Development and characterisation of polylactic acid–gliadin bilayer/trilayer films as carriers of thymol

Abstract

Summary Biodegradable food packaging promises a more sustainable future. Poly(lactic acid) (PLA) is a promising alternative for petroleum‐derived polymers. However, PLA films suffer from poor barrier properties compared with petroleum‐derived ones. To address this issue, we designed bilayer and sandwich‐architectured trilayer films based on PLA and gliadin. We reported firstly the direct formation of PLA–gliadin bilayer/trilayer films without surface modification on PLA film. The films were compact and uniform, and double/triple layers were combined firmly, preventing delamination. This strategy enhanced mechanical resistance, ductility and moisture barrier of gliadin films and concomitantly enhanced the oxygen barrier for PLA films. Thymol loadings endowed bilayer/trilayer films with antimicrobial activity and antioxidant activity. The antimicrobial activity of the films depended on film types, and gliadin layer presented larger inhibition zone than PLA layer, hinting that the films possessed directional releasing role. This study opens a promising route to fabricate bilayer/trilayer architecture helping to create synergism of the biopolymers.

Development of Chitosan and Polycaprolactone Based Trilayer Biocomposite Films for Food Packaging Applications

“…The authors indicated a highly confined release for gallic acid due to the presence of top polylactic acid layers. Similar to our study, the external layers acted as a barrier to the release of gallic acid [46] found a slower release of thymol from polylactic acid and gliadin based trilayer films, which might be due to the barrier effect of the polylactic acid layer.…”

“…Similarly, Zhu et al [46] found a slower release of thymol from polylactic acid and gliadin based trilayer films, which might be due to the barrier effect of the polylactic acid layer.…”

“…Besides, Quiles-Carrillo et al [45] found a reduction in transmittance of multilayer polylactic acid films, including internal layers with gallic acid, probably due to the thermal post-treatment at 150°C. Zhu et al [46] also observed significantly lower transmittance values for trilayer films of polylactic acid and gliadin. Film samples have high lightness values (>90), whereas only PCL/CHG/PCL and PCL/CHG5N/PCL films displayed lower lightness values when compared to PCL/CH/PCL film due to the more impenetrable matrix (p>0.05) ( Table 3).…”

Biodegradable Antimicrobial Food Packaging: Trends and Perspectives

“…Another way to improve the WVP is presented by Zhu J.Y. et al, who have obtained bi and tri-layer films from PLA and gliadin, without surface modification [ 158 ]. These films have a good mechanical resistance, do not exfoliate, and most important, the gliadin improves the barrier properties of the PLA toward oxygen, while the PLA improves the barrier properties of gliadin toward water vapor.…”

Optimising chitosan–pectin hydrogel beads containing combined garlic and holy basil essential oils and their application as antimicrobial inhibitor

“…Hydrogels are three-dimensional cross-linked polymer networks, which can absorb large amounts of water (Ahmed, 2015). These networks maintain their structure during the exchange of water and provide controlled release via pores in the polymer network (Zhu et al, 2018). Hydrogels based on polysaccharides, like chitosan and pectin, have been increasingly utilised in various fields (Kwiecie n & Kwiecie n, 2018).…”