抑菌性桑枝低聚糖微胶囊的制备及结构表征

为了降低桑枝低聚糖的吸湿性，提高稳定性，拓展在产品开发中的应用，本实验以麦芽糊精、乳清蛋白为壁材，桑枝低聚糖为芯材，利用喷雾干燥制备稳定性良好、具有抑制变异链球菌活性的微胶囊。探究壁材种类及与芯材的质量比对微胶囊抑菌率的影响，并对微胶囊的吸湿性、分子结构、微观形态、热稳定性、贮藏稳定性等进行综合评价。结果表明:当复合壁材为麦芽糊精与乳清蛋白且质量比为2:1，壁材与芯材质量比为2:1时，制备的微胶囊具有较高的抑菌率（61.31%±3.34%）与较低的吸湿性（12.31%±1.47%），粒径为6.58±1.76 μm。扫描电镜显示微胶囊颗粒形态完整，表面结构较为光滑；FITR表明微胶囊是麦芽糊精与乳清蛋白通过静电相互作用形成的，桑枝低聚糖较好地被包埋在微胶囊内部；X衍射分析证明桑枝低聚糖在微胶囊中结晶结构发生改变；微胶囊的玻璃化转变温度为96.10 ℃，高于一般贮藏温度。桑枝低聚糖制备成微胶囊后，在温度40.0、60.0 ℃，湿度RH 75.0%、RH 92.5%下稳定性提高。本研究可为桑枝低聚糖作为功能性配料提供一定的理论基础。

Preparation and Structure Characterization of Ramulus mori Oligosaccharides Microcapsules with Antibacterial Activity

In order to reduce the hygroscopicity of Ramulus mori oligosaccharides, improve its stability and broaden the scope of application in product development, microcapsules of Ramulus mori oligosaccharides with good stability and inhibitory against Streptococcus mutans were prepared by spray drying using maltodextrin and whey protein isolate as wall materials. The antibacterial rate, hygroscopicity, molecular structure, microscopic morphology, thermal stability and storage stability of microcapsules were comprehensively evaluated. The results showed that the microcapsules had high antibacterial rate (61.31%±3.34%), low hygroscopicity (12.31%±1.47%) and small particle size (6.58±1.76 μm) when prepared by maltodextrin/whey protein isolate ratio 2:1 and the core/wall ratio 1:2. Scanning electron microscopy showed that the microcapsules had complete particle morphology and smooth surface structure. FITR showed that the microcapsules were formed by the electrostatic interaction between maltodextrin and whey protein, and the oligosaccharides were embedded into the microcapsules. X-ray diffraction analysis proved that the crystalline structure of Ramulus mori oligosaccharides microcapsules had been changed. The glass transition temperature of the microcapsules was 96.10 ℃, which was higher than the general storage temperature. What's more, the stability of Ramulus mori oligosaccharides was significantly improved at the temperature of 40.0, 60.0 ℃, and the humidity of RH 75.0%, RH 92.5% when embedded into the microcapsules. This research was expected to provide a theoretical basis for Ramulus mori oligosaccharides as functional ingredients.