Factors affecting growth of foodborne pathogens on minimally processed apples

Escherichia coli O157:H7, Salmonella and Listeria innocua increased by more than 2 log10 units over a 24 h period on fresh-cut ‘Golden Delicious’ apple plugs stored at 25 and 20 °C. L. innocua reached the same final population level at 10 °C meanwhile E. coli and Salmonella only increased 1.3 log10 units after 6 days. Only L. innocua was able to grow at 5 °C. No significant differences were observed between the growth of foodborne pathogens on fresh-cut ‘Golden Delicious’, ‘Granny Smith’ and ‘Shampion’ apples stored at 25 and 5 °C. The treatment of ‘Golden Delicious’ and ‘Granny Smith’ apple plugs with the antioxidants, ascorbic acid (2%) and NatureSeal® (6%), did not affect pathogen growth. The effect of passive modified atmosphere packaging (MAP) on the growth of E. coli, Salmonella and L. innocua on ‘Golden Delicious’ apple slices was also tested. There were no significant differences in growth of pathogens in MAP conditions compared with air packaging of ‘Golden Delicious’ apple plugs, but the growth of mesophilic and psychrotrophic microorganisms was inhibited. These results highlight the importance of avoiding contamination of fresh-cut fruit with foodborne pathogens and the maintenance of the cold chain during storage until consumption.