Yeast Viability Measurements in Fermentation Studies
FlowCAM® Application Note #105
Yeast Viability Measurements in
Fermentation Studies
Objective
An important component of fermentation processes is to continually monitor yeast growth and viability. The most common method for doing this is using the ASBC hemocytometer count method. In this method, samples are taken from the fermentation vessel, stained with methylene blue, and then counted manually under a microscope using a hemocytometer.
While this method is well known and documented, it is, at best, an estimate based upon a very small sample count.
The hemocytometer, when viewed under a microscope, presents a grid of measurement areas as seen below.
= Grid Cell Counted
= Grid Cell Not Counted
Method
The FlowCAM® is ideally suited to automate this process. It can image, count and measure thousands of individual yeast cells in the time it takes for an operator to count only tens of cells using the hemocytometer method. The VisualSpreadsheet© software automatically produces a count of live, dead and budding yeast cells without any operator being involved. This normalizes out human error, and provides extremely precise and repeatable results. Further, the numbers have a much higher statistical significance due to the larger data populations obtained by the FlowCAM.
The yeast samples are taken from the fermentation vessel and prepared just as they are for the hemocytometer method by staining with methylene blue.
The sample is then run through the
FlowCAM in autoimage mode at seven frames per second as it flows through the flow cell. Every yeast cell is imaged, stored and measured during acquisition.
Because of the time involved for an operator to do manual counting, only a small number of actual grid cells are counted, with the results then being interpolated as an average number.
Not only is the sample size very small, which yields low statistical significance, but it is known that up to 25% error
can
Yeast Viability Measurements in
Fermentation Studies
Objective
An important component of fermentation processes is to continually monitor yeast growth and viability. The most common method for doing this is using the ASBC hemocytometer count method. In this method, samples are taken from the fermentation vessel, stained with methylene blue, and then counted manually under a microscope using a hemocytometer.
While this method is well known and documented, it is, at best, an estimate based upon a very small sample count.
The hemocytometer, when viewed under a microscope, presents a grid of measurement areas as seen below.
= Grid Cell Counted
= Grid Cell Not Counted
Method
The FlowCAM® is ideally suited to automate this process. It can image, count and measure thousands of individual yeast cells in the time it takes for an operator to count only tens of cells using the hemocytometer method. The VisualSpreadsheet© software automatically produces a count of live, dead and budding yeast cells without any operator being involved. This normalizes out human error, and provides extremely precise and repeatable results. Further, the numbers have a much higher statistical significance due to the larger data populations obtained by the FlowCAM.
The yeast samples are taken from the fermentation vessel and prepared just as they are for the hemocytometer method by staining with methylene blue.
The sample is then run through the
FlowCAM in autoimage mode at seven frames per second as it flows through the flow cell. Every yeast cell is imaged, stored and measured during acquisition.
Because of the time involved for an operator to do manual counting, only a small number of actual grid cells are counted, with the results then being interpolated as an average number.
Not only is the sample size very small, which yields low statistical significance, but it is known that up to 25% error
can