EFFECT OF GRAPE SKIN INCORPORATION ON THE QUALITY OF A DAIRYBASED FROZEN DESSERT

Abstract

The valorisation of winemaking by-products is an important approach for the development of functional foods. This study investigated the effect of grape skin powder (GSP, 0–10%, m/m) incorporation on the quality of a laboratory-scale dairy-based frozen dessert prototype. Five formulations (0, 2.5, 5.0, 7.5 and 10% GSP) were evaluated in terms of physicochemical properties, oxidative stability, colour parameters, microbiological quality and sensory acceptability. Increasing GSP levels led to a progressive decrease in pH (6.72– 5.62) and a slight increase in fat content (26.25–27.66%), while dry matter remained above 54%. Lipid oxidation during frozen storage was reduced in GSP-fortified samples, with peroxide values decreasing from 1.70 meq O₂/kg fat in the control to 1.36 meq O₂/kg fat at 10% GSP after 28 days. Pronounced colour changes were observed (ΔE* = 37–55), associated with grape skin anthocyanins. Functional enrichment was confirmed by increased total polyphenol content (up to 139 mg GAE/100 g) and antioxidant activity (up to 33.6%). Moderate GSP addition (2.5–5.0%) was associated with lower microbial counts, while higher levels introduced additional indigenous microflora. Sensory evaluation indicated good overall acceptability, with the 5% GSP formulation providing the most balanced profile. Overall, grape skin powder shows strong potential as a functional ingredient for dairy-based frozen desserts.