Abstract: Spray-dried microencapsulated anthocyanins were prepared by emulsification/internal gelation with sodium alginate as the wall material. The drying process was optimized. The particle size and morphology of anthocyanin microcapsules were investigated. The stability of native and microencapsulated anthocyanins against light, temperature and gastrointestinal digestion was also evaluated. The optimal process parameters were determined as follows: heater temperature of 120 ℃, feeding rate of 12 r/min, and vacuum pressure of 0.03 MPa, giving a microencapsulation rate of 75.12% and an average particle size of 558.2 nm. The preservation rates of free and microencapsulated anthocyanins were 63.7% and 82.1%, respectively, after being kept for 5 h in light compared to 78.6% and 91.4% in darkness. The half-life of free anthocyanins was 2.54 h at 90 ℃ while that of anthocyanin microcapsules was 6.39 h. After gastric digestion for 2 h, the retention rates of free and microencapsulated anthocyanins were 45.3% and 83.7%, respectively; the retention rate of free anthocyanins was only 0.9% after intestinal digestion for 4 h while that of anthocyanin microcapsules was as high as 24.4%. These results demonstrated that the anthocyanin microcapsules were more stable against light, temperature and gastrointestinal digestion than the free ones.

Key words: anthocyanins, microcapsule, emulsification/internal gelation, spray drying, stability