High pressure inactivation kinetics of Saccharomyces cerevisiae ascospores in orange and apple juices

High pressure inactivation kinetics (D and z values) of Saccharomyces cerevisiae ascospores were determined in fruit juices and a model juice buffer at pH 3.5 to 5.0. Approximately 0.5 to 1.0 x 10(6) ascospores/mL were pressurized at 300 to 500 MPa in juice or buffer. D-values ranged from 8 sec to 10.8 min at 500 and 300 MPa, respectively. The range for z-values was 115 to 121 MPa. No differences (P greater than or equal to 0.05) in D (at constant pressure) or z-values among buffers or juices at any pH were determined, indicating little influence of pH in this range and absence of protective or detrimental effects of juice constituents.