Antimicrobial Effect of Chitosan Coating Containing An Essential Oil Against Salmonella enteritidis On Fresh-Cut Apples

Processing involved in preparing fresh-cut products increases the risk of bacterial growth and contamination by breaking the natural exterior barrier of the produce.  Chitosan and essential oils are widely used as antimicrobial agent against a wide range of target organisms. The objective of this study was to assess the antimicrobial effect of chitosan (CH) coating containing rosemary essential oil (RO) against Salmonella enteritidis on fresh-cut apples. S. enteritidis was inoculated onto the surface of fresh-cut apples to give an initial inoculation of approximately 6.3 log CFU/g.  Apple samples were dipped in solutions of glacial acetic acid (AA, pH 5.6), 1% CH, 0.1% RO, and mixture of 1% CH and 0.1% RO (CH+RO), respectively.  Inoculated samples without any treatment were used as control.  All samples were stored at 5°C for 15 days.  S. enteritidis counts of CH and CH+RO treated samples were reduced by 3.0 to 3.5 logs on day 0 and did not grow back throughout the study, while S. enteritidis counts of control, AA and RO treated samples were reduced by 2.0 to 3.0 logs after 15 day storage.  Total plate counts of CH and CH+RO treated samples were reduced by 2.0 logs on day 0 and showed additional 1.5 to 2.0 log reduction after 15 day storage, whereas total plate counts of control, AA and RO treated samples showed 1.0 to 1.5 log reduction after 15 day storage.  The results of this study indicate that chitosan coating has a potential to inhibit the growth of S. enteritidis in fresh-cut apples.