Characterization of Grape Pomace Extract Microcapsules: The Influence of Carbohydrate Co-Coating on the Stabilization of Goat Whey Protein as a Primary Coating

Both grape pomace and whey are waste products from the food industry that are rich in valuable ingredients. The utilization of these two by-products is becoming increasingly possible as consumer awareness of upcycling increases. The biological activities of grape pomace extract (GPE) are diverse and depend on its bioavailability, which is influenced by processes in the digestive system. In this work, goat whey protein (GW) was used as the primary coating to protect the phenolic compounds of GPE during the spray drying process. In addition, trehalose (T), sucrose (S), xylose (X), and maltodextrin (MD) were added to the goat whey proteins as co-coatings and protein stabilizers. All spray drying experiments resulted in microcapsules (MC) with a high encapsulation efficiency (77.6-95.5%) and yield (91.5-99.0%) and almost 100% recovery of phenolic compounds during the release test. For o-coumaric acid, the GW-coated microcapsules (MC) showed a bioavailability index of up to 731.23%. A semi-crystalline structure and hydrophilicity were characteristics of the MC coated with 10% T, S, X, or 5% MD. GW alone or in combination with T, S, MD, or X proved to be a promising carrier for polyphenols from grape pomace extract and ensured good bioavailability of these natural antioxidants.