Development of a Wine By-Product-Based Beverage and Study of Its Potential to Postprandial Glycemia Regulation in Healthy Individuals: A Proof of Concept Study.

Aligned with the principles of the circular bioeconomy, this study explores the use of winemaking by-products as a source of bioactive phenolic compounds. Skins and seeds from Tempranillo and Graciano grapevine varieties were conditioned to prepare a phenolic-rich beverage. To study its hypoglycemic properties, a pilot trial was conducted to evaluate postprandial glycemia after the intake of the wine by-product-based beverage (WBB). The postprandial glycemia of 10 healthy adults was measured after the intake of: (i) water + sugar solution, (ii) WBB + sugar solution, and (iii) WBB + water. In parallel to blood glucose measurement, blood samples were also collected using dried blood spot cards to determine the phenolic metabolites by UHPLC-QqQ-MS/MS. Although blood glucose levels tended to decrease after WBB intervention, these changes were not statistically significant related to the interindividual variability. The volunteers showing a reduction in blood glucose were classified as "responders", and those who showed no changes were classified as "non-responders". Wine by-products can be effectively used in functional beverages formulation to increase bioactive compound content and manage postprandial glucose in some individuals.