Abstract: In this study, sodium alginate and chitosan were used together to embed Streptococcus thermophilus in the presence of galactooligosaccharide (GOS) for the preparation of alginate/chitosan bilayer synbiotic microcapsules. The preparation process and the storage stability and controlled release of the resulting microcapsules were investigated. The bilayer synbiotic microcapsules prepared at a sodium alginate concentration of 2 g/100 mL had desired appearance, particle size and embedding rate and were found to be stable when exposed to simulated gastric fluid; however, complete disintegration of these microcapsules and consequent complete release of Streptococcus thermophilus were observed when the exposure time was up to 150 min. The survival rate of free Streptococcus thermophilus in suspensions with or without added GOS declined greatly after refrigerated storage, only 0.32% on the 13th day for Streptococcus thermophilus suspension in the absence of GOS compared to 14.64% for the presence of GOS. For bilayer synbiotic microcapsules, the bacterial survival rate descended only slightly during the entire storage period regardless of the presence or absence of GOS and remained as high as 93.64% and 87.98%, respectively.

Key words: bilayer microcapsules；controlled release；storage；stability；bacterial survival rate

摘要： 以海藻酸钠和壳聚糖为包埋剂,在其中加入低聚半乳糖(galacto-oligosaccharides,GOS),对嗜热链球菌(Streptococcus thermophilus)进行包埋,制备海藻酸钠/壳聚糖双层合生元微胶囊,并对其制备工艺、控制性释放和储藏稳定性进行研究.结果表明:当海藻酸钠的质量浓度为2g/100mL时,微胶囊的外观、粒径和包埋率均较好；在对得到的双层微胶囊进行人工胃肠道抗逆实验,发现双层包埋的微胶囊在人工胃液中比较稳定,S.thermophilus 基本不被释放,而当双层微胶囊在人工肠液液中到150min后微胶囊已经完全崩解,乳酸菌释放完毕.通过对游离状态和双层包埋微胶囊菌体存活率进行计算,游离状态的S.thermophilus菌悬液经过冷藏,菌体存活率下降十分明显,未添加GOS的菌悬液在第13天菌体存活率仅有0.32％,而添加GOS的菌悬液活菌存活率相对较高,可以达到14.64％;但双层微胶囊在添加和未添加GOS时,菌体存活率在整个储藏期内下降幅度均较小,在第17天时,菌体存活率依然能够达到93.64％和87.98％.

关键词: 双层微胶囊；控制性释放；储藏；稳定性；菌体存活率