Abstract: 【Objective】 This study was aimed to investigated the protective effect of potato starch and corn starch on the activity of microcapsulated Pediococcus acidilactici in the process of freeze-drying,as well as the effect on the acid and bile salts resistance of Pediococcus acidilactici and the storage stability of Pediococcus acidilactici,so as to explore ideas and provide theoretical basis for the development and utilization of resistant starch and probiotic protection technology. 【Method】 Three groups of microcapsules were prepared with 3.0% sodium alginate and 0.8%chitosan concentration:Control group,test group 1 (T1) and test group 2 (T2).In control group, 2% glycerol was used as lyophilizing agent,in group T1, 2% glycerol and 10% potato starch was used as lyophilizing agent,and in T2 group, 2% glycerol and 10% corn starch was used as lyophilizing agent.The morphology,mechanical strength,embedding rate,bacterial load,tolerance of artificial gastrointestinal tract in vitro and storage performance of the microcapsules were evaluated.【Result】 ①The embedding rate of microcapsule in groups T1 and T2 was significantly higher than that in control group (P＜0.05).②The lyophilization protection rate of groups T1 and T2 reached more than 70%,which were both significantly higher than that of control group (P＜0.05),and with a higher lyophilization protection rate of 77.66% in group T2.③The particle size,mechanical strength,bacterial load of microcapsules in groups T1 and T2 were significantly higher than those in control group (P＜0.05).④The in vitro tolerance test of artificial gastrointestinal fluids revealed that the survival rate of groups T1 and T2 in simulated gastric fluid containing pepsin was higher than that of control group,and the difference was significant after 2 h (P＜0.05).The Pediococcus acidilactici microcapsules in three groups started to release rapidly in simulated intestinal fluid after 10 min,and at 1 h,they were basically completely disintegrated.Pediococcus acidilactici microcapsules in groups T1 and T2 were stable in bile salt environment.The survival rate of Pediococcus acidilactici in groups T1 and T2 in bile salt environment was significantly higher than that of control group (P＜0.05) after 4 h.⑤Three groups of microcapsules were stored at 25 ℃ for 8 weeks,the survival rate of Pediococcus acidilactici in groups T1 and T2 was significantly higher than that in control group (P＜0.05),and the survival rate of Pediococcus acidilactici in group T2 was higher (52.29%).After 8 weeks of storage at －20 ℃,the survival rate of Pediococcus acidilactici in groups T1 and T2 was higher than that in control group,but the difference was not significant (P＞0.05).【Conclusion】 In summary,through the measures of microencapsulation technology and the addition of plant starch as a protective agent,the freeze-drying protection rate and storage performance of Pediococcus acidilactici microcapsules could be improved,among which corn starch had higher freeze-drying protection and storage performance of Pediococcus acidilactici microcapsules.The results could provide reference for the development of Pediococcus acidilactici microcapsules with sodium alginate and chitosan as wall materials.

Key words: Pediococcus acidilactici; potato starch; corn starch; microcapsules