Activities and morphology of saccharomyces cerevisiae

Application of high isostatic pressure in biological and food researches has been extensively studied in the last decade. It has recently been proposed that high isostatic pressure might be applied to increasing both the activity and stability of several enzymes. In this research the enzymatic activity, CFU and morphological changes of commercial S.cerevisia under 0, 50, 75, 100, 125 and 150 MPa pressure at 5, 10, 15 minutes pressurization after 24 hours keeping in 4C° were studied. The results statistically analyzed and showed that 50 MPa pressure didn’t affected on yeast cells but increased the enzymatic activity in 75 and 100MPa pressure at 10 and15 minutes pressurization. In addition the images of scanning electron microscope (SEM) showed that despite of increasing activity of enzyme the structure of yeast cell walls changed and hollowed in 100MPa pressure. The enzymatic activity and CFU (1log.) significantly decreased in 125 and 150 MPa. Inactivation of yeasts and decreasing the enzymatic activity can be due to morphological changes of yeast cells by induced high pressure. The images of scanning electron microscope (SEM) after one month pressurization and keeping in 4C° showed that all of treated yeast cells were destroyed.