Starch-Based Microcapsules of Grape Pomace Phenolics: Physicochemical Characterization and Stability in Static In Vitro Digestion

To protect phenolics of grape pomace, microencapsulation process was carried out with HI-CAP 100, Capsul TA, maltodextrin and potato starch. Encapsulation efficiencies of microcapsules were determined between 69–97%. TPC, TFC, and TAC values of starch-based microcapsules were in the ranges of 36–74 mg GAE/g, 14–28 mg CE/g, and 0.37–0.84 mg C3GE/g, respectively. Maltodextrin, with a value of 74.04 mg GAE/g, was determined to be the best coating material to retain grape pomace phenolics. Similar results were also seen in TFC (28.40 mg CE/g) and ABTS (128.2 mg TE/g) values. While water solubility values were found between 73–92% in microcapsules, grape pomace had 21.81%. The effects of coating materials on the release and bioaccessibility value of grape pomace phenolics encapsulated with different starch types in vitro digestion of oral, gastric and small intestine were investigated. Potato starch-coated microcapsules displayed the least TPC loss in gastric digestion and higher phenolics release in small intestine digestion. The microcapsule with the highest bioaccessibility in oral, gastric, and small intestine phases was Capsul TA, with values of 121%, 205%, and 120%, respectively. Additionally, potato starch-based microencapsulation of phenolics may provide alternative benefits like the slow and balanced release of phenolics in the digestive tract. Microcapsules with maltodextrin, Capsul TA and HI-CAP as coating material had amorphous structures, while potato starch resulted in crystalline structure in the microcapsules. Grape pomace phenolic starch-based microcapsules can be evaluated in the food and pharmaceutical industry depending on the intended use.