Fabrication and characterization of crosslinked pea protein isolated/pullulan/allicin electrospun nanofiber films as potential active packaging material

In this study, pea protein isolated/pullulan electrospun nanofiber films (PPI/PUL NFs) were successfully cross-linked by heating through Maillard reaction. PPI/PUL NFs were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and water contact angles (WCAs). The morphological analysis illustrated that the cross-linking degree of these NFs varied with the glucose content, and the maximum glucose content was 3.0% (w/v). The fiber structure was broken down when the glucose content exceeded 3.0% (w/v), which was attributed to partial swelling and fusion of nanofibers after cross-linked by glucose. FTIR results indicated that the Maillard reaction occurred between the PPI and glucose during the thermal crosslinking process. Cross-linking dramatically improved the thermal stability, WCAs, insolubility and barrier properties of PPI/PUL NFs, which were needed to be solved urgently in biobased food packaging material. The cross-linked PPI/PUL NFs with a 2.0% glucose showed the most hydrophobic surface (WCAs of 104.5° and water vapor transmission rate of 29.3%). The antimicrobial activity of allicin-loaded PPI/PUL NFs (PPI/PUL-AC NFs) was evaluated, and the maximum size of the inhibition zone of cross-linked PPI/PUL-AC NFs against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was 16.5 mm and 12.8 mm, respectively. This study not only offered an effective pathway to protect the biological activity of allicin under heating conditions by electrospinning but also provided a reference on novel crosslinking approach of PPI/PUL NFs, which allowed PPI/PUL-AC NFs to be a highly promising platform for antimicrobial food packaging.