壳聚糖基食品保鲜涂膜中纳米SiOx的原位合成机理及构效关系

Adding inorganic nanoparticles is beneficial to improve the properties of chitosan based food preservation coating. However, the nanoparticles are still agglomerative and scattered unevenly, and the food preservation properties of the coatings are affected seriously. The distribution of nanoparticles in high molecular materials can be improved by in-situ synthesis and in-situ modification. In this project, SiOx nanoparticles will be synthetized in the food preservation coating by in-situ synthesis method and the CaCO3 nanoparticles will be synthetized in the food preservation coating by in-situ modification method. Besides, the in-situ synthesis mechanism of nano SiOx in the chitosan based food preservation coating and the structure-activity relationship of the food preservation composite coating will be also discussed. Meanwhile, the in-situ synthesis mechanism of nano SiOx will be clarified by analysing the influence of coating synthetic factors on its microstructure. The mathematical model about the microstructure and properties index of in-situ synthesis SiOx chitosan based coating will be also established by mathematical statistics method, and the structure-activity relationship of the food preservation coating will be clarified. The enhancing mechanism of nano CaCO3 in the food preservation coating will be ascertained by the establishment and verification of structure-activity relationship. And then, the way of antibacterial action and the antibacterial mechanism of the modified chitosan based food preservation composite coating on seafood dominant spoilage bacteria can be illustrated by the effect of the food preservation composite coating on the structure and permeability of cell membrane, metabolic activity and protein expression of the target bacteria. Afterwards, the modified chitosan based food preservation composite coatings are applied on Sciaenops Ocellatus preservation, and the preservation effect is verified. This project is a new exploration on in-situ synthesis and modification. It can provide theory basis and method instruction for the improvment of food preservation coating performance.

添加无机纳米粒子有助于改善壳聚糖食品保鲜涂膜性能，但目前仍存在颗粒团聚、分散不均等现象，严重影响食品保鲜效果。原位合成和原位改性技术可改善纳米粒子在高分子材料中的分布，本课题拟采用原位合成法引入纳米SiOx，采用原位改性法引入纳米CaCO3，并探讨涂膜中纳米SiOx原位合成机理及涂膜构效关系。通过分析涂膜合成因素对其微结构的影响，阐明纳米SiOx原位合成机理；采用数理统计方法建立原位合成纳米SiOx壳聚糖涂膜微结构与性能指标间的数学模型，阐明涂膜构效关系；通过构效关系建立和验证，探明纳米CaCO3对涂膜的增强机理。通过研究其对目标菌细胞膜结构、膜通透性、代谢活力、蛋白质表达等的影响，阐明改性壳聚糖基涂膜对水产品优势腐败菌的抗菌作用途径及机理；将改性的壳聚糖涂膜应用于美国红鱼保鲜，验证其对贮藏品质的影响。本项目是原位合成和改性技术的一种新探索，可为改善食品保鲜涂膜性能提供理论依据和方法指导。

无机纳米粒子可显著提高壳聚糖食品保鲜涂膜性能。为改善颗粒团聚、分散不均等现象，深层次揭示复合涂膜的构效关系，本项目采用原位合成法在多糖复合涂膜中引入纳米SiOx，采用原位改性法引入纳米CaCO3，并在此基础上引入改性后的抗菌纳米粒子。借助XRD、FT-IR、SEM、TEM等表征分析阐明了涂膜的微结构状态，测定了涂膜的理化性能，分别以美国红鱼、淡水鱼丸和生姜为保鲜对象，测定了涂膜的保鲜性能。在综合分析的基础上揭示了涂膜的构效关系。以水产品优势腐败菌铜绿假单胞菌和腐败希瓦氏菌为作用对象，测定了复合涂膜的抗菌性能，及复合涂膜作用前后菌体细胞膜的完整性、膜通透性、ATP酶和AKP酶的活性、蛋白质表达等，分析并阐明了复合涂膜的抗菌机理，为更深层次地揭示保鲜涂膜的构效关系提供了重要证据。.原位合成SiOx可显著改善壳聚糖复合涂膜的理化性能，纳米SiOx与壳聚糖分子间形成了氢键，且有化学键方式结合。制备工艺条件对涂膜的性能均有影响，当SiOx添加量为0.03%、壳聚糖浓度为1.5%、甘油添加为0.1%时，原位合成SiOx壳聚糖复合涂膜的理化性能及保鲜性能更优。以ZnCl2为原料，采用溶剂热法制备的Ti掺杂ZnO纳米球较其他粉体的抗菌性能更优，Ti/ZnO粉体破坏细菌的细胞壁，使其内容物泄漏，进而杀菌。改性后纳米颗粒表面存在大量羟基及亲油性基团，易与壳聚糖发生氢键作用，添加Ti掺杂ZnO粉体及纳米ZnO/TiO2复合粉体显著改善了原位合成纳米SiOx的壳聚糖涂膜的理化性能，进一步提高了保鲜性能。原位改性CaCO3的引入可显著改善壳聚糖复合涂膜的理化性能，纳米CaCO3与壳聚糖分子间的相容性好，理化性能和保鲜性能更优。引入改性后的抗菌微纳米颗粒使涂膜对水产品优势腐败菌的作用更加强烈，抗菌性能及保鲜性能更优。.综上，原位合成和原位改性使微纳米颗粒表面的羟基及亲油基团与壳聚糖等多糖分子之间形成了氢键或化学键方式结合，颗粒与壳聚糖分子间的相容性好，使涂膜的理化性能和保鲜性能更优。