静电喷涂过程中成膜组分对壳聚糖膜结构和性能的影响及其机制研究

The electrostatic spraying (ES) technology using water soluble material has been rapidly developed in recent years since its advantage of saving raw material, increasing coating efficiency, improving film quality and achieving industrial continuous operation. However, few reports of its application on the coating preservation of food materials are available. In present project ES technology will be applied to prepare chitosan film; the influence of molecular weight, deacetylation and concentration of chitosan, and the type and content of plasticizer/surfactant on fluidity, wetting ability, and electrical properties of film-forming solution will be investigated; the ES atomization effect will be determined by using image method combined with Faraday cup observation; the molecular interaction and micro-structure of film will be analyzed by using infrared spectroscopy, C nuclear magnetic resonance spectra, atomic force microscopy and etc.; and then the antibacterial activity, thermal stability and other macro characteristics will be analyzed. Overall, the effects of film-forming solution on ES performance and film property will be systematically studied, and the mechanism of its influence on structure-activity relationship of ES chitosan film will be further elucidated. Meanwhile, the high quality of ES chitosan film will be obtained by the optimization of film forming conditions, and the food perseveration application of this ES chitosan film on putrefactive strawberry, salmon fillets, and cheese, with different property of surface and shape, will be also investigated. All those results will provide the scientific evidence of ES chitosan film on food perseveration for the theoretical research and practical application in industry.

静电喷涂水溶性物料是近年来快速发展的新型技术，能够节省原料、提高涂覆效率、改善涂层性能，利于实现工业化连续操作。然而将其应用于食品涂膜保鲜的研究还鲜见报道。本项目采用新型静电喷涂设备制备壳聚糖膜，分析壳聚糖分子量、脱乙酰度及浓度，增塑剂及表面活性剂种类与含量等对膜液流动、润湿及电学性能的影响，利用图像学手段结合法拉第杯观测膜液静电喷涂雾化效果，采用红外光谱、核磁共振碳谱、原子力显微镜等手段研究膜的分子作用及微观结构，结合膜抗菌活性、热稳定性等宏观特性分析，综合考察成膜组分对膜液静电喷雾及成膜效果的影响，进一步探讨其影响静电喷涂壳聚糖膜构效关系的机理。同时优化成膜配方获得性能良好的壳聚糖膜，以具有不同表面组成、形貌的易腐败食品（草莓、三文鱼片、奶酪）为研究对象，考察静电喷涂壳聚糖膜对不同食材的涂覆保鲜效果。研究成果将为深化静电涂膜在食品保鲜方面的理论研究及工业化应用提供科学依据。

静电喷涂应用于食品涂膜保鲜是近年发展起来的研究热点，该技术可节省原料、提高涂覆效率、改善涂层性能，且利于工业化连续操作。物料组成及固有特性会对静电喷涂效果产生显著影响，但其程度及机理鲜有研究。本项目围绕这一科学问题，采用新型静电喷涂系统制备壳聚糖膜，研究成膜组分及分子特性（分子量、脱乙酰度）对静电喷雾及成膜效果的影响，分析成膜微观结构与宏观性能的关系。此外，考察静电喷涂壳聚糖膜对不同易腐食品的涂覆保鲜效果。研究结果表明，随着壳聚糖分子量与浓度的增加，分子中的胺基比例逐渐增高，促进了分子间的相互作用及分子链间的缠绕作用，使得膜液具有更高的粘度、电导率和表面张力。膜液性质影响了壳聚糖液滴在电场中的运动，分子量为14.67 kDa的膜液具有最大的雾化角度。受电荷转移和分子链缠绕的影响，大分子量壳聚糖在成膜过程中形成了更加完整的结构，团聚现象更为明显，结晶程度也逐渐加剧，成膜后水蒸气阻隔能力及机械强度显著增加，分子量为49.01 kDa的壳聚糖在 0.5％浓度下具有最佳表现。壳聚糖膜液的表面张力和粘度随脱乙酰度的增加而下降，电导率则呈相反趋势。不同脱乙酰度壳聚糖膜液在静电喷涂过程中液滴平均中值直径为6.4至13.9μm，相较常规喷涂技术展现出更为优良的雾化效果。膜液雾化角和液滴尺寸随脱乙酰度增加而减小，有助于在成膜过程中形成更完整、结晶度更大、表面更粗糙的结构，从而在宏观上表现出更佳的防水性和抗拉强度，浓度为1.2%、脱乙酰度为88.1%的壳聚糖性能最优。此外，静电喷涂壳聚糖膜对表面性质均一的马苏里拉奶酪涂覆更为完全，而对形状不规则的草莓涂覆效果较差，但该方法对不同食材（草莓、奶酪与三文鱼）均具防腐保鲜作用，且壳聚糖分子特性对保鲜效果的影响与其对成膜性能的影响规律一致。通过本项目研究，阐明了壳聚糖分子特性对静电喷涂成膜效果的影响机理，为静电涂膜在食品保鲜方面的工业化应用提供科学依据及技术支撑。