That has a huge impact on the amount of cell growth you can expect.

Answer 2

That is a small batch 2.43 gallons.

I too show a yeast viability at 56%

Your starter volume of 300ml seems low. That is more of a proofing volume.

My calculator shows 107bil cell growth if you use 1000ml starter (4oz DME) 1.040sg wort using NO stirplate. Stirplate will bump it up to 167bil cells.

I wouldn't use a Stirplate in this case. Do a 1000ml starter, swirling it manually whenever you walk by it. Once all krausen phases have past, let it settle out and then decant the starter beer off, and just pitch the slurry.