Probiotics exhibit low viability during food processing and gastrointestinal digestion, which limits their intestinal colonization and the exertion of health-promoting effects. In this study, two food-grade surface coating systems were constructed for Lactobacillus paracasei Li237-MC1 using zein nanoparticles (ZNPs) and Mesona chinensis polysaccharide (MCP) as wall materials, and their application in fermented milk was explored. ZNPs-MC1 and MCP-MC1 were successfully prepared via electrostatic self-assembly and Ca²⁺-mediated cross-linking. Comprehensive characterization techniques confirmed that the coatings were uniform, stable, and biocompatible, without impairing the bacterial activity. Functional evaluations showed that the ZNPs significantly improved the strain’s surface hydrophobicity, thermal stability, and storage stability, while the MCP enhanced acid and bile salt tolerance; both coatings increased the strain’s adhesion to intestinal mucus. When MCP-MC1 was used as an adjunct starter in co-fermented yogurt (LM-Y), it synergized with commercial strains, resulting in the highest viable lactic acid bacteria count (8.72±0.05 Log CFU/mL) at 28 days of storage, the lowest instability index (0.82±0.03), and superior rheological properties. This study provides a novel strategy for improving probiotic stability and expands the application of ZNPs and MCP in functional foods.

Keywords: Probiotics; Coating system; Zein nanoparticles; Mesona chinensis polysaccharide; Yogurt