Microencapsulation of anthocyanins extracted from grape skin by emulsification/internal gelation followed by spray/freeze-drying techniques: Characterization, stability and bioaccessibility

Emulsification/internal gelation is an emerging encapsulation technique with a great potential to protect anthocyanins' stability against the effect of negative environmental conditions. This study aims to microencapsulate anthocyanins extract of grape skin (AEGS) using emulsification/internal gelation associated with spray/freeze-drying techniques. The encapsulation efficiency (EE), particle size and morphology of generated powder microcapsules were further determined. The light (50 W, 5 h) and thermal stabilities (50–90 °C, 2.5 h), as well as in vitro bioaccessibility of microcapsules were evaluated. The results indicated that spray-dried powder microcapsules have smaller median diameter (d50 ≈ 0.56 μm) and better EE of anthocyanins (EE ≈ 75%). Moreover, a series of stability assays revealed that degradation of anthocyanins followed first-order kinetics. However, microencapsulation greatly enhanced light and thermal stabilities of anthocyanins, notably spray-dried microcapsules were the most stable in all assays of this study. The spray-dried microcapsules also showed the lowest degradation constant (0.0207 h−1) and longest half-life (33.47 h) during treatment in the dark. Furthermore, spray-drying favored anthocyanins retention in the microcapsules and improved the prolonged release of anthocyanins in simulated gastrointestinal digestion. These results demonstrated microencapsulation using combined emulsification/internal gelation with drying was feasible for enhancing the stabilization of anthocyanins.