OSCILLATORY HIGH HYDROSTATIC-PRESSURE INACTIVATION OF ZYGOSACCHAROMYCES-BAILII

Zygosaccharomyces bailii inactivation was evaluated in oscillatory hig h hydrostatic pressure (HHP) treatments at sublethal pressures (207, 2 41, or 276 MPa) and compared with continuous HHP treatments in laborat ory model systems with a water activity (a(w)) of 0.98 and pH 3.5. The yeast was inoculated into laboratory model systems and subjected to H HP in sterile bags. Two HHP treatments were conducted: continuous (hol ding times of 5, 10, 15, 20, 30, 60, or 90 min) and oscillatory (two, three, or four cycles with holding times of 5 min and two cycles with holding times of 10 min). Oscillatory pressure treatments increased th e effectiveness of HHP processing. For equal holding times, Z. bailii counts decreased as the number of cycles increased. Holding times of 2 0 min in HHP oscillatory treatments at 276 MPa assured inactivation (< 10 CFU/ml) of Z. bailii initial inoculum. Oscillatory pressurization c ould be useful to decrease Z. bailii inactivation time.