Responses of Pseudomonas fluorescens to combined high pressure/temperature treatments

A Pseudomonas fluorescens strain isolated from pork meat and inoculated in culture broth was subjected to high pressure (200 and 400 MPa/10 min) at 5, 20 and 35°C. Pressurization at 200 MPa/5°C reduced the bacterial growth by 5 log cycles, and this effect decreased as the pressurization temperature increased. At 400 MPa, P. fluorescens growth was inactivated. The counts of P. fluorescens treated at 200 MPa after day 1 of incubation at 20°C were higher than those obtained immediately after treatment; conversely, at 400 MPa, they were still below the detection threshold. After 8 and 16 days of incubation, counts of pressurized and non-pressurized bacteria were similar. Scanning electron microscopy showed that pressure-induced morphological changes were more pronounced at 400 MPa and that the effect of pressure was influenced by the treatment temperature. © Springer-Verlag 2002.This research was supported by the Comisión Interministerial de Ciencia y Tecnología (CICYT) under projects ALI 97–0759 and AGL2000–1497.Peer Reviewe