基于壁材阻湿性的微囊构建及其对益生菌常温储藏的保护机制

Microcapsules suitable for probiotics storage at ambient temperature will extend their shelf life and application in food industry. Thus the study of microcapsule fabrication and its protection mechanism of probiotics at ambient temperature has practical significance. Using food-grade amphiphilic polyelectrolytes (protein and modified starch) as encapsulating materials, probiotics microcapsules with different hygroscopicity will be fabricated by adjusting their electrostatic and hydrophobic forces. And the mechanism of microcapsule hygroscopicity affecting probiotics survival during ambient storage will be clarified. Research contents are as follows. 1) The electrostatic and hydrophobic interactions of whey protein isolate (WPI) and octenyl succinate starch (OSA-starch) will be adjusted by experiment parameters and quantified, and the corelation between WPI/OSA-starch interaction and moisture-barrier property of WPI/OSA-starch complex will be investigated. 2) WPI/OSA-starch complex with different moisture-barrier properties will be used as encapsulating material. Dry probiotics microcapsules will be prepared using the method of complex coacervation and spray drying, combined with the adhesion mechanism of probiotics to protein. The corelation between preparation parameters and hygroscopicity of microcapsules will be studied. 3) Probiotics microcapsules with different hygroscopicity will be prepared. The inactivation kinetics of encapsulated probiotics, moisture absorption kinetics and glass transition of microcapsules and changes of cell components during ambient storage will be investigated. Finally, mechanism for how microcapsule hygroscopicity affects probiotics survival during storage will be clarified from physical and physiological levels. The knowledge gained in the project is expected to provide an important theoretical basis for designing probiotics microcapsules and improving the ambient storage of probiotics.

利于益生菌常温储藏的微囊可拓展益生菌货架期和应用范围，因此，益生菌微囊构建及其对益生菌常温储藏保护机制研究具有重要的现实意义。本项目以食品级两亲性聚电解质（蛋白/变性淀粉）为壁材，调控壁材间静电作用力和疏水作用力，构建不同吸湿性益生菌微囊，解析常温储藏下微囊吸湿性对益生菌存活的影响机制。研究内容：1）以乳清分离蛋白和辛烯基琥珀酸淀粉为研究对象，调控并定量表征两者静电作用和疏水作用，解析相互作用与蛋白/淀粉复合物阻湿性的关联；2）以不同阻湿性复合物为壁材，结合益生菌/蛋白粘附规律，复合凝聚-喷雾干燥法制备干态益生菌微囊，探索制备参数与微囊吸湿性的相关规律；3）制备不同吸湿性益生菌微囊，考察其常温储藏下的益生菌失活动力学、微囊吸湿动力学、微囊玻璃化转变等特性，解析细胞组分变化，从物理、生理生化角度阐明微囊吸湿性对益生菌储藏存活的影响机制。研究成果将为益生菌微囊设计和常温储藏提供理论支撑。

利于益生菌常温储藏的微囊可拓展益生菌货架期和应用范围，因此，益生菌微囊构建及其对益生菌常温储藏保护机制研究具有重要的现实意义。本项目系统考察了三种复合凝聚体系（乳清分离蛋白/阿拉伯胶、明胶A/阿拉伯胶、明胶A/酪蛋白酸钠）荷载益生菌的研究，特别是基于疏水性不同的蛋白/多糖复合凝聚体系（明胶A/阿拉伯胶）和异蛋白复合凝聚体系（明胶A/酪蛋白酸钠），构建了不同吸湿性益生菌微囊，阐明了微囊吸湿特性对益生菌常温储藏存活的调控机制。研究结果表明：复合凝聚pH是影响益生菌微囊保护的重要因素，基于明胶A的碱性等电点，可构建中性pH的复合凝聚体系：明胶A/阿拉伯胶、明胶A/酪蛋白酸钠；与阿拉伯胶、明胶A、酪蛋白酸钠相比，明胶A/阿拉伯胶、明胶A/酪蛋白酸钠复合凝聚体系显著提高了各胁迫条件下的益生菌存活率；对比明胶A/阿拉伯胶、明胶A/酪蛋白酸钠复合凝聚体系，GE/Cas的异蛋白复合凝聚体系对益生菌的保护效果显著优于GE/GA的蛋白/多糖复合凝聚体系，这是由于异蛋白复合凝聚体系的壁材疏水性较高，降低了微囊的吸湿性和润湿性，减缓微囊在模拟胃肠液过程中的崩解速率。本项目探索了复合凝聚法制备益生菌微囊的关键参数，阐明了微囊吸湿性对益生菌常温储藏存活的影响机制，对解决益生菌常温储藏失活瓶颈具有重要的应用指导意义。