Friday, January 11, 2013

WLP002 Lab results

Strain: WLP002
Testing Date: 1/11/2013
Viability: 86%
Total viable cell density: 1109 million cells per ml
Thick viable cell density:  TBD
Stress level: Low, Similar characteristic flavors to previous batch.
Bacteria level: Moderate, Expect Slight Sourness. (1.62% bacteria per viable cell)


Suggested Pitch Rates:

Pitch rate
Volume of homogenized slurry
Volume of settled cells (Thick cell layer)
100 billion cells for 5 gallons
106 ml
175 billion cells for 5 gallons
187 ml
250 billion cells ifor 5 gallons
267 ml

Viability – Percentage of live cells of the entire cell population
Total Viable Cell Density – The number of viable cells in one milliliter of homogenized slurry.
Thick Viable Cell Density – The number of viable cells in one milliliter of settled cells such as those at the bottom of a starter that has been refrigerated.
Stress Level – A rudimentary assessment of cell health based on cellular morphology. 
Bacteria – The percentage of visible bacteria of the yeast population

Other notes:

This yeast is extremely flocculent.  Viability was counted with Methelyene blue, and a second test was done with a 5% acidic acid chelating solution.  The bacteria level may be a concern.  You might consider acid washing the yeast directly before pitching.  (See next page for more notes)


This report is an evaluation of the sample that was provided.  There are no guarantees.  The sample may perform differently than the slurry for a number of reasons that are beyond control.  Care is taken to provide accurate results, however measurement error due to equipment tolerances, process, and calibration will create deviation in measurement from absolute values. This is not an evaluation of health or safety risks.

1000x magnification.  The image is about 100 micrometers across.

The un-flocculated cells above were used for the cell count.  The stained cells were used for viability.  The combination of the two of these results were used to produce the viable cell count.  Unfortunately acidic acid extracts the methylene blue from the cells so the two cannot be used coincidently.

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