Survival of foodborne pathogens on commercially packed table grapes under simulated refrigerated transit conditions

We examined the survival of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica Thompson inoculated on commercially packed table grapes under simulated refrigerated transit conditions (1.1 ± 0.5 °C; 90% RH). Grapes were placed in perforated polyethylene cluster bags, within a commercial expanded polystyrene box equipped with either a SO₂-generating pad; a perforated polyethylene box liner; a SO₂-generating pad and a box liner; or none of them. L. monocytogenes was most sensitive to SO₂-generating pad. SO₂-generating pad or SO₂-generating pad with box liner inactivated this pathogen completely on day 12 following the inoculation. S. enterica Thompson displayed a similar cold sensitivity as L. monocytogenes, but was more resistant to SO₂-generating pad than L. monocytogenes. While SO₂-generating pad eliminated S. enterica Thompson on day 20, a combination of box liner with SO₂-generating pad inactivated this pathogen completely on day 13. E. coli O157:H7 had the highest tolerance to transit temperature and to SO₂-generating pad; SO₂-generating pad inactivated this pathogen completely on Day 20. Our data suggest that use of SO₂-generating pad combined with box liner is effective in reducing foodborne pathogens L. monocytogenes and S. enterica Thompson, while the use of SO₂-generating pad alone was more effective on E. coli O157:H7.