Apparatus for the simultaneous processing of mesophilic spores by heat-only and by high pressure and heat in a high pressure vessel to investigate synergistic spore inactivation

摘要

We sought to develop a paired sample container system that permits simultaneous processing of two samples in the same high pressure vessel, one pressurized and one protected by a pressure-resistant shell (heat-only), and subsequently compared the effect of pressure (600 MPa) on the inactivation of spores of Bacillus amyloliquefaciens and Clostridium sporogenes at high temperature. Reducing the compression rate to 200 MPa/min saw near-identical thermal profiles (R-2 0.990) delivered to paired samples, thereby facilitating a means to directly attribute increases in inactivation in pressurised samples to the synergistic effect of pressure and heat. At 115 degrees C (3.5 min hold time), inactivation of B. amyloliquefaciens spores was around 7 log(10) cfu/mL greater with pressure while the high pressure thermal (HPT) inactivation of C sporogenes spores was approximately 2 log(10) cfu/mL more than by heat alone after 1-2 min at 100 degrees C. Using this system we have demonstrated unequivocally that high pressure acts synergistically with heat to inactivate spores of B. amyloliquefaciens and C sporogenes.