The use of gaseous ozone and gas packaging to control populations of Salmonella infantis and Pseudomonas aeruginosa on the skin of chicken portions

Chilled breasts of chicken were inoculated with Salmonella infantis or Pseudomonas aeruginosa and then given one of the following treatments: (i) exposure to gaseous ozone (>2000 ppm for up to 30 min); (ii) storage under 70% CO2:30% N2; and (iii) exposure to gaseous ozone (>2000 ppm for 15 min) followed by storage under 70% CO2:30% N2; all storage at 7 °C. Gaseous ozone reduced the counts of salmonellae by 97% and pseudomonads by 95%, but indigenous coliforms were unaffected. Under the modified atmosphere, the cell count of S. infantis was reduced by 72% following initial exposure and then stabilised, coliforms grew, but Ps. aeruginosa behaved like S. infantis--initial reduction (58%) followed by stability. Exposure to gaseous ozone followed by gas packaging allowed survival of S. infantis, Ps. aeruginosa and coliforms over 9 days at 7 °C, but there was no evidence of any sensory deterioration. It is proposed that the latter treatment could, in a modified form perhaps, be used to reduce the contamination of chicken carcasses with salmonellae and improve their shelf-life.