Multifunctional pectin-based films containing schiff base triggered by pH microenvironment for freshness monitoring and preservation of fresh-cut papayas

Smart packaging materials display prospect to delay the deterioration of fresh agricultural products. In this study, pectin-based composite films were prepared with synthesized Schiff base compounds (GS) by gamma-aminobutyric acid (GABA) and syringaldehyde (SA). The scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) showed the cross-linking structures and good compatibility between GS and pectin in the composite films. The films incorporating GS had excellent texture density, water resistance, shielding ability of UV light and partial visible light, as well the ABTS and DPPH radical scavenging activity achieved 90.19% and 85.37%, respectively. The films displayed inhibition of E. coli , S. aureus , and B. cinerea , and were sensitive to color changes with different pH conditions. The GSP films monitored the freshness of fresh-cut papayas with color changes and effectively delayed the ripening of papaya. Therefore, the intelligent and active films triggered by pH microenvironment showed potential application in fruit preservation as packaging materials.