Bacterial Effect of High Pressure CO Treatment on Foods Spiked with Listeria or Salmonella.

Studies were carried out to assess the use of high pressure CO, treatment for controlling pathogenic microorganisms in model food systems. Listeria monocytogenes suspended in distilled water was completely killed after CO treatment at 6.18 MPa (61.2 atm) and 35°C for 2 h. Contrary to CO treatment, the use of N at these experimental conditions failed to exert bactericidal effect. High pressure CO treatment at 13.7 MPa (136.1 atm) and 35°C for 2 h was shown to effectively kill Salmonella in spiked chicken meat (>95%) and egg yolk (> 100%), and kill Listeria in spiked shrimp (> 99%), orange juice (> 99%), and egg yolk (> 99.4%). Such treatment was, however, less effective in killing Salmonella in a whole egg- Salmonella mixture. Furthermore, this treatment caused a twofold increase in bacterial numbers in a whole egg- Listeria mixture. N gas under similar experimental conditions did not kill the spiked bacteria in these four food systems. High pressure CO treatment technique could possibly be applied to reduce microbial load in some food systems.