Development of novel poly(lactic acid) active multilayer composite films by incorporating catechol-functionalized layered clay into chitosan/poly(vinyl alcohol) coatings

Nowadays, there has been a marked increase in the use of biopolymer-based active packaging film, which can improve the shelf life of food. However, poly(lactic acid) (PLA) packaging suffers from poor gas barrier and antibacterial, UV barrier properties. To address this issue, we applied coating technology to improve the active packaging functions of PLA film. In this study, inspired by super adhesion and versatility of catechol groups based on mussel bionics, catechol-functionalized layered clay (LDHs@QUE-Cu) was first synthesized through adsorption and complexation of natural active polyphenol quercetin (QUE) with copper ions on the surface of layered double hydroxides (LDHs). PLA active multilayer composite films were developed by incorporating LDHs@QUE-Cu (0.5-5 wt%) into chitosan (CS)/poly(vinyl alcohol) (PVA) coatings. With the addition of LDHs@QUE-Cu, the maximum antibacterial rate against Escherichia coli of PLA active multilayer composite films reached 87.8 %. Even compared with the control sample (PLA film coated by pure PVA), the oxygen transmission rate of PLA active multilayer composite films was still reduced by 77.5 %. Compared with PLA film, the UV absorption (at 280 nm) of PLA active multilayer composite films was increased by up to 39.8 %. Still, all films maintained good transparency (higher than 88.0 %) and mechanical properties. Therefore, the multilayer composite films obtained by waterborne multifunctional coatings on the surface of PLA film can be applied potentially in active food packaging application.

Automated summary

In recent years, there has been an increase in the use of biopolymer-based active packaging films to improve food shelf life. This study focuses on improving the active packaging functions of poly(lactic acid) (PLA) films through coating technology. The researchers developed multilayer composite films with antibacterial and UV barrier properties by incorporating catechol-functionalized layered clay into chitosan/poly(vinyl alcohol) coatings. The results showed significant improvements in antibacterial rate, oxygen transmission rate reduction, and UV absorption.