This study was designed to find the optimum conditions for isoflavone or beta-galactosidase microencapsulation and to examine the release efficiency of microcapsules in simulated gastrointestinal conditions. Coating materials were either medium-chain triacylglycerol (MCT) or polyglycerol monostearate (PGMS). The highest rate of microencapsulation was found at 15:1 (w/w) ratio of MCT to isoflavone or beta-galactosidase as 70.2 or 75.4%, respectively. When PGMS was used as the coating material, 91.5% beta-galactosidase was microencapsulated with 15:1 mixture (w/w). In vitro study, less than 6.3-9.3% of isoflavone was released in simulated gastric fluid (pH 2-5) during 1 h incubation. Comparatively, isoflavone release increased dramatically to 87.8% at pH 8 for 1 h incubation in simulated intestinal fluid and was maintained thereafter. The release of beta-galactosidase showed a similar trend to that of isoflavone. It appeared in the range of 12.3-15.2% at pH 2-5; however, it increased significantly to 80.6% as the highest value at pH 8. Among the released isoflavones, 53.5% was converted into the aglycone form of isoflavone at pH 8 for 3 h incubation. The present study indicated that isoflavone or beta-galactosidase could be microencapsulated with fatty acid esters and released effectively in simulated intestinal condition.

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