Is there interest in knowing the cell count of slurries?
It’s something that I find particularly useful especially since discovering how wide the viable cell count can range. A variation of a factor of ten is more common than many brewers would be comfortable with.
If a sample of yeast is mailed to me in a White Labs vial, the testing can be conducted and a report can be written within 24 hours of receiving the sample.
Knowing the cell count of a slurry can save you time and money. A vial of yeast is about $8, and the DME needed for a 2 litter starter is about $3. That’s about one third the cost of a batch of beer.
The tests would include the following:
Viability – The percentage of viable cells of the total cells.
Cell Density – The number of viable cells per milliter and per gram.
Stress Level – The ratio of budding cells to conjoined cells. Budding cells indicate healthy yeast growth while conjoined cells are a sign of yeast stress.
Bacteria Level – percentage of visible bacteria for each yeast cell. Note that some bacteria are smaller than can be seen with a microscope. This is only an estimation of bacteria. It is possible for there to be bacteriological contamination even if zero bacteria are seen.
Alcohol Tolerance – The alcohol level that reduces the viability by half.
In addition I could perform fermentation tests:
Attenuation Rate – The percentage reduction of gravity per day. This is typically tested in a 1.035 specific gravity wort made with Briess Light DME and fermented at ambient air temperature. To better model how you may be using this yeast testing can be done a gravity of up to 1.100.
Total Apparent Attenuation – Percentage of sugar converted to alcohol during fermentation.
Flocculation – percentage of yeast cells that fall out of suspension per day during fermentation.
What do you think, Do you have interest in having a slurry tested?