Improving the active food packaging function of poly(lactic acid) film coated by poly(vinyl alcohol) based on proanthocyanidin functionalized layered clay

In this paper, natural plant polyphenol-proanthocyanidin (PAC) and layered clay-layered double hydroxides (LDHs) were firstly introduced into poly(vinyl alcohol) (PVA) based coatings to construct PAC/PVA and PAC functionalized LDHs (LDHs@PAC-Cu)/PVA dual active coatings, and further successively coated on the surface of PLA base films to develop PLA active films. The results showed that PAC and copper ions were successfully loading on the LDHs surface through adsorption and complexation. After a certain amount (>= 3 wt%) of LDHs@PAC-Cu was added, active packaging functions and gas barrier properties of PLA active films were improved markedly. When 5 wt% LDHs@PAC-Cu was added, antioxidant and antibacterial properties of PLA active films reached 84.31% and 95.5%, oxygen and water vapor transmission rate decreased by 99.4% and 62.6% compared with PLA base film, and the shelf life of pasteurized milk was extended from 60 h to 96 h. Active substances release test indicated that LDHs@PAC-Cu could not only delay the release of active substances in the early stage, but also supplement the release of active substances in the later stage, thus extending the shelf life of food more effectively. Therefore, PLA active films have good application potential in the field of active food packaging.

Automated summary

In this study, natural plant polyphenol-proanthocyanidin (PAC) and layered clay-layered double hydroxides (LDHs) were incorporated into poly(vinyl alcohol) (PVA) coatings to create PAC/PVA and PAC functionalized LDHs (LDHs@PAC-Cu)/PVA dual active coatings, which were then applied to PLA base films to develop PLA active films. The results demonstrated that the addition of LDHs@PAC-Cu significantly enhanced the active packaging functions and gas barrier properties of PLA films. Furthermore, the antioxidant and antibacterial properties of PLA films reached high levels, and the shelf life of pasteurized milk was extended. Active substances release test showed that LDHs@PAC-Cu not only delayed the release of active substances in the early stage, but also supplemented their release in the later stage, effectively prolonging the shelf life of food. Therefore, PLA active films have great potential in active food packaging.