Neem (Azadirachta indica A. Juss) Oil: A Natural Preservative to Control Meat Spoilage

Plant-derived extracts (PDEs) are a source of biologically-active substances having antimicrobial properties. The aim of this study was to evaluate the potential of neem oil (NO) as a preservative of fresh retail meat. The antibacterial activity of NO against Carnobacterium maltaromaticum, Brochothrix thermosphacta, Escherichia coli, Pseudomonas fluorescens, Lactobacillus curvatus and L. sakei was assessed in a broth model system. The bacterial growth inhibition zone (mm) ranged from 18.83 +/- 1.18 to 30.00 +/- 1.00, as was found by a disc diffusion test with 100 mu L NO. The bacterial percent growth reduction ranged from 30.81 +/- 2.08 to 99.70 +/- 1.53 in the broth microdilution method at different NO concentrations (1:10 to 1:100,000). Viable bacterial cells were detected in experimentally-contaminated meat up to the second day after NO treatment (100 mu L NO per 10 g meat), except for C. maltaromaticum, which was detected up to the sixth day by PCR and nested PCR with propidium monoazide (PMA (TM)) dye. In comparison to the previously published results, C. maltaromaticum, E. coli, L. curvatus and L. sakei appeared more susceptible to NO compared to neem cake extract (NCE) by using a broth model system.