Effects of Chitosan Coatings on Controlling Listeria monocytogenes and Methicillin-Resistant Staphylococcus aureus in Beef and Mutton Cuts

Ruminant meat is considered to be a potent vehicle of foodborne pathogen transmission. Edible coatings are considered to be promising for enhancing meat safety. Here, edible chitosan membranes were applied to whole cuts of beef and mutton to test the survival of the pathogenic bacteria Listeria monocytogenes and methicillin-resistant Staphylococcus aureus. Meat pieces weighing approximately 200 g were inoculated with a cocktail of three S. aureus isolates or four L. monocytogenes isolates (6.00 log10CFU/g). The meat pieces were encased in a chitosan coating formed by immersion and incubated aerobically or vacuum-packaged in LDPE/PA/LDPE bags for up to 21 days. A decrease in both S. aureus (x = −1.95 log10CFU/g, standard error = 0.23 log10CFU/g) and L. monocytogenes counts (x = −1.07 log10CFU/g, standard error = 0.26 log10CFU/g) was observed. No significant differences were observed between L. monocytogenes-spiked beef and mutton pieces; statistically higher S. aureus counts were observed in mutton versus beef under similar treatments. Aerobic storage of meat pieces inoculated with L. monocytogenes enhanced the antibacterial effects of chitosan—a trend that was not observed in meat pieces inoculated with S. aureus. According to the results, edible chitosan membranes were effective in controlling the growth of S. aureus and L. monocytogenes.