Storing Yeast

[ultravista]

I rinse my yeast with bottled water, enough to make a slurry in the carboy and bring the cake out of suspension. That slurry then goes into Ball/Mason jars. Depending on the yeast, that's as far as I go.

For example, WLP007, a super clumper, is difficult to wash as it flocs so quickly. Looking at my jars from the last batch, it appears the yeast is on the bottom layer, trub on the middle, and some fine particulate matter on the top. This is much different than Pacman where the trub is the bottom layer and the yeast is near the top.

I had a jar of saved WLP007 that was 6 months old. Built a starter and fermented an Arrogant Bastard with it. Once the starter took off, albeit slow, it did it's job very well.

[WoodlandBrew]

To add to this, for yeast that has been stored for 2 weeks the Mr. Malty calculator says the viability would be around 80%. The "Yeast" book suggests not pitching below 90%. To get the best beer would you recommend: 1) pitching more slurry to account for the viability - per the caclulator, 2) doing a "Revitalization" step as explained in the book, or 3) using the yeast slurry to make a starter and then pitching?

My experience has been that Mr. Malty is very conservative when it comes to refrigeration effects on viability.
In a Saison I did recently pitching the recommended volume of slurry resulted in over pitching by a factor of 20.
http://woodlandbrew.blogspot.com/2012/1 ... cells.html

Viability is more effected by other factors such as fruit and alcohol level
http://woodlandbrew.blogspot.com/2012/1 ... ility.html

[WoodlandBrew]

I rinse my yeast with bottled water, enough to make a slurry in the carboy and bring the cake out of suspension. That slurry then goes into Ball/Mason jars. Depending on the yeast, that's as far as I go.

Some yeast does not wash well. Cell counts on WLP004, WLP566, EC-1118 and S-04 indicate that there is no difference in viability between the layers. Water washing is not effective are removing the dead cells and actually removes 95% of the viable cells.
http://woodlandbrew.blogspot.com/2012/1 ... posed.html

[BDawg]

This is all great stuff, Woodland. Thanks for sharing