Mr Malty yeast viability calculations
Posted: Thu Jun 16, 2011 2:27 pm
by Neddy
I was fooling around with Jamil's yeast calculator tonight. I was thinking about brewing a Bo Pils next week using a pack of yeast I bought a few weeks ago. Production date on the yeast is 4/13/11 when plugged into Jamil's calculator shows a 55% viability which means I'd need a GIANT starter.
I know jamil's done his homework but does yeast viability really drop nearly 50% after 2 months from production when stored cold in the fridge?
Re: Mr Malty yeast viability calculations
Posted: Thu Jun 16, 2011 2:30 pm
by dunleav1
Neddy wrote:I was fooling around with Jamil's yeast calculator tonight. I was thinking about brewing a Bo Pils next week using a pack of yeast I bought a few weeks ago. Production date on the yeast is 4/13/11 when plugged into Jamil's calculator shows a 55% viability which means I'd need a GIANT starter.
I know jamil's done his homework but does yeast viability really drop nearly 50% after 2 months from production when stored cold in the fridge?
Yes.
Re: Mr Malty yeast viability calculations
Posted: Thu Jun 16, 2011 2:37 pm
by Lichtersnatch
I believe Jamil used Methylene blue testing for the calc (from what I've heard 2nd hand), which can be a little bit inaccurate under 80% or 90% viability. But having said that... yes, liquid yeast goes downhill fast.
Re: Mr Malty yeast viability calculations
Posted: Thu Jun 16, 2011 5:25 pm
by siwelwerd
Neddy wrote:Production date on the yeast is 4/13/11 when plugged into Jamil's calculator shows a 55% viability which means I'd need a GIANT starter.
Or you could step it up a couple times.
Re: Mr Malty yeast viability calculations
Posted: Thu Jun 16, 2011 7:09 pm
by ntillemans
siwelwerd wrote:Neddy wrote:Production date on the yeast is 4/13/11 when plugged into Jamil's calculator shows a 55% viability which means I'd need a GIANT starter.
Or you could step it up a couple times.
Stepping up is a great idea when you need to grow a lot of yeast.
Doesn't hurt to have a 5L Erlenmeyer flask either.
Sometimes it takes both...sometimes...