Development of Chocolate-coated Grape Pomace Extrudates with Enhanced Antioxidant Activity and Sensory Acceptability

Abstract

Transforming agro-industrial waste into gourmet functional foods offers a dual solution to environmental sustainability and consumer nutrition. This study valorizes grape pomace and okara, nutrient-dense by-products of the wine and soy-milk industries into a high-fiber, protein-rich extruded snack. To bridge the gap between “healthy” and “highly acceptable,” we evaluated the impact of a milk chocolate coating on the snack’s physicochemical and sensory profile compared to uncoated samples. Using a completely randomized design (CRD) and paired t-tests for analysis, results revealed that, moisture and ash remained stable, the chocolate coating significantly balanced the product’s profile by increasing pH from 4.69 to 5.33 and reducing titratable acidity from 0.74% to 0.40%. While fat content increased due to the cocoa butter and milk fat, the structural integrity of the extrudates remained intact. Most notably, the coating triggered a synergistic boost in antioxidant activity, despite non-significant changes in total phenolic content, the significant rise in antioxidant activity suggests a powerful interaction between grape and cocoa polyphenols. Sensory results confirmed a marked improvement in overall acceptability, proving that chocolate coating is not just an additive, but a strategic tool to transform industrial by-products into value-added, market-ready functional delicacies.