Abstract
Grape pomace extract (GPE), a polyphenol- and mineral-rich winery by-product, was incorporated (0–8%, w/w) into dark chocolate, following evaluation of the mineral content, physicochemical and rheological properties of the final product. Ultrasound-assisted extraction yielded a phenolic-rich extract with total phenolic content equal to 32.51 ± 2.1 mg GAE mL− 1 . GPE incorporation resulted in a significant (p < 0.05) dose-dependent increase in both macro- and trace elements, with marked enrichment in K, Mg, Ca, and Fe, indicating efficient transfer and retention of pomace-derived minerals within the chocolate matrix. At incorporation levels of 1–8% (w/w), GPE decreased the pH of the chocolate and increased titratable acidity, moisture content, and water activity, indicating the contribution of acidic and hydrophilic pomace-derived constituents. These compositional changes were translated into pronounced modifications of the product flow behavior. Rheological analysis showed increases in yield stress and plastic viscosity, with Herschel-Bulkley yield stress rising from 7.2 to 12.8 Pa and consistency index nearly doubling, accompanied by enhanced shear-thinning behavior. Rheological reinforcement of the fat-mediated dispersion network peaked at 6% (w/w) GPE, with a slight reversal of this trend at 8% (w/w), suggesting the onset of structural heterogeneity, while sensory deterioration became statistically detectable from 2% (w/w) onward, the magnitude of decline increased sharply from 4% (w/w). Color and sensory analyses confirmed that while low-to-moderate GPE incorporation (1–2% w/w) preserved typical chocolate attributes,. The results highlight the critical balance between nutritional enhancement and colloidal stability in fat-based confectionery systems enriched with plant-derived extracts.