Regulating the permeability of poly(lactic acid)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) composite films for...

The gas permeability of packaging films significantly impacts the micro-environment and postharvest quality of fruits and vegetables. By regulating gas permeability to regulate the internal atmospheric composition of packaging, this method modulates the respiratory intensity and physiological metabolism of fruits and vegetables, thereby extending their postharvest shelf life. In this study, different proportions of Poly(lactic acid) (PLA)/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) composite films were prepared using the melt blending method, aiming to optimize the packaging microenvironment by adjusting the gas permeability of the films. The results indicate that the oxygen transmission rate of the composite film at a PLA/P34HB ratio of 20:80 was measured at 628.65 ± 7.2 cm³·m^-2·24 h^-1·0.1 MPa, which was 90.98 % higher than that of the PLA film. The Pearson heatmap further confirmed that the permeability of the composite film had a significant impact on the preservation effect of peaches, while the influence on mechanical properties was not significant. This finding was corroborated by preservation experiments using films of different compositions, which demonstrated that the PLA20:80P34HB composite film performed the best. Specifically, it effectively slowed the loss of free water, thereby maintaining moisture content, total soluble solids content, and weight, ultimately extending the shelf life by 66.67 %.