Abstract:Methods to improve the mechanical and barrier properties of gelatin film have attracted considerable attention in the field of edible film manufacture. Here, different concentrations of tannins (0, 10, 20, 30, and 40 mg/g) were added to the gelatin solution and edible film was prepared by the casting method. The physicochemical properties of the film were investigated. The results suggested that incorporation of tannin effectively increased the tensile strength (TS), but reduced the elongation at break (EAB) of the film. The highest TS (22.10 MPa) and the lowest EAB (40.12%) were achieved with 30 mg/g tannin (dry weight). Compared with control, the film containing tannin showed decreased water solubility, water vapor permeability, and oxygen permeability. At the concentrations of tannin studied, the minimum values for water vapor permeability, water solubility, and oxygen permeability were 1.49×10-11 g/(Pa?s?m), 27.76%, and 21.63 Meg/kg, respectively. In addition, differential scanning calorimetry (DSC) analysis indicated that the thermal stability of tannin-gelatin films was also enhanced. Moreover, Fourier transform infrared spectroscopy (FT-IR) analysis showed physical crosslinking effect between tannin and gelatin, dominated by hydrogen bonding and hydrophobic bonding. Thus, the tannin-gelatin film shows potential development value in the field of food packaging.
