水杨酸/季鏻盐双改性壳聚糖抗菌保鲜剂的制备及表征

该研究以天然高分子壳聚糖（CS）为基体，首先分别用水杨酸（SA）和季鏻盐（TPPB）接枝改性壳聚糖，通过单因素实验确定壳聚糖和水杨酸、季鏻盐的最佳摩尔比，得到SA-CS和TPPB-CS聚合物，再以水杨酸壳聚糖衍生物为底物，加入不同摩尔比的季鏻盐，通过水溶性分析选出最佳摩尔比，得到SA-CS-TPPB聚合物；并通过红外光谱、核磁共振、X射线衍射和热重分析等对所得到的三个聚合物进行结构性能表征，最后通过抑菌圈实验分析SA-CS、TPPB-SA和SA-CS-TPPB聚合物的抗菌性能。结果表明，最优反应摩尔比CS:TPPB:SA为1:1:0.75；所得壳聚糖衍生物有很好的溶解性和抗菌性，溶解性可达100.00%，对金黄色葡萄球菌和大肠杆菌有很好的抑制效果，且对金黄色葡萄球菌的抑制效果优于大肠杆菌。SA对提高CS抗菌性要比TPPB效果好，季鏻盐对提高壳聚糖水溶性比水杨酸好，采用水杨酸和季鏻盐共同改性壳聚糖对提高其水溶性和抗菌性有协同增效作用，所得壳聚糖衍生物比壳聚糖有更好的成膜性能，为壳聚糖改性在果蔬涂膜保鲜中的应用提供理论依据。

Preparation and Characterization of Salicylic Acid/Quaternary Phosphonium Salt-modified Chitosan as an Antibacterial Preservative

Natural polymer chitosan (CS) was modified using salicylic acid (SA), then quaternary phosphonium salt (TPPB). Single-factor experiments were then carried out to determine the optimal molar ratios of CS to SA and TPPB and to acquire SA-CS and TPPB-CS polymers. Following this, SA-CS derivatives were adopted as substrates and mixed with TPPB at different molar ratios to obtain the optimal molar ratio based on the water solubility results. Eventually, SA-CS-TPPB polymers were obtained. The three different polymers were subjected to infrared spectroscopy, nuclear magnetic resonance, X-ray diffraction, and thermogravimetric analysis to analyze their structures and properties. Finally, according to the zone of inhibition results, the antibacterial performances of SA-CS, TPPB-CS, and SA-CS-TPPB were examined. The results demonstrate that the optimal molar ratio (CS:TPPB:SA) is 1:1:0.75 and all the CS derivatives exhibit excellent solubility and antibacterial performances. Their solubility can reach up to 100.00%, and they show satisfactory inhibitory effects against Escherichia coli but even more so against Staphylococcus aureus. SA can better enhance the antibacterial performance of CS compared to TPPB, whereas TPPB is more effective at increasing CS solubility than SA. By modifying CS using both SA and TPPB, the solubility and antibacterial activity of CS can be improved synergistically. The CS derivatives acquired also have better film forming characteristics than CS alone. These findings are of theoretical importance for future CS modification and its application as a coating for fruit and vegetable preservation.