The 5-carboxyfluorescein diacetate (CFDA) esterase substrate is used to determine the vitality of yeast. CFDA penetrates the cell membranes of living cells, the diacetate groups are cleaved from non-specific esterases and a fluorescent, charged substrate form (carboxyfluorescein) is obtained that stains the cells in green and flows out of the cells very slowly. In parallel, in a separate sample with yeast cell suspension, the total number of yeast cells was determined using the fluorescent dye Sofia Green. To determine the total number of cells, it is necessary for the membrane of living cells to become permeable to Sofia Green. This is achieved by mixing the cell suspension with a lysis reagent for 10 minutes. Sofia Green penetrates through damaged cell membranes, binds to core nucleus, and cells with damaged membranes turn green.