Abstract: Beta-lactoglobulin, the main whey protein in bovine milk, has been shown to remain intact in the presence of pepsin and low pH. Skim milk was used as a coating material to improve microencapsulation of Lactobacillus plantarum NCU116 in calcium alginate beads. On the basis of single-factor experiments, the optimization of microencapsulation conditions was carried out using response surface analysis to maximize viable cell count in microcapsules after treatment with artificial gastric fluid. The results showed that the optimal encapsulation conditions were sodium alginate 2.68 g/100 mL, calcium chloride 0.20 mol/L, and skim milk 4.17 g/100 mL. Under these conditions, the particle size of microcapsules, encapsulation rate and viable cell count in microcapsules after treatment with artificial gastric fluid for 3 h were 1.12 mm, 73.49% and 8.79 × 109 CFU/g (close to the theoretical value, 8.85 × 109 CFU/g), respectively. Thus the microencapsulation conditions presented in this study could effectively protect Lactobacillus plantarum from adverse gastric conditions.

Key words: Lactobacillus plantarum NCU116, microencapsulation, simulated gastric fluid, response surface analysis