Portuguese Wine Grape Skins and Their Applications in Cereal Bars: A Literature Review

The Portuguese vinifera grape’s skins are by-products of the wine industry with a high content of bioactive compounds such as flavonoids, anthocyanins, dietary fiber, and minerals. This chapter presents a narrative review of their nutritional and functional properties, as well as the feasibility of incorporating them into cereal bars. The quality of the skin is influenced by factors such as grape variety, terroir, climatic conditions, and the degree of ripeness, which determine the concentration of the phenolic compounds and their antioxidant potential. The usage of these skins in the formulation of the cereal bars contributes to the nutritional enrichment, improvement of sensory characteristics, and extension of the shelf life of the product, in addition to reducing the disposal of agroindustrial waste, favoring the circular economy. Despite technological challenges related to the standardization and stability of the ingredient, studies indicate good technical feasibility and sensory acceptance. Thus, the incorporation of wine grape skins in cereal bars emerges as an innovative and sustainable strategy for the development of functional foods, combining health benefits and the valorization of wine-making by-products.