Electrospun Gelatin/Chitosan Coatings on PLA Films: Effects of Processing Parameters and Incorporated Phenolic Compounds on Network Morphology and Film’s Physical and Functional Properties

This study developed surface-functionalized polylactic acid (PLA) films by depositing electrospun gelatin/chitosan (GE/CH) nanofibrous coatings formulated with and without bioactive phenolic compounds (curcumin and anthocyanin). Evaluating various polymer blending ratios and operational parameters revealed that a GE:CH ratio of 7:3 (v/v), processed at an applied voltage of 25 kV and a collector speed of 300 rpm, provided the most stable electrospinning behavior among those tested, yielding a uniform nanoscale fibrillar network. The deposition of this selected GE/CH layer onto the PLA substrate significantly improved the composite bilayer film’s tensile strength and oxygen barrier properties, although it increased macroscopic opacity. Furthermore, active coatings containing 0.25% and 0.50% (w/w) curcumin or anthocyanin were successfully processed. This 0.50% level was the maximum concentration quantitatively evaluated in the present study, as preliminary observations suggested poorer processability at higher concentrations, which induced premature gelation and needle clogging. While interactions (mostly non-covalent physical interactions) associated with the phenolic compounds synergistically reinforced the mechanical rigidity and reduced the water vapor permeability of the bilayer films, the macroscopic bioactive functionality was limited. The low loading concentrations, coupled with severe optical masking and restricted aqueous extraction, resulted in moderate antioxidant activity (10.31–30.46% DPPH radical inhibition) and no visually detectable halochromic (pH-responsive) color changes. Overall, these findings highlight a significant functional trade-off in the design of active coatings, where structural and mass transport barrier enhancements are achieved, but macroscopic bioactive functionality is constrained, underscoring the necessity for advanced encapsulation strategies in future developments.