Characterization\nof Biodegradable Films Based on Tomato\nSeed Protein Isolate

Tomato seed protein isolate (TSPI) (3, 4, and 5 g) was\nused to\nform protein-based edible films. The incorporation effect of glycerol\n(GLY) (35, 42.5, and 50% w/w based on the dry weight of TSPI) and\ntragacanth gum (20% w/w based on the dry weight of TSPI) on the characteristics\nof TSPI films was investigated. Response surface methodology (RSM)\nusing a central composite rotatable design was used to predict the\neffects of the TSPI and GLY concentrations on responses. The experimental\ndata were adequately fitted into a linear model for all of the variables\nexamined. The optimum concentrations of TSPI and GLY were 3.925 g\nand 35% w/w based on the dry weight of TSPI, respectively. Under this\ncondition, the characteristics of TSPI films resulted in the optimum\nopacity (14.17), water solubility (48.07%), water vapor permeability\n(1.355 g mm/kPa h m<sup>2</sup>), total color differences (52.33),\ntensile strength (3.5 MPa), elongation at break (6.582%), and L* (63.60).\nTSPI films exhibited a semicrystalline nature, which was proved by\nthe results of SEM and XRD analysis. Fourier transform infrared spectroscopy\n(FTIR) showed the presence of strong hydrogen bonding between the\nprotein chains and glycerol. The results showed that TSPI had a good\nfilm-forming capacity, creating a homogeneous film with good physiochemical\nproperties. However, this study presented some of the characteristics\nof TSPI films, aiming to provide new research ideas for the wide application\nand further study of TSPI edible films.