GigaFemto
Grandmaster Brewer
Sorry if this has been hashed out already, but I couldn't find it on the forum. I have some 4-month old White Labs WLP004 yeast (packaged 3/31/2017, says use by 9/27/2017) that has been refrigerated the whole time. BeerSmith 2.3.12 says the viability is 61%. I usually use the Brewer's Friend Calculator (https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/ ) because it allows you to do two-stage starters. The viability estimated there is 13%. These are wildly different. If I have 13% viability and only do a single-stage starter (I can do 1.5 liter max) I won't have as many cells as I want. On the other hand, if I do a two-stage starter and the viability is 61%, I will have twice as many cells as I want, and my experience with over-pitching has not been good.
I know that there is no good way to calculate yeast viability accurately, but the difference between 13% and 61% seems unreasonable. Does anyone have any experience to indicate which of these would be better to use?
--GF
I know that there is no good way to calculate yeast viability accurately, but the difference between 13% and 61% seems unreasonable. Does anyone have any experience to indicate which of these would be better to use?
--GF