TG酶调控多糖修饰乳清蛋白成膜性能作用机制研究

Because there are more and more serious "white pollution" and the shortage of oil resources, edible film has become a new trend in the development of food packaging. Due to its good feature, whey protein is the first choice for developing edible film materials.. Although the researches on the protein based edible composite film have been done for many years, the developed protein based edible composite films still have many poorer physical properties than chemical films do. Nowadays, enzymatic cross-linking has showed its potential to catalyze preparation of edible composite film. However, there is few researches on preparation of whey protein based edible composite film using transglutaminase (TGase), and the underlying mechanism is needed for further study that TGase regulates the functional properties of the prepared edible composite film. . Basing on the catalytic characteristic of TGase and excellent film-forming ability of these three typical biological materials such as carboxymethyl chitosan, hydroxypropyl methyl cellulose and calcium carbonate, this project intends to apply TGase to catalyze polysaccharides conjugation of whey protein and modifying the functional properties of whey protein based film, to explore the feasible approach that TGase can catalyze and regulate the preparation of whey protein-polysaccharides edible composite film, and to establish the correlation between regulation function by the TG with microscopic structural characteristics and functional properties of the prepared film, thereby revealing the underlying mechanism that TGase regulating functional properties of whey protein-polysaccharides edible composite film.. This project aims to provide new way to prepare edible films with good performance and lay the scientific basis for effectively regulating and producing the desired edible film with specific functional properties, thereby extend the applications of whey protein.

由于“白色污染”日趋严重以及石油资源的短缺，采用可食膜包装已成为食品包装发展的新趋势,而乳清蛋白由于功能特性显著是开发可食性包装膜的首选材料。然而，尽管蛋白质膜已研究多年，蛋白质膜许多物理性质仍不如化学物合成膜。.本项目基于乳清蛋白、羧甲基壳聚糖、羟丙基甲基纤维素三种典型易得生物材料具有高生物活性和良好成膜特性的突出优势，利用转谷氨酰胺酶的催化特性，探讨应用转谷氨酰胺酶催化多糖-乳清蛋白接枝修饰和影响调控乳清蛋白形成可食复合膜性能的研究；通过系统分析接枝聚合产物的分子结构特征和理化性质，深入探究TG酶催化调控多糖接枝修饰与修饰乳清蛋白制备膜的结构特性和成膜功能性质相关联性研究，揭示TG酶催化调控多糖修饰乳清蛋成膜性能作用机制，旨在为高性能可食膜的制备提供新的思路参考，为实际生产中具有特定需宜功能性质可食膜的有效定制提供科学依据，从而拓展乳清蛋白资源化应用领域。

针对食品塑料包装“白色污染”日趋严重，项目进行可食膜性能修饰及机制研究，以开发可食复合膜的实际应用。项目基于TG 酶的催化特性和羧甲基壳聚糖、羟丙基甲基纤维素多糖的生物反应活性和优良成膜特性，成功制备构建乳清蛋白-羧甲基壳聚糖复合膜和乳清蛋白-羟丙基甲基纤维素复合膜两种膜系。阐明了TG 酶催化多糖修饰乳清蛋白基料膜性能的调控作用，建立了TG 酶催化调控作用与制备膜的微观结构特性以及成膜功能性质的相关性，揭示了TG 酶催化多糖调控乳清蛋白成膜的结构特性和功能特性形成作用机制。以草莓、圣女果、方便面调料、油料为对象进行包装，对构建膜系的实际应用潜能做了研究。研究表明：与单一乳清蛋白膜相比，添加CMC和HPMC均可改善乳清蛋白基膜的抗拉强度、断裂伸长率及水蒸气透过率，添加TGase也可改善同底物比例条件复合膜的抗拉强度、断裂伸长率、透光率、溶解性及水蒸气透过率。确立了乳清蛋白基复合膜可行性成膜途径，在WPC浓度为10%（w/v），甘油添加量与蛋白质量比为1.0:2.2，pH 6.8，TG酶为6 U/g（以蛋白质量计），HPMC添加量为WPC质量的20%时，WPC-HPMC复合膜的性能较好，CMC添加量为WPC质量的20%时，WPC-HPMC-CMC复合膜的性能更优。电泳分析发现经TGase处理乳清蛋白和羧甲基壳聚糖发生交联作用，红外光谱进一步证实TGase可促使羧甲基壳聚糖与乳清蛋白交联。覆盖膜与涂膜包装对圣女果和草莓具有一定的保鲜效果，可有效减缓水分散失和可溶性固形物含量及维生素C含量的下降，复合膜相比乳清蛋白膜保鲜效果更佳，但草莓不适合采用覆盖膜保鲜的方法。构建的WPC-HPMC-CMC复合膜应用于奶茶粉、奶糖以及方便面油料的包装，进行包装应用性能研究，贮藏实验表明复合膜作为奶茶粉包、奶糖、方便面油包包装有较好的可行性，具有应用于部分固体食品内包装的潜能。本课题为乳清蛋白-多糖基复合膜的开发与性能研究奠定了研究基础，为可食性复合膜在食品领域的应用提供重要参考依据。