蓝圆鲹鱼油微胶囊的结构表征与体外消化特性

蓝圆鲹鱼油不饱和脂肪酸含量丰富，但极易被氧化而失去营养价值，目前微胶囊化包埋已成为防止鱼油氧化的稳态化技术之一。本研究采用扫描电子显微镜、激光扫描共聚焦显微镜（laser scanning confocal microscope，LSCM）、傅里叶变换红外光谱（Fourier transform infrared spectroscopy，FTIR）及其二阶导数拟合和pH-stat法对喷雾干燥法制备的以阿拉伯树胶、明胶和海藻糖为壁材的蓝圆鲹鱼油微胶囊的形态结构、结构形成过程中的相互作用与体外模拟消化特性进行评价。结果表明：蓝圆鲹鱼油微胶囊颗粒圆整，表面光滑、致密；LSCM观察发现蓝圆鲹鱼油微胶囊呈现单核的腔体结构，壁材中明胶蛋白均匀分布在微胶囊的囊壁上，而鱼油被包裹在囊壁中。FTIR分析显示，壁材及芯材的特征吸收峰均出现在蓝圆鲹鱼油微胶囊的FTIR图谱中，证实了包埋结构的形成。经喷雾干燥后，蓝圆鲹鱼油微胶囊壁材中明胶蛋白质的二级结构中α-螺旋含量减少，说明蛋白分子间发生氢键缔合反应，增强了微胶囊结构的稳定性。体外模拟消化实验表明，鱼油微胶囊在消化过程中其游离脂肪酸释放率由快变慢，120 min时累积释放量为72.62%；LSCM观察发现，在消化过程中，鱼油微胶囊的芯材呈现出由中心向壁材表面迁移扩散并逐步释放的特征。本研究为微胶囊产品开发、应用评价体系的构建及其应用提供理论参考。

Structure Characterization and in Vitro Digestibility of Microencapsulated Decapterus maruadsi Fish Oil

Decapterus maruadsi fish oil is rich in unsaturated fatty acids, but it is easily oxidized, causing loss of nutritional value. Microcapsulation has emerged as one of the best strategies to prevent fish oil oxidation. In the present study, scanning electron microscopy, laser scanning confocal microscopy (LSCM), Fourier transform infrared spectroscopy (FTIR) with second derivative fitting, and pH-stat method were used to investigate the morphological structure, the interaction during the formation process and the simulated digestion characteristics in vitro of microencapsulated Decapterus maruadsi fish oil prepared by spray drying using gum arabic, gelatin and trehalose as wall materials. The results showed that the fish oil microcapsules were spherical granules with smooth and compact surfaces. Under LSCM, the fish oil microcapsules presented a mononuclear cavity structure with gelatin evenly distributed on the wall and the fish oil wrapped inside the wall. The FTIR of microcapsules revealed the characteristic absorption peaks of the wall and core materials, which confirmed the formation of an embedded structure. The α-helix content of the secondary structure of gelatin decreased after spray drying, demonstrating the occurrence of protein-protein hydrogen bonding, which enhanced the structure stability of the microcapsule structure. In vitro simulated digestion experiments showed that during the digestive process free fatty acids were released fast initially and then slowly; the accumulative release amount was 72.62% at 120 min. LSCM revealed that during digestion, the core material was migrated to the wall surface and released gradually. The above results provide theoretical data for the development, application and evaluation of microcapsule products.