Active bilayer films based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and proteins containing rutin and carvacrol encapsulated in Pickering emulsion

Abstract

One strategy to improve the performance of protein-based films is the development of bilayer structures with complementary properties. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable biosynthetic polyester that exhibits complementary barrier properties to those of protein-based films. The objective of this study was to obtain and characterize active bilayer films composed of PHBV/gelatin (GE) or sodium caseinate (SC) monolayers films that incorporate rutin and carvacrol in Pickering emulsion (PE). The bilayers were produced by thermocompression. In general, the incorporation of PE in the monolayer films decreased the oxygen permeability (OP) by 27.6 % for GE and 5 % for SC, respectively, which was attributed to an increase in the film tortuosity and provided the films with remarkable antioxidant activity, especially in the less polar simulant. Furthermore, in gelatin films the incorporation of PE also provided them with greater mechanical resistance (increase 29 %) that suggested the presence of significant phenolics-gelatin interactions. Laminating the protein-based films with a PHBV layer conferred the bilayer films with significantly improved water and oxygen barrier properties (0.15 g/m·h·kPa and 70 cm³/m·h·kPa, respectively) and mechanical performance intermediate between those of the respective monolayer films. The PE-loaded bilayer films exhibited enhanced oxygen barrier capacity with a reduction of OP of 16–38 % but with reduced antioxidant activity by ∼19 % compared to the monolayer films. Furthermore, a mild antimicrobial activity against E. coli was observed in the PE-loaded bilayer films. Given this, the bilayer structures demonstrate potential for extending the shelf life of foods and offer a sustainable alternative for active food packaging.