Combined effect of N,O-carboxymethyl chitosan and oregano essential oil to extend shelf life and control Listeria monocytogenes in raw chicken meat fillets

The combined effect of 1 g/100 ml N,O-carboxymethyl chitosan (NOCC) and 1% oregano essential oil (OEO) dip for the control of Listeria monocytogenes and shelf life extension of chicken breast fillets was investigated. L monocytogenes was inoculated in chicken breast meat at 10(3) and 10(5) cfu/g. Samples were packaged aerobically and stored at 4 degrees C for a period up to 14 days. Results showed that total viable count (TVC) exceeded 7 log cfu/g after day 6 and 10 for control samples and samples treated with OEO respectively. Samples treated with either NOCC or OEO plus NOCC never reached 7 log cfu/g throughout storage. NOCC had a substantially stronger antimicrobial effect as compared to OEO. A 1.2 and 2.8 log cfu/g reduction in L. monocytogenes (low inoculum) in comparison to control samples was recorded for the OEO and NOCC treated samples respectively after 14 day of storage. Respective values for the high Listeria inoculum were 1.5 and 33 log cfu/g. Complete inhibition of L. monocytogenes was achieved for the combination OEO plus NOCC as early as day 2 and 4 of storage for the low and high inoculum samples respectively. (C) 2013 Elsevier Ltd. All rights reserved.