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

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 degrees 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 x 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. (C) 2015 Elsevier B.V. All rights reserved.