Pulsed high pressure treatment for the inactivation of Saccharomyces cerevisiae: The effect of process parameters

This paper aims to investigate the effect of main processing variables on the inactivation rates of Saccharomyces cerevisiae cells suspended in commercial fruit juices and processed in pulsed high pressure treatments. The investigated variables were: pressure level, number of pressurization cycles, pulse duration and ramp rate. According to our experimental results, the efficiency of pulsed high pressure processes depends on the combination of pulse holding time and number of pulses. Pulsed high pressure is more effective than isostatic pressure, provided that the pulse holding time is higher than a threshold value. Moreover, no additive effect of the pulses could be detected, being the lethality of the single pulses reduced when increasing the number of pulse and the ramp rate. These findings are confirmed at different pressure levels with all processing media utilized. If several pressurization cycles with a defined number of pulses are applied, the faster the compression rate the lower is the final inactivation level achieved.