Preparation and characterization of microcapsules using an acid-tolerant sanxan gum combined with sodium alginate/chitosan and their application in Lactobacillus plantarum delivery

The oral delivery of probiotics faces numerous challenges, particularly the acidic gastric environment. This study aimed to construct microcapsules using acid-resistant polysaccharide sanxan gum (SG) combined with sodium alginate (SA) and chitosan (CS), and to evaluate their protective effects on the probiotic bacteria Lactobacillus plantarum ( Lp ) during in vitro simulated gastrointestinal digestion. Sanxan gum, an edible polysaccharide produced by Sphingomonas sanxanigenens strain, is composed of mannose, glucuronic acid, rhamnose, and glucose. Sodium alginate has been widely used to protect probiotics because it is cheap, safe, and easy to form into microcapsules. Chitosan is a cationic polysaccharide with excellent mucoadhesive properties and film-forming capabilities. Herein, the microcapsules were prepared using the extrusion drop method. Compared with microcapsules based solely on sodium alginate, those with a ratio of sanxan gum to sodium alginate of 4:6 demonstrated enhanced encapsulation efficiency (97.66 ± 0.79 %) and freeze-dried cell viability (9.97 ± 0.03 log CFU/g). Furthermore, the incorporation of chitosan yielded the highest encapsulation efficiency for the Lp @SG-SA@CS microcapsules (99.14 ± 1.46 %) and significantly enhanced their tolerance to heat, bile salts, and gastric acid. Our findings suggest that sanxan gum can confer acid resistance to microcapsules, highlighting its potential for applications in diverse acidic environments.