Green beans preservation by combination of a modified chitosan based-coating containing nanoemulsion of mandarin essential oil with high pressure or pulsed light processing

Abstract The combination of an antimicrobial edible coating with other non-thermal treatments, comprising high hydrostatic pressure (HHP) or pulsed light (PL), was assessed against Listeria innocua , inoculated on green bean samples, evaluating also the impact on product color and firmness during 14 days refrigerated storage at 4 °C. The coating formulation consisted of modified chitosan containing a nanoemulsion of mandarin essential oil. Non-thermal treatments conditions were determined in preliminary inactivation tests against L. innocua inoculated on coated green beans, which showed that 400 MPa and 5 min for HHP, and 1.2 × 10 5  J/m 2 per bean side for PL, were able to cause a reduction in L. innocua population of about 4 and 2 Log cycles, respectively. The combination of the coating application with HHP resulted as the most promising approach, causing a significant reduction of L. innocua over the entire storage period, owing to the development of a significant synergism of antimicrobial effects; however, it also had a strong impact on green beans firmness. In contrast, the combination of the coating application with PL exhibited a slight antagonistic effect, and had a slight detrimental impact on color properties.