INFLUENCE OF PRESSURIZED CARBON-DIOXIDE ON THE THERMAL INACTIVATION OF BACTERIAL AND FUNGAL SPORES

The antimicrobial potential of CO2 applied under 5 MPa pressure during heat treatment was investigated against Bacillus subtilis spores, Bys sochlamys fulva ascospores and Aspergillus niger conidia. The rates of thermal inactivation were increased in the presence of pressurized CO 2 when treatment was carried out at a temperature higher than a thresh old value depending on the tested microorganism (80 degrees C for B. s ubtilis and B. fulva, 50 degrees C for A, niger). The antimicrobial ef fectiveness of CO2 varied with the microorganisms, the temperature and the a(w) of the suspension medium. However, the increase in the destr uction rate was relatively more extensive when the temperature was sub lethal or low lethal. At elevated lethal temperatures, the antimicrobi al effect of pressurized CO2 disappeared. Moreover, a low a(w) antagon ized the lethal effect of CO2 under pressure. (C) 1998 Academic Press Limited.