Inactivation of food poisoning bacteria and Geobacillus stearothermophilus spores by high pressure carbon dioxide treatment

Inactivation of the vegetative foodborne pathogens by high pressure carbon dioxide treatment (HPCT) was investigated. Pseudomonas aeruginosa IFO3445, Aeromonas hydrophila IFO13286, Salmonella enteritidis JCM3313, Salmonella typhimurium IID1000, Yersinia enterocolitica JCM1677, Escherichia coli O157:H7 ATCC35150, E. coli O157:H7 ATCC43889, Staphylococcus aureus FDA209P and Listeria monocytogenes 1/2a were used in this study. In all cases, HPCT at 35°C, 10MPa for 1min reduced initial numbers by approximately 6logs. In addition HPCT inactivation of 9 pathogenic strains of Bacillus cereus (mixture of spores and vegetative cells) was investigated. HPCT at 75°C, 10MPa for 120min resulted in significant inactivation in all the strains. The effect of HPCT (30MPa at 95°C for up to 120min) on the inactivation of Geobacillus stearothermophilus spores in the presence of sodium chloride (3% and 6% w/v), glucose (6% and 12% w/v) and ethanol (10% and 20% v/v) was also studied. Both sodium chloride and glucose had a protective effect and the level of inactivation was reduced. The effect was in proportion to the solute concentration. However, 10% and 20% ethanol did not significantly affect the level of inactivation.