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-naphthol synthetic ester is hydrolized by cells, and the released beta-naphthol is coupled with a diazonium salt (Fast Garnet GBC) in the presence of sodium dodecyl sulfate. The whole procedure is carried out in an aqueous buffer medium, and the resulting azo dye is directly evaluated by absorbance measurement at 524 nm. The analytical results from different assays were adjusted to a fixed cell concentration with a statistical procedure. The method shows good repeatability, reproducibility and 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 improve the aromatic quality of fermented drinks.