A RAPID SPECTROPHOTOMETRIC METHOD TO DETERMINE ESTERASE-ACTIVITY OF YEAST-CELLS IN AN AQUEOUS-MEDIUM

A new rapid method to determine the total esterase enzymatic activity of yeast cells is proposed. In a sodium phosphate buffer a beta-naphth ol synthetic ester is hydrolized by cells, and the released beta-napht hol is coupled with a diazonium salt (Fast Garnet GBC) in the presence of sodium dodecyl sulfate. The whole procedure is carried out in an a queous buffer medium, and the resulting azo dye is directly evaluated by absorbance measurement at 524 nm. The analytical results from diffe rent assays were adjusted to a fixed cell concentration with a statist ical procedure. The method shows good repeatability, reproducibility a nd detectability, and it requires simple equipment and instruments. It is therefore suitable both for routine analysis, as industrial yeast strain screening, and for yeast physiological studies, in order to imp rove the aromatic quality of fermented drinks.