以硬脂酸作为增塑剂,胱氨酸作为交联剂制备具有一定力学性能和良好抗湿性能的大豆分离蛋白复合膜.将膜放在25℃,相对湿度为50%的干燥器中平衡两天,用质构仪测定膜的抗拉强度(TS),延伸率(E(%)).在水分活度aw为0.10～0.90的范围内研究了复合膜在25℃的吸湿特性.吸湿速率和吸湿等温线数据分别拟合到Peleg's方程和GAB(Guggenheim-Anderson-de Boer)模型.结果表明:大豆蛋白复合膜的TS、延伸率E(%)以及吸湿速率随着硬脂酸和胱氨酸的添加比率显著地变化.硬脂酸和胱氨酸的最佳添加比率为40:60(w/w)(每升蛋白质溶液中加入10 g混合添加剂),此时,大豆蛋白膜的强度比原来提高2倍,并且有最佳的吸湿速率.吸湿数据和GAB模型有很高的拟合度,拟合系数最高达0.99.%The soy protein isolate(SPI) blend films which have good mechanical properties and better barrier to moisture were prepared by using stearic acid as plasticizers and cysteine as cross-linking reagent. The tensile strength (TS) and percentage elongation (E %) of SPI blend films were determined after conditioning blend film specimens at 25℃ and 50% relative humidity(RH) for 2 days by using Texture Analyzer. Moisture sorption characteristics of the SPI blend films at 25℃ were studied for water activities ranging from 0. 10～0. 90. The moisture sorption rate and sorption isotherm data were mathematically fitted to Peleg's Equation and GAB(Guggenheim-Anderson-de Boer) model, respectively. The results indicated the TS, E % and moisture sorption rate of SPI blend films changed remarkably with the ratio of stearic acid to cysteine in blend films. The optimum ratio of stearic acid to cysteine was 40: 60 (w/w) (10g blend additive /L protein solution) in SPI blend films. The experimental results showed the TS value of the SPI blend films with ratio of 40: 60 was 2 times higher than that of the original SPI films. In addition, the blend films with ratio of 40:60 had the optimum sorption rate. The moisture sorption data of the SPI blend films were well fitted to GAB model. GAB model had the highest R2(0.99).
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