海藻酸钠-明胶-鞣花酸共混膜的制备及特性

以海藻酸钠和明胶为成膜基质，利用溶液共混法荷载鞣花酸，在不同pH值下制备5 种共混膜。采用不透明度、质量损失率、1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl，DPPH）自由基清除率、抑菌圈直径以及傅里叶变换红外光谱（Fourier transform infrared spectroscopy，FTIR）和扫描电子显微镜（scanning electronmicroscope，SEM）表征共混膜的性能和结构。结果表明：添加鞣花酸可以明显改善共混膜的不透明度和DPPH自由基清除率，5 种共混膜体系对大肠杆菌、沙门氏菌、金黄色葡萄球菌均有抑制作用，对革兰氏阴性菌（大肠杆菌、沙门氏菌）的抑制作用较强，改变pH值也会影响共混膜的性能。pH 9.0的海藻酸钠-明胶-鞣花酸共混膜性能最优，其不透明度为15.54，水溶性为0.38%，水蒸气透过系数为0.74×10－10 g/（m·s·Pa），DPPH自由基清除率为57.42%。FTIR谱图和SEM图显示鞣花酸可以与海藻酸钠-明胶共混膜交联，5 种共混膜都有完整的形貌结构和良好的相容性。

Preparation and Characterization of Sodium Alginate-Gelatin-Ellagic Acid Blended Film

Five sodium alginate and gelatin-based films incorporated with ellagic acid were prepared at different pH values by casting method. The properties and structure of the films were characterized by opacity, mass loss percentage, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, the diameter of inhibition zone of bacterial growth, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The results indicate that opacity, DPPH radical scavenging activity of the films was increased significantly by adding ellagic acid, and the film properties were also affected by changing pH. All the blended films exerted antibacterial activity against Escherichia coli, Salmonella and Staphyloccocus aureus especially against Gram-negative bacteria (E. coli and Salmonella). The film prepared at pH 9.0 had the best performance, with opacity of 15.54, water solubility of 0.38%, water vapor transmission coefficient of 0.74 × 10－10 g/(m·s·Pa), and DPPH radical scavenging rate of 57.42%. According to the FTIR spectra and SEM, all films had a complete morphology and structure, and were well cross-linked with good compatibility.