Construction and Performance Evaluation of Zein/PVDF Electrospun Nanofiber Membranes as Functional Carriers for Food Packaging

This study aimed to systematically evaluate the effects of the Zein/poly(vinylidene fluoride) (PVDF) blend ratio on the formation, structure, and performance of electrospun nanofiber membranes and to further assess the feasibility of incorporating bromothymol blue (BTB) into the optimized matrix as a pH-responsive functional component for intelligent food-packaging applications. Increasing PVDF content reduced the conductivity but increased the viscosity of the spinning solutions, and all formulations exhibited shear-thinning behavior. Pure Zein failed to form continuous fibers, whereas PVDF incorporation promoted uniform fibrous networks, with average fiber diameters increasing from 113.02 ± 27.06 nm to 530.68 ± 113.33 nm. FTIR and TGA/DTG analyses confirmed the coexistence of Zein and PVDF and the improved thermal stability associated with increasing PVDF content. Surface hydrophobicity and water resistance increased with PVDF content, whereas water vapor permeability (WVP) and water solubility (WS) increased with the Zein proportion. Considering spinnability, morphology, mechanical behavior, barrier performance, and water stability, the Zein/PVDF = 5:5 formulation provided a comparatively balanced performance and was selected as the functional carrier matrix. Incorporation of BTB into this matrix produced a distinct pH-responsive color change, and the color difference (ΔE) showed a strong correlation with shrimp pH during storage (R2 = 0.997), demonstrating the feasibility of the optimized membrane as a freshness-responsive functional carrier.