Comparison of Nonthermal Decontamination Methods to Improve the Safety for Raw Beef Consumption

Abstract

The object of this study was to examine nonthermal treatments to reduce foodborne pathogens in beef that is consumed raw. Foodborne illness pathogens (Escherichia coli, Salmonella, Staphylococcus aureus, and Listeria monocytogenes) were inoculated in the raw beef eye round. Death rates of foodborne illness pathogens were evaluated by nonthermal decontamination methods: high pressure processing (HPP) at 500 MPa for 2, 5, and 7 min; UV light-emitting diode (LED) radiation at 405 nm for 2, 6, and 24 h; hypochlorous acid water (HAW) at 100 ppm for 1, 3, and 5 min; 2.5% lactic acid (LA) for 1, 3, and 5 min; modified atmosphere packaging that replaced O2 to CO2 for 24 and 48 h with anaerogen (O2 levels were less than 1% and CO2 levels were 9 to 13%); and bio-gel application (BGA) for 24 and 48 h. For the bio-gel preparation, 5% sodium alginate was dissolved in 40 mL of glycerol and mixed with 0.2% CaCl2 dissolved in 60 mL of water, and this mixture was left at room temperature for solidification. Quality characteristics (color, pH, water activity, and texture) were measured after applying the practical nonthermal decontamination application. After HPP treatment for 7 min, inactivity rates were 4.4 to 6.7 Log CFU/g (100.0%) for E. coli, Salmonella, and L. monocytogenes and 1.7 Log CFU/g (98.0%) for S. aureus (P < 0.05). After treatment with UV LED for 24 h, reduced cell counts were 0.5 Log CFU/g (67.3%), 0.7 Log CFU/g (82.2%), and 0.3 Log CFU/g (47.1%) for E. coli, Salmonella, and S. aureus, respectively (P < 0.05), but no significant reduction of 0.0 Log CFU/g (4.3%) was observed for L. monocytogenes. When the beef was treated with HAW for 5 min, 0.6 Log CFU/g (73.3%) of E. coli, 0.5 Log CFU/g (66.2%) of Salmonella, 0.4 Log CFU/g (60.7%) of S. aureus, and 0.5 Log CFU/g (65.6%) of L. monocytogenes were inactivated. After the beef was treated with LA for 5 min, 1.8 Log CFU/g (98.5%) of E. coli, 3.0 Log CFU/g (99.9%) of Salmonella, 1.3 Log CFU/g (95.4%) of S. aureus, and 1.9 Log CFU/g (98.6%) of L. monocytogenes were inactivated. Modified atmosphere packaging for 48 h caused the inactivation of 0.3 Log CFU/g (51.8%) of E. coli and 0.1 Log CFU/g (19.2%) of Salmonella. After BGA treatment for 48 h, 0.3 Log CFU/g (55.2%) of E. coli and 0.4 Log CFU/g (58.7%) of Salmonella were significantly decreased (P < 0.05). HPP cooked the beef after 2 min of treatment. HAW and BGA changed the surface color of the beef, and LA reduced the pH of beef (P < 0.05). However, UV LED did not cause changes in the beef quality properties. These results indicates that UV LED can improve the food safety of raw beef without changes in beef quality.