LAUSR

The aim of this study was to investigate the synergistic effect of chitosan and bacteriocins against Escherichia coli and Salmonella in media and in lean beef. The inhibitory effects of chitosan and bacteriocins against E. coli AW1.7 and S. enterica Typhimurium in media were determined by a critical dilution assay. The efficacy a bacteriocin-producing strain of Carnobacterium maltaromaticum and high molecular weight chitosan (HMWC) in inactivation of E. coli AW1.7 and S. Typhimurium was evaluated on beef. Current interventions applied in the beef industry, steaming coupled with lactic acid, were used as reference. HMWC demonstrated higher antibacterial activity than water soluble chitosan (WSC) or chitosan oligosaccharides (COS) in media, and the addition of partially purified bacteriocins from C. maltaromaticum UAL307 increased the activity of the chitosan in vitro. The hurdle combinations associated with HMWC inactivated E. coli AW1.7 and S. enterica Typhimurium more effectively on lean beef when compared to steam or steam coupled with lactic acid. When used on beef, addition of bacteriocins and chitosan did not increase the antibacterial efficacy. Cell counts of S. enterica were further reduced during storage in presence of C. maltaromaticum and chitosan; however, this decrease was not dependent on bacteriocin production. In conclusion, addition of chitosan alone or in combination with C. maltaromaticum UAL 307 as protective culture significantly reduces cell counts of E. coli and Salmonella on beef. Results will be useful to improve pathogen intervention treatments in beef processing.