Blue Light for Inactivation of Meatborne Pathogens and Maintaining the Freshness of Beef

Beef is rich in various nutrients but easily spoils due to bacterial contamination; thus, a bactericidal method is needed to inactivate meatborne pathogens while maintaining the freshness of beef. The present study was conducted to investigate for the first time the bactericidal effect of blue light (BL) at 415 nm against four meatborne pathogens (methicillin-resistant Staphylococcus aureus, Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes) both in vitro and inoculated onto the surface of fresh beef. The populations of the four pathogens on the nonirradiated control beef did not change significantly (P>0.05), whereas a dose-dependent inactivation effect was found for BL-treated beef both in vitro and in vivo. On the beef cuts, BL at 109.44 J/cm(2) inactivated 90% of inoculated cells of the tested strains (P<0.05), and this inactivation effect was sustained during 7 days of cold storage. Insignificant changes in lipid oxidation rate, water holding capacity, and cooking loss were found during storage between the control beef and the beef irradiated at 109.44 J/cm(2) at the same time. BL had a minor and nonsignificant effect on surface color and free amino acid concentrations. The pH of the treated beef increased more slowly (P<0.05) than did that of untreated beef. These results suggest that BL could be a novel bactericide and could help maintain the freshness of beef.