Effects of Citrox and chitosan on the survival of Escherichia coli O157:H7 and Salmonella enterica in vacuum-packaged turkey meat.

In this study, we examined the antimicrobial effects of citrus extract (Citrox(®)) and chitosan on lactic acid bacteria (LAB) and the pathogens Escherichia coli O157:H7 and Salmonella enterica on turkey meat during storage under vacuum packaging (VP) at 4 and 10 °C. We also examined the effects of Citrox and chitosan on pathogen contamination in tryptic soy broth (TSB). Chitosan alone or in combination with Citrox inhibited the growth of endogenous LAB in turkey meat, whereas citrus extract did not cause a major reduction in bacterial density. Citrus extract combined with chitosan yielded the lowest mesophilic total viable counts (TVCs), irrespective of temperature, showing major declines in all treated turkey samples from days 0-21 of storage. The shelf-lives of untreated, Citrox-treated, and chitosan and Citrox/chitosan-treated samples (as determined by TVC and sensory data) were 13, 17, and >21 days, respectively, at 4 °C for VP turkey. The addition of Citrox was more effective against S. enterica than E. coli in turkey, causing reductions of >0.5 and 2 log cfu/g at 4 and 10 °C, respectively, after 21 days of storage. Interestingly, the addition of chitosan had a significant inhibitory effect on E. coli at 4 °C and S. enterica at 10 °C as compared with the control (inoculated samples) resulting in dramatic reductions in E. coli (2 log) and S. enterica (5 log) cell counts on day 21. Of all the treatments examined, citrus extract in combination with chitosan showed an additive inhibitory effect against both pathogens, reducing E. coli and S. enterica populations, by approximately 2.7 or 4.5 and 2.2 or 5.6 log cfu/g, respectively, at 4 and 10 °C on day 21 of storage.