Sustainable valorization of Vitis labrusca L. seeds: optimized phenolic extraction and utilization in antioxidant-enriched yogurt

This study aimed to optimize the extraction of phenolic compounds from Vitis labrusca L . seeds and to evaluate their functional effects in yogurt. A face-centered central composite design under Response Surface Methodology was applied using liquid-to-solid ratio and extraction temperature as variables. Total phenolic content (TPC) and DPPH IC₅₀ were used as response parameters. Optimal conditions yielded 969.30 mg GAE/g TPC and 13.71 mg/mL IC₅₀. The extract was incorporated into yogurt (0.5% and 1.0%, w/w), and physicochemical (pH), microbiological, antioxidant, and sensory properties were evaluated during 14 days of storage. Enriched samples showed significantly higher phenolic content and antioxidant activity compared to control ( p < 0.05), while maintaining microbiological safety and acceptable sensory quality. The 0.5% formulation provided the best balance between functionality and sensory attributes. These findings demonstrate the potential of V. labrusca seed extract as a natural functional ingredient in dairy systems.