Development and characterization of antioxidant bilayer film based on poly lactic acid-bitter vetch (Vicia ervilia) seed protein incorporated with Pistacia terebinthus extract for active food packaging

This study focuses on designing an active bilayer food package film based on polylactic acid (PLA) and bitter vetch seed protein incorporated with Pistacia terebinthus extract (PTE). The effect of PTE on the physicochemical, barrier, structural, mechanical, and antioxidant properties of the active film was determined. Moisture content, water solubility, and water vapor permeability (WVP) of the active films indicated that the addition of PTE increased its suitability for food packaging. FE-SEM micrographs illustrated that the resulting films had a smooth and dense surface, describing a continuous network of protein molecules within the film structure. FTIR analysis displayed the physical interaction between PTE and the film polymer. XRD revealed an increase in the crystallinity of the active films. The resulting active film had a low migration rate (<7%) of phenolic compounds into fatty food simulant. Notably, the addition of PTE significantly (P ≤ 0.05) decreased the tensile strength and Young's modulus (from 15.13 and 315.98 MPa to 14.07 and 254.07 MPa, respectively). Concurrently, there was an increase in the elongation at break of the active films (from 23.19 to 75.60%), indicating higher flexibility compared to control films. Additionally, the incorporation of PTE improved the thermal properties of active films. The antioxidant capacity of the designed films was measured based on their DPPH radical scavenging activity, revealing that the antioxidant capacity of the control film increased from 44.65% to 59.72% in the active film containing 15% PTE. In conclusion, the prepared bilayer film can effectively be used as an active food package for sensitive foods to oxidation.