Abstract:A composite probiotic microencapsulation system based on whey protein and Dendrobium polysaccharide was prepared, and the effects of whey protein concentration, Dendrobium polysaccharide concentration and curing time on encapsulation were investigated using single-factor experiments; the formulation was optimized by response surface methodology (RSM), and the protective effect of the microcapsules was evaluated through in vitro simulated gastrointestinal digestion. The optimal formulation was determined as Dendrobium polysaccharide 0.8 %, whey protein 2 % and curing time 1 h, under which the viable count of the microencapsulated probiotics reached up to 1.80×10⁹ CFU/mL, and the validation experiment gave 1.75×10⁹ CFU/mL. With comparable initial viable counts (ca. 2.9×10⁸ CFU/mL), after 3 h in simulated gastric fluid the encapsulated group remained 6.31×10⁵ CFU/mL (survival ca. 0.22 %, log reduction 2.67) versus 8.51×10³ CFU/mL (survival ca. 0.003 %, log reduction 4.53) for the free cells; after 3 h in simulated intestinal fluid the encapsulated group maintained 2.51×10⁷ CFU/mL (survival ca. 8.6 %, log reduction 1.07) versus 1.07×10⁵ CFU/mL (survival ca. 0.037 %, log reduction 3.43) for the free cells. The encapsulated group showed significantly higher survival than the free cells at each time point (P<0.05). The composite wall material could improve the in vitro gastrointestinal tolerance of probiotics.