Valorization of wine industry by-products: Characterization of phenolic profile and investigation of potential healthy properties

In the last years, the importance of food waste management and recovery is emphasized by the international guidelines to promote a circular economy approach. Wine industry is one of the sectors with the highest waste production, with a potential negative environmental impact. Winemaking byproducts are mainly used to produce distillates, fertilizers and livestock feed, but alternative approaches for their management could be the formulation of healthy products. The aim of this study was the application of in vitro methods for a preliminary evaluation of the phenolic pattern and the associated biological properties of winemaking by-products from different red grape varieties. The methods were: 1) Folin-Cocalteau's assay for the assessment of total polyphenol content; 2) the vanillin assay for the quantification of total procyanidin content; 3) the pH differential method for the determination of total anthocyanin content; 4) DPPH and FRAP assays for the measurement of total antioxidant activity; 4) High Performance Thin Layer Chromatography for separation of phenolic substances and assessment of their antioxidant capacity; 5) dipeptidyl peptidase (DPPIV) inhibition assay to evaluate possible effects on glucose homeostasis. The results showed that grape pomace, particularly when including seeds, was a valuable source of polyphenols with significant antioxidant potential and promising activity on DPPIV, supporting its use in formulating healthy foods/food supplements.