Effect of soybean peptides on structure and functional properties of soluble soybean polysaccharide edible films

Edible films developed from food biopolymers have made significant progress in recent years. In this work, water-soluble edible packaging films formed by soluble soybean polysaccharide (SSPS) and soybean peptides (SPEs) with different molecular weights (500, 1000, and 3000 Da) were developed and characterized. The results demonstrated that the incorporation of SPEs markedly enhanced the performance of the SSPS film , improving its optical properties, mechanical strength, and thermal stability. As the molecular weight increased, both the tensile strength and the elongation at break of the composite film improved, reaching 7.9 ± 0.3 MPa and 41.4 ± 2.7 %, respectively. The FTIR results indicated that SPEs primarily interacted with SSPS through intermolecular hydrogen bonding. The incorporation of 3000 Da SPEs enhanced the internal orderliness, constructing a more compact network structure, which significantly improved the heat resistance of film networks. Additionally, the incorporation of SPEs enhanced the disintegration property and contact angle value of composite films. The composite film carrying clove essential oil had obvious inhibition activity to S. aureus and E. coli . The study could contribute to developing the novel type of instant edible films and provide a basis for the load of active substances.