Influence of roasted grape seed infusion on the sensory profile of Merlot red wine during aging

In the context of the agroecological transition and the need to valorize winery by-products, grape seeds - naturally rich in tannins and aroma precursors - represent a sustainable alternative to traditional oak. Seeds collected after fermentation of a 2022 Merlot (Bordeaux) were dried and roasted according to five controlled thermal profiles (T1-T5) ranging from light to intense treatment, and were then used to infuse wine. Sensory evaluations of both roasted seeds and infused wines (1 g/L for 14 days) were performed by a panel of eight trained tasters. Roasting significantly altered the seeds' aroma, generating descriptors ranging from popcorn (T1) and nutty (T2) to chocolate (T3), coffee (T4), and smoky notes (T5). Wines infused with roasted seeds could be clearly differentiated from the control (p < 0.001) and exhibited aromatic profiles closely reflecting those of the corresponding seeds. Treated wines showed greater sensory complexity and improved mouthfeel, indicating that roasted grape seeds are a promising grape-derived alternative to oak, thus supporting circularity in winemaking. • Roasted grape seed infusion is a sustainable innovation for red wine aging. • Roasting grape seeds has a strong sensory impact on wine aroma and taste. • The aromatic profile evolves from popcorn to coffee as roasting intensity increases. • Seed infusion enhances complexity in wines aged without oak. • Upcycling roasted seeds, a grape by-product, enriches the wine tasting experience.