Abstract In this study, tri-functional trimethylolpropane-tris-(2-methyl-1-aziridine) propionate (TMPTAP) and plant-derived caffeic acid (CA) were used as a cross-linking system to simultaneously enhance the strength and retain elongation at break (EB) of soy protein isolate (SPI) films. The cross-linking reactions in the film by CA/TMPTAP system were examined with attenuated total reflectance-Fourier transform infrared spectroscopy, 13 C Nuclear Magnetic Resonance, UV– vis spectroscopy, X-ray diffraction, and thermogravimetric analysis. The film morphologies were observed with the scanning electron microscopy and atomic force microscopy. The results indicated that the catechol groups and oxidized quinone in CA readily reacted with the amine/sulfhydryl groups on SPI, while the tri-functional TMPTAP might react with carboxyl groups through aziridine ring-opening reactions. As expected, the modified SPI films by cross-linking with the CA/TMPTAP system simultaneously enhanced the strength and EB of SPI films. The tensile strength and EB of SPI/TMPTAP/CA film, in comparison to untreated SPI film, were improved by 103.0% and 17.1%, respectively, as a result of the relatively ordered three-dimensional cross-linked network among TMPTAP, CA, and SPI. The water absorption of SPI/TMPTAP/CA film also showed a 49.2% reduction compared to that of the unmodified SPI film.

中文翻译：

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通过咖啡酸掺入和三功能氮丙啶杂交改善大豆分离蛋白薄膜的理化性质

摘要 本研究以三功能三羟甲基丙烷-三-(2-甲基-1-氮丙啶)丙酸酯 (TMPTAP) 和植物来源的咖啡酸 (CA) 作为交联体系，同时提高强度和保持伸长率。大豆分离蛋白 (SPI) 薄膜的断裂 (EB)。用衰减全反射-傅立叶变换红外光谱、 13 C 核磁共振、紫外-可见光谱、X 射线衍射和热重分析检查 CA/TMPTAP 系统在薄膜中的交联反应。用扫描电子显微镜和原子力显微镜观察薄膜形貌。结果表明，CA中的儿茶酚基团和氧化醌很容易与SPI上的胺/巯基反应，而三官能 TMPTAP 可能通过氮丙啶开环反应与羧基反应。正如预期的那样，通过与 CA/TMPTAP 系统交联的改性 SPI 薄膜同时增强了 SPI 薄膜的强度和 EB。与未经处理的 SPI 薄膜相比，SPI/TMPTAP/CA 薄膜的拉伸强度和 EB 分别提高了 103.0% 和 17.1%，这是由于 TMPTAP、CA、和SPI。与未改性的 SPI 薄膜相比，SPI/TMPTAP/CA 薄膜的吸水率也降低了 49.2%。由于 TMPTAP、CA 和 SPI 之间相对有序的三维交联网络，分别提高了 103.0% 和 17.1%。与未改性的 SPI 薄膜相比，SPI/TMPTAP/CA 薄膜的吸水率也降低了 49.2%。由于 TMPTAP、CA 和 SPI 之间相对有序的三维交联网络，分别提高了 103.0% 和 17.1%。与未改性的 SPI 薄膜相比，SPI/TMPTAP/CA 薄膜的吸水率也降低了 49.2%。