A rapid and simple method for the determination of glycogen in yeast

Abstract

A rapid, simple, adaptable and widely applicable procedure for the determination of glycogen in yeast is described. The method exploits the known fact that an aqueous solution of iodine/potassium iodide will stain yeast cells. The intensity of staining has been shown to be proportional to the amount of glycogen present in samples of yeast representing four strains of Saccharomyces cerevisiae. Therefore levels of yeast glycogen can be determined quantitatively by measurement of absorbance, or approximated by visual examination of the yeast‐iodine suspension. Such a convenient procedure should enable the brewer (i) to compensate for variations in the glycogen content between different batches of pitching yeast, thereby achieving greater reproducibility in fermentations, and (ii) to monitor changes in yeast composition during storage as a basis for developing improved yeast handling procedures. 1983 The Institute of Brewing & Distilling