Antimicrobial effects of pressurised carbon dioxide onBrochothrix thermosphacta in broth and foods

Antimicrobial effects of high-pressure CO2 on Brochothrix thermosphacta were investigated in a batch system. Inactivation rates increased with increasing pressure, temperature and exposure time. B thermosphacta suspended in physiological saline was completely inactivated under 6.05, 3.02 and 1.51 MPaCO2 treatment at 35 °C after 10, 25 and 50 min respectively. Two phases were observed in the survival curves. The earlier stage was characterised by a slow rate of decrease in the number of B thermosphacta, which increased sharply at the later stage. B thermosphacta suspended in brain heart infusion broth was completely inactivated under 6.05 MPaCO2 treatment after 80, 50 and 30 min at 25, 35 and 45 °C respectively. About 6.90 and 5.93 log cycles of B thermosphacta were reduced under 6.05 MPaCO2 pressure at 45 °C in whole and skimmed milk respectively. The sterilisation effects of 6.05 MPaCO2 pressure at 45 °C on both B thermosphacta and aerobic plate count were observed after 150 and 120 min respectively in skinned meat.