Efficiency of chitosan synergism with clove essential oil in the coating of intentionally contaminated Tambaqui fillets

The edible coating of chitosan with clove essential oil (CEO) was studied for its ability to reduce the microbial growth of pathogens (Escherichia coli O157:H7 CDCEDL933, Listeria monocytogenes CERELA, Salmonella Enteritidis ATCC13076, Staphylococcus aureus ATCC43300, and Pseudomonas aeruginosa ATCC27853) in Tambaqui fillets kept under refrigeration. In in vitro tests, chitosan showed higher antimicrobial activity against S. aureus and L. monocytogenes (MIC 0.5%), and CEO for L. monocytogenes (MIC 0.08%). Based on the antimicrobial activity of chitosan and CEO, Tambaqui fillets were subjected to different treatments, T1: chitosan 2%; T2: chitosan 2% + CEO 0.16%, and T3: chitosan 0.5% + CEO 0.08%, kept at 4 degrees C for 72 h. The chitosan coating, incorporated with CEO, inhibited microorganisms in Tambaqui fillets and enhanced coating efficiency (p < 0.05). It was most effective against L. monocytogenes and S. aureus at the lowest CEO concentration (0.08%). Chitosan coating in combination with CEO enhanced the antimicrobial effect of pathogens on Tambaqui fillets, increased their shelf life under refrigeration, and was more effective against Gram-positive pathogens than Gram-negative pathogens.