超声辅助玉米醇溶蛋白基乙烯吸附膜的制备及其香蕉保鲜性能

【目的】乙烯是影响水果品质及货架期的关键植物激素。本研究利用高场强超声波(HIU)对玉米醇溶蛋白(zein)进行物理改性处理，使其蛋白结构舒展，内部活性官能团暴露；利用超声改性zein膜中的活性官能团(如巯基等)与乙烯发生“点击反应”吸附乙烯，从而达到延长水果货架期的目的。【方法】将5 g zein溶于80%醋酸溶液中，选用频率为20 kHz、功率为400 W的超声波经不同时长(0、5、15和30 min)的预处理后，分别取2 mL蛋白溶液移至培养皿(55.0 cm²)中，放置于40℃烘箱干燥24 h，分别得到zein-0膜、zein-5膜、zein-15膜、zein-30膜，通过圆二光谱、内源性荧光、粒径电位仪和扫描电镜分析不同条件超声处理后蛋白结构及形貌的变化；借助物性分析仪和VOC检测仪表征zein膜的力学性能和乙烯吸附性能。以香蕉为研究对象，将超声处理后的zein膜与香蕉放置于同一塑封袋中，室温密闭放置10 d，基于香蕉表皮的褐变程度、香蕉果肉的硬度变化和香蕉失重率分析zein膜延长水果货架期的性能。【结果】高场强超声波处理对蛋白质的高级结构具有修饰作用，...

Preparation of Ultrasound-Assisted Zein Ethylene Scavenger Film and Its Preservation Property of Bananas

【Objective】 Ethylene is an important plant hormone that has a key influence on the quality and shelf life of fruit. In this study, zein was modified to transform into a stretched structure and consequently expose its internal active functional groups by the high-field intensity ultrasound treatment (HIU). Numerous functional groups (-SH) exposed in modified zein film could rapidly react with ethylene via a click reaction, resulting in an extended shelf life of the fruit. 【Method】 The 5 g zein was dissolved in acetic acid-DI water (4:1) solution. The zein solutions were sonicated for 0, 5, 15, and 30 min at an ultrasonic power of 400 W and dried in a drying oven at 40℃ for 24 h to obtain the zein-0 film, zein-5 film, zein-15 film, and zein-30 film. The structures of zein before and after HIU treatment were analyzed by circular dichroism spectroscopy, endogenous fluorescence, particle size potentiometer, and scanning electron microscope. The mechanical and ethylene adsorption properties of zein-based films were characterized by the texture analyzer and the VOC detector. Bananas were used as the climacteric fruit samples to investigate the effectiveness of the zein films as ethylene scavengers. The ultrasonic treated zein film and banana samples were placed in the same plastic sealing bag and then stored at room temperature for 10 d. The performance for extending shelf life was evaluating by browning rate, the flesh hardness, and the weight loss rate of bananas. 【Result】 The HIU treatment (20 kHz, 400 W, 15 min) could effectively stretch the structure of zein. The particle size of the zein and the content of the α-helix were decreased to 1 013.3±6.9 nm, and 45.86%, respectively, and the content of the β-sheet increased to 12.20%. Compared with the zein-0 film, the ethylene adsorption capacity and oxygen resistance of the zein-15 film were increased by 9.486 mg·m^-3·h^-1 and 0.75×10^-16 kg·m·m^-2·s^-1·Pa^-1, respectively. The results including the browning rate, the flesh hardness, and the weight loss rate of bananas indicated that the zein-15 film could effectively extend the shelf-life of bananas. 【Conclusion】 The HIU treatment (20 kHz, 400 W, 15 min) could effectively induce to stretch the zein structure and expose more functional groups, resulting in an improved ethylene adsorption performance of zein. The zein-15 film presented a better ethylene adsorption capacity, oxygen permeability, and mechanical property, leading to an extended shelf life of bananas and its life as the ethylene scavenger.