Valorizing Red Grape Pomace through the Development of Biscuits with Potential Health-Promoting Properties

Long-term adherence to a dietary pattern rich in polyphenols with proven cardiometabolic benefits remains challenging for the general population. In this study, red grape pomace (GP), an agro-industrial by-product, was incorporated into biscuits as a sustainable ingredient to enhance dietary polyphenol intake. Crude crushed GP was added to a control (CTR) biscuit formulation at 20% and 30% (w/w), improving the nutritional profile by increasing dietary fiber while reducing lipid and energy contents. The enriched biscuits provided up to 540 mg GAE of total polyphenols per 100 g.

In addition to anthocyanins, GP supplied flavonoids and grape seed procyanidins, which contributed to the high antioxidant capacity of the 20-GP and 30-GP biscuits. Following in vitro gastro-duodenal digestion, both GP-enriched formulations exhibited significantly lower concentrations of reducing sugars than the CTR biscuits, suggesting that the combined effects of GP fiber and polyphenols may slow glucose release and intestinal absorption.

A total of 60 volatile compounds were identified in the biscuits. Notably, GP-enriched biscuits contained lower levels of Maillard reaction products than the CTR formulation, likely owing to the free radical-scavenging activity of grape polyphenols. Despite the relatively high GP incorporation levels, sensory attributes and overall consumer acceptance—particularly for the 20-GP biscuits—were largely preserved.

Overall, these findings demonstrate that red grape pomace can be successfully valorized as a functional food ingredient, improving the nutritional and bioactive profile of biscuits while maintaining acceptable sensory quality. This work provides a basis for future nutritional studies investigating the health-promoting potential of GP-enriched biscuits and supports the sustainable large-scale production of foods that transform an agro-industrial waste into a value-added resource.