Viability date

[SlaterS]

Does the viability date adjust when you create a starter? I.e. On 12/15/2014 I brewed a 2.5 gallon SMaSH to bump up my heady topper experiment. I harvested some yeast from the fermenter on 1/1/2015. I created a new starter with what was harvested on 1/15/2015. Which date should be used for viability in Mr. Malty's repitching calculator?

 

[WoodlandBrew]

The date used in the calculator is the date that the cells were propagated, so for the cells from the 2nd starter ise the 1/15 date. Although in my experience the viability estimates from Mr. Malty have been pretty far off from what I counted on a hemocytometer. My guess is that your viability is in the ninety's.

The cells for the first starter were mostly propagated a couple of days after the pitch on 12/15. Then it seems that sat under beer for some time before harvesting. The alcohol may have a significant effect on viability. For details see here:
http://www.woodlandbrew.com/2013/01/abv-effects-on-yeast.html

 

[SlaterS]

You're awesome, thanks!