Combination of Propylene Glycol Alginate and Lauric Acid on Water Retention and Mechanical Properties of Soy Protein Isolate-Based Films

The water sorption, water barrier properties and mechanical behavior of soy protein isolate (SPI) based films combined with propylene glycol alginate (PGA) and lauric acid (La) via a direct- or co-dried blending process were investigated. Higher water retention ability and a single glass transition temperature (Tg) were found when the PGA was added to form different ternary co-dried blending films by a co-drying process, indicating their compatibility. Tg was reduced in the case of higher relative humidity and incorporation of La. The response surface methodology (RSM) indicated that the effect of La content was highly significant (p < 0.05) for the water retention ability and mechanical properties, and the proposed models calculated for the tensile strength and elongation at break showed a good fit. The results revealed the importance of the interactions among lipids, protein and polysaccharide in composite films which also provided evidence for modeling film behavior.

本研究考察了通过直接干燥共混或共干燥共混工艺制备的、添加海藻酸丙二醇酯（propylene glycol alginate，PGA）与月桂酸（lauric acid，La）的大豆分离蛋白（soy protein isolate，SPI）基复合薄膜的吸水性能、阻水性能与力学行为。通过共干燥工艺添加PGA制备不同三元共干燥共混薄膜时，体系保水能力更强，且仅呈现单一玻璃化转变温度（glass transition temperature，Tg），表明各组分间具备良好相容性。当相对湿度升高且引入月桂酸时，体系的玻璃化转变温度会降低。响应面法（response surface methodology，RSM）分析结果显示，月桂酸添加量对保水能力与力学性能存在极显著影响（p < 0.05）；针对抗拉强度与断裂伸长率构建的预测模型拟合效果优异。本研究结果揭示了复合薄膜中脂质、蛋白质与多糖间相互作用的重要性，同时为薄膜性能的建模研究提供了实验依据。