Tannic acid/polylactic acid-grafted maleic anhydride/polylactic acid active packaging for peach preservation

The development of high-performance active packaging systems requires both high loading capacity of active substances and retention of favorable overall properties. However, poor compatibility between tannic acid (TA) and polylactic acid (PLA) limits active loading and degrades film performance.

This study investigated the role of polylactic acid-grafted maleic anhydride (PLA-g-MAH) as a compatibilizer to enhance the incorporation of TA into PLA. The performance of the prepared composite films was evaluated together with their efficacy in peach preservation. The results demonstrated that the addition of PLA-g-MAH enabled a 50% higher TA loading in the films. Compared with uncompatibilized polylactic acid films with 6% tannic acid (PLA-6%TA), the compatibilized matrix films with 6% tannic acid (MPLA-6%TA) exhibited improved tensile strength (from 17.29 to 27.70 MPa) and oxygen barrier properties (oxygen permeability decreased from 550.74 to 393.34 cm³ m^-2 24 h^-1 0.1 MPa^-1), indicating superior application performance. The compatibilized matrix films with 9% tannic acid (MPLA-9%TA) films exhibited notable antioxidant activity with a 96.60% 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging rate and effective antibacterial capability against Staphylococcus aureus, with an inhibition rate of 99.83%. These advantages extended the peach shelf life by 200% (from 4 days to 12 days), effectively delaying quality deterioration such as weight loss, hardness reduction, total viable count (TVC), malondialdehyde (MDA) accumulation, as well as modulating antioxidant enzyme activities.

This work provides a strategy using PLA-g-MAH to improve the blending between PLA and TA, enabling high active loading with improved mechanical and oxygen barrier properties compared with the blend without compatibilizer. The MPLA-TA composite films show strong potential for broadening PLA-based materials in active food packaging applications, extending the shelf life of perishable fruits such as peaches. © 2026 Society of Chemical Industry.