Responsive packaging based on imine-chitosan films for extending the shelf-life of refrigerated fresh-cut pineapple

Reversible imine chemistry has been employed to stabilize antimicrobial liquid volatiles trans-2-hexenal (HX) and salicylaldehyde (SL) to the surface of chitosan films. The reactivity of both aldehydes to amine groups of chitosan was high and the synthesis of imine bonds was assessed by ATR-FTIR. The hydrolysis of the bonds and the release of the aldehydes depended on the pH of the medium. Films exerted in vitro microbiocidal effect against E. coli, S. cerevisae and pineapple wild yeast when were immersed at pH 3.6. Finally, films were incorporated in the double-bottom of plastic containers filled with fresh-cut pineapple maintained at 4 °C for 18 days. Juice leakage from pineapple pieces triggered the release of aldehydes to the headspace of the package. Both aldehydes extended microbiological shelf-life of fruit and slowed down browning. SL increased juice leakage from fruit and affected firmness negatively.