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

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.