Maillard reaction altering the properties of pullulan/fish skin gelatin based electrospun nanofibers: structure, physicochemical, mechanical characteristics and antibacterial activity

In this study, novel pullulan (PUL)/fish skin gelatin (FSG) electrospun nanofibers were cross-linked via Maillard reaction (MR) to enhance their functional properties for food packaging applications. Crosslinking index and X-ray photoelectron spectroscopy (XPS) analysis confirmed successful cross-linking. The resulting nanofibers exhibited uniform diameters ranging from 100 to 300 nm, with MR cross-linking enhancing their structural stability. Fourier-transform infrared (FTIR) showed that the glycation consumed the –NH2 groups, cleaved sugar units of PUL, and affected the secondary structure of FSG, and thermogravimetric analysis (TGA) demonstrated improved thermal stability, with maximum degradation at 315.5 °C for cross-linked nanofibers (N-MR) compared to 308.2 °C for uncross-linked nanofibers (N). MR significantly improved the mechanical properties, with the tensile strength increasing from 3.01 MPa to 3.59 MPa for the 4:1 blend, and from 1.53 MPa to 3.84 MPa for the 7:3 blend after MR reaction. The water contact angle was maintained below 90°, with values increasing from 46.2° (10:0) to 88.9° (1:1) after MR. The water vapor permeability decreased from 5.35 to 4.71 g mm/m²·h·kPa for the 4:1 blend, while the swelling rates reduced from 774.6 % to 693.9 % for the 1:1 blend after MR, enhancing their barrier properties, and this trend was consistent across all blends. Antioxidant activity was significantly enhanced, with total phenolic content reaching 36.14 mg GAE/100g for the N-MR-1:1 blend, and DPPH and ABTS scavenging activities reached 81.19 % and 75.10 %, respectively. MR cross-linked nanofibers also exhibited antibacterial effects against E. coli and S. aureus, making them promising candidates for sustainable active food packaging.