Stable and Functional Cosmetic Creams Enriched with Grape Stem Extract: A Sustainable Skincare Strategy

The growing demand for sustainable and effective cosmetic ingredients has prompted renewed interest in winemaking by-products. Among these, grape stem (GS) extract remains relatively underexplored despite its rich content of phenolic compounds distinct from those found in more commonly studied grape seeds or skins. This study validates the potential of GS extract as a novel bioactive component in cosmetic cream formulations. Rich in antioxidant, antiaging, and depigmenting compounds-such as resveratrol, catechins, and phenolic acids-GS extract was incorporated into creams at concentrations ranging from 0.33% to 6.25%. The formulations were evaluated for physicochemical characteristics, texture, rheological behaviour, and biological activity. The results demonstrated that GS extract enhanced total phenolic and flavonoid content, as well as viscosity, firmness, and antioxidant capacity-although not always in a concentration-dependent manner. All formulations maintained appropriate pH values and microbiological stability. Accelerated stability tests (40 °C, 75% RH, 3 months) identified the 0.83% to 1.64% concentration range as the most stable, preserving phenolic content, viscosity, and bioactivity. Higher extract levels, in contrast, led to reduced formulation stability, coalescence, and diminished antioxidant performance over time. Notably, GS-enriched creams exhibited significant elastase and tyrosinase inhibition, with lower concentrations maintaining antiaging potential throughout storage. These findings not only demonstrate that the incorporation of GS extract into a cosmetic base preserves its biological functionality but also reinforce the unique value of grape stems as an untapped resource for cosmetic innovation. Overall, the study advances current knowledge by establishing formulation parameters for a stable, effective, and sustainable cream based on grape stem extract. Further studies are recommended to optimize extract concentration and investigate encapsulation strategies for enhanced bioactive delivery and long-term stability.