Binary electrospinning of pullulan with different organic acids for enhanced antioxidant and antibacterial properties

Pullulan (PUL), a generally recognized as safe extracellular polysaccharide, can be electrospun into nanofibrous films that serve as promising bio-based food packaging materials. However, their functional properties, such as antioxidant and antibacterial activities, are limited. Therefore, in this study, novel fibrous films were fabricated from PUL and five types of organic acids, namely malic acid, tartaric acid, ascorbic acid, citric acid and tannic acid, through binary electrospinning, and were characterized for their structure and properties. Among the tested formulations, tannic acid loaded-PUL fibrous film exhibited superior macroscopic surface quality and fiber morphology, with an average thickness of 71.61 μm and an average fiber diameter of 200.26 nm. This film also demonstrated the highest acid loading capacity (9.94 mg/g) and loading efficiency (37.67%), along with a relatively high water contact angle (31.61°) and the best mechanical properties, including tensile strength of 5.01 MPa, elongation at break of 38.31%, and Young's modulus of 0.58 MPa, respectively. Furthermore, this nanofibrous film showed the highest relative antioxidant capacity (19.73%/mg) and the strongest relative antibacterial activity against Staphylococcus aureus (6.29 mm/mg inhibition zone). These results provide valuable insights into the development of electrospun PUL-based functional nanofibrous films as sustainable, safe, and active food packaging materials.