Abstract: Lactobacillus helveticus MG9-2 was microencapsulated with milk protein as wall material by means of emulsification/internal gelation. The preparation process was optimized, and the effect of different calcium salts (CaCO3 and CaCl2) as crosslinking?agents on microencapsulation efficiency was investigated. The results showed that the optimal process parameters were as follows: stirring speed, 800 r/min; water-to-oil ratio, 1:10; concentration of skim milk, 0.35 g/mL; and concentration of calcium salt, 1.5 mol/L. Under these conditions, the microencapsulation efficiency (ME) of viable cells with CaCO3 and CaCl2 were (78.4 ± 3.6)% and (75.7 ± 4.9)%, respectively, with no significant difference being observed between them. Microcapsules prepared with CaCO3 were smaller in size than those prepared with CaCO3, exhibiting a more compact surface, and a more regular spherical shape and a narrower size distribution and displaying a better resistance to intestinal release and gastric acid. The findings demonstrated that microcapsules with improved properties could be prepared more simply using CaCO3 as crosslinking?agent than CaCl2.

Key words: microencapsulation, Lactobacillus helveticus MG9-2, CaCl2, CaCO3