Survival of Pathogens on Modified-Atmosphere-Packaged Shredded Carrot and Cabbage

The populations changes of Staphylococcus aureus , Bacillus cereus , Listeria innocua , Salmonella typhimurium and Clostridium perfringens inoculated separately onto modified-atmosphere-packaged fresh shredded carrot and cabbage was investigated. Shredded carrot and cabbage (25-g amounts) was packaged in polypropylene film (35 μm thick) and stored at 7°C. The modified atmosphere within the packs was produced naturally by respiration with levels of carbon dioxide reaching >25% and levels of oxygen falling to <1% following 8 days of storage. Populations of pathogens were enumerated by direct plating on selective media on the day of inoculation and 2, 4, 6, and 8 days postinoculation. The presence or absence of S. typhimurium was determined following preenrichment and selective enrichment steps: this species was found to be absent following 2 days of storage at 7°C. Statistically significant decreases (P < 0.05) in numbers of all other pathogens detected on day 0 and day 8 were observed. Pathogens were not detected on these vegetables in uninoculated packs.