Optimization Of The Preparation Process Of Lacticaseibacillus Rhamnosus Microencapsules And Its Characteristics

Probiotics can play beneficial effects such as maintaining the balance of intestinal flora,improving human immunity and reducing cholesterol level.However,the stability of some probiotic strains was not so good,and prone to be affected by adverse environments during transportation,storage,sales and taking to reach the gastrointestinal tract.So,how to improve the stability,bioavailability and resistance to adverse environment in the host digestive tract of probiotics have become one of the major heat points in functional food research.The use of micro-encapsulation technology can improve the resistant properties of probiotics to the adverse external environment,improve the stability and storage stability,reduce the loss in storage and transportation,and extend the shelf life.In this study,Lacticaseibacillus rhamnosus Probio-M9,which has good probiotic properties,was used as the researching object,the microencapsules were prepared by microencapsulation granulator using the complexation of sodium alginate and soybean isolate protein with calcium ions.Its preparation process was determined by optimizing the concentration of sodium alginate,soybean protein isolates,CaCl₂,core-to-wall ratio and pH.Moreover,the morphology,resistance to gastric juice,intestinal solubility,vacuum freeze-drying resistant properties,storage stability of the micaoencapsules were analyzed.This study may provide some data support for the preparation of composite wall microencapsules.The main results are as follows:The optimum processing parameters for the preparation of Lacticaseibacillus rhamnosus microencapsules were obtained by single-factor test and orthogonal test:1.5%sodium alginate,3.0%soybean protein isolates,2.0%CaCl₂,pH 8,and core-to-wall ratio as 1∶1.Under this processing parameters,the embedding rate could reach88.62%.The scanning electron micrographs showed that the prepared microencapsules were round or oval with obvious edge boundaries,firm and smooth surface,no pores and no depressions,the average particle size was around 300μm,and the prepared particles were relatively complete.Lacticaseibacillus rhamnosus microencapsules could completely released by treatment in artificial simulated intestinal juice for 60 min.After digested by artificial simulated gastric juice（pH 2.5）for 2 h,the survival rate of microencapsulated bacteria could sustain 88.65%,with 6.32%higher than that of the unembedded group.After vacuum freeze-drying,the survival rate of the microencapsule group was98.73%,which was 15.45%higher than that of the unembedded group,indicating that the composite wall material played a good protective role for the embedded strains.After 28 d storage at 25℃,the viable count could still reach 9.60×10⁸CFU/m L.Moreover,the number of viable bacteria in the unembedded group was two logarithmic orders lower than that in embedded group,which indicates that microencapsulation can effectively improve the storage stability of the probiotic strain.This study make composite wall material microencapsules by using microencapsule granulator,with mild preparation conditions,high encapsulation yield,good microencapsulation effect,It can lay a foundation for the follow-up research on using composite wall materials to encapsulate live bacteria,and provide certain data support for the development of Lactobacillus microencapsulation technology.