单宁酸对鸢乌贼肌原纤维蛋白膜性能的影响

采用葡聚糖接枝的肌原纤维蛋白，以及酸、碱提取等电点沉淀方法提取的鸢乌贼（Symplectoteuthis oualaniensis）蛋白为原料，分别制得酸提、碱提、糖基化肌原纤维蛋白膜，研究不同浓度的单宁酸对蛋白膜物理性能的影响。结果表明：接枝反应后肌原纤维蛋白中自由氨基含量明显降低。成膜液中的自由氨基和巯基的含量随单宁酸添加量增大而显著降低（P＜0.05）。3 种蛋白膜中，糖基化蛋白膜含水量最低，同时具有较高的水溶性和机械强度。在碱性环境下由于单宁酸氧化交联导致蛋白膜颜色明显变深，表面粗糙度增大。此外，单宁酸的引入使得蛋白膜的拉伸强度增加，而断裂伸长率降低。其中，添加1%的单宁酸的糖基化蛋白具有较高的膜拉伸强度和断裂伸长率，分别为1.26 MPa和118%，同时具有较低的水蒸气透过率。此研究对鸢乌贼蛋白用于可食用包装膜的制备以及延长食品货架期具有重要意义。

Effect of Tannic Acid on the Performance of Squid (Symplectoteuthis oualaniensis) Myofibrillar Protein Films

Glycosylated squid (Symplectoteuthis oualaniensis) myofibrillar protein with dextran and acid- and alkaliextracted squid proteins were applied to prepare biodegradable films. The effect of adding different concentrations of tannic acid (TA) on the physical properties of these films was evaluated. The results showed that glycosylated protein had the lowest free amino group content. TA incorporation significantly reduced the free amino group and --SH content of protein solutions (P < 0.05). Film formed by glycosylated protein had the lowest moisture content, higher water solubility and better mechanical properties. The film exhibited a yellower color and rougher surface due to TA cross-linking under alkaline pH condition. In addition, TA led to higher film tensile strength but lower elongation at break. Among the samples, glycosylated protein-based film with 1% TA had both higher tensile strength and higher elongation at break, which were 1.26 MPa and 118%, respectively. Meanwhile it also had lower water vapor permeability. This study has important implication for exploring squid protein as packaging films to extend the shelf-life of foods.