Lugol stain and glycogen health

[ipscman]

George Fix, (Principles of Brewing Science or An Analysis of Brewing Techniques - I forget which) as well as Hardwick, and later Priest (Handbook of Brewing) mention using Lugol stain/solution to determine glycogen health in stored yeast. The normal approach is to stain cells on a microscope slide and see if the color changes to dark brown, indicating glycogen health. Does anyone know if you can use the stain on a blob of yeast slurry instead and get the same results (i.e., without the use of a microscope)?

 

[ajdelange]

Conceptually it should. Put a little of the slurry in a test tube with some water, add a couple of drops of Lugol and shake. The color developed would be proportional to the amount of glycogen. Apparently microbiologists do (or did) something like this.