WoodlandBrew
Well-Known Member
There seems to be room for research on the effects of refrigeration on yeast slurry. There are online calculators that will produce a viability number based on storage time , but the research behind these calculations seems to be lacking.[1] Work has been done examining the effects over the course of several days[2][3] but storage over several months has not been well documented that I know of.
The goal of this experiment would be to better assess both the viability and vitality of stored yeast so that pitch rate can be adjusted accordingly.
Is there a study that has been conducted on the viability and vitality of yeast stored for several months?
What conditions should be emulated?
What metrics might be important to evaluate?
My current plan is to rehydrate[4] and store four different strains of ale yeast. These will be used to inoculate wort at intervals ranging from one week to one year. Viability [5]will be measured prior to inoculation of each test. Cell density [6] will be monitored daily. Residual extract will be measured after fermentation completion.
[1] Mr. Malty, Yeast Calc, Brewers Friend
[2] Murray, "The Effect of Yeast Storage Conditions on Subsequent Fermentations" 1984
[3] www.woodlandbrew.com/2012/12/refrigeration-effects-on-yeast-viability.html
[4] rehydrated yeast provides a more repeatable source than cultures that have previously been stored for an indeterminate amount of time before reaching the consumer.
[5] Viability will be assessed using Methylene Blue staining www.woodlandbrew.com/2012/11/counting-yeast-cells-to-asses-viability.html
[6] Cell density will be measured with an optical cell density meter www.woodlandbrew.com/2014/07/cell-density-meter.html
The goal of this experiment would be to better assess both the viability and vitality of stored yeast so that pitch rate can be adjusted accordingly.
Is there a study that has been conducted on the viability and vitality of yeast stored for several months?
What conditions should be emulated?
What metrics might be important to evaluate?
My current plan is to rehydrate[4] and store four different strains of ale yeast. These will be used to inoculate wort at intervals ranging from one week to one year. Viability [5]will be measured prior to inoculation of each test. Cell density [6] will be monitored daily. Residual extract will be measured after fermentation completion.
[1] Mr. Malty, Yeast Calc, Brewers Friend
[2] Murray, "The Effect of Yeast Storage Conditions on Subsequent Fermentations" 1984
[3] www.woodlandbrew.com/2012/12/refrigeration-effects-on-yeast-viability.html
[4] rehydrated yeast provides a more repeatable source than cultures that have previously been stored for an indeterminate amount of time before reaching the consumer.
[5] Viability will be assessed using Methylene Blue staining www.woodlandbrew.com/2012/11/counting-yeast-cells-to-asses-viability.html
[6] Cell density will be measured with an optical cell density meter www.woodlandbrew.com/2014/07/cell-density-meter.html