不同增塑剂对大豆蛋白包装薄膜机械性能稳定性的影响

大豆蛋白膜是以大豆分离蛋白（soybean protein isolate，SPI）为主料，添加适量增塑剂形成具有一定机 械性能的包装薄膜，但其在贮藏过程中机械性能的不稳定是制约其在实际中应用的主要因素。因此本实验选取甘 油、山梨醇、油酸3 种增塑剂制备SPI膜，以贮藏期间抗拉强度、断裂延伸率、水蒸气透过率、水溶失率的变化为 评价指标，探讨添加不同增塑剂的SPI膜在贮藏期间机械性能变化规律。结果表明，以甘油、山梨醇和油酸组合 （2∶1∶1，m/m）作为增塑剂制备SPI膜时，SPI膜机械性能稳定性最佳，与空白组（单独由甘油增塑的SPI膜）相 比，抗拉强度稳定性提高了64%，断裂延伸率稳定性提高了65%，水蒸气透过率稳定性提高了27%，对水的稳定性 提高了20%。本实验可为SPI包装薄膜在实际中更广泛的应用提供一定的理论依据。

Effect of Different Plasticizers on Mechanical Stability of Soybean Protein Packaging Films

Soybean protein packaging film was prepared from soybean protein isolate (SPI) with a proper amount added plasticizer. However, its practical application was limited primarily by its poor mechanical stability. In this experiment, we prepared SPI films with three different plasticizers: glycerin, sorbitol and oleic acid. Changes in the mechanical properties of SPI films during storage were evaluated by measuring tensile strength, elongation at break, water vapor permeability, and water soluble loss rate. Results showed that the combination of glycerol, sorbitol and oleic acid (2:1:1, m/m) could result in the best mechanical stability of SPI film. Compared with the control group (with glycerin alone), the combination of plasticizers increased the stability of tensile strength, breaking elongation, water vapor permeability, and water soluble loss rate by 64%, 65%, 27%, and 20%, respectively. In conclusion, this study will provide a theoretical basis for extensive application of SPI packaging film.