The wine industry, a major player in the global agri-food sector, generates millions of tonnes of grape pomace annually as a by-product. Although rich in polyphenols, fiber, and antioxidants with proven health benefits, most pomace remains underutilized, often being discarded or repurposed as low-value compost or animal feed. This study highlights the untapped potential of grape pomace flour by analyzing its bioactive profile, emphasizing its viability for high-value applications in nutraceuticals, functional foods, and pharmaceuticals.

Six samples from two Portuguese grape varieties (Arinto and Touriga Nacional) were sourced from three wineries (Carmim, Cerrado da Porta, Mingorra) and analyzed. Total phenolic content (114.94–128.31 mg GAE/100 g) and flavonoids (452.74–2,214.27 mg quercetin equivalents/100 g) were quantified spectrophotometrically, demonstrating potent antioxidant activity (FRAP: 110.56–543.00 µmol FeSO₄/100 g; DPPH: 586.93–698.71 µmol Trolox/100 g). Dietary fiber stood out (45.29–64.97%), surpassing many conventional sources, while HPLC analysis confirmed B-vitamins and calculated macronutrient profiles.

The findings reveal grape pomace as a sustainable, nutrient-dense ingredient. In food production, it could enrich baked goods, snacks, or supplements, leveraging its fiber for gut health and its polyphenols for oxidative stress reduction. Cosmetic applications include anti-aging serums, harnessing their free radical-scavenging properties. Pharmaceutical uses extend to anti-inflammatory formulations or controlled-release delivery systems, with emerging research supporting its role in mitigating metabolic syndrome and cognitive decline.

By transforming waste into value-added products, this approach aligns with circular economy principles, reducing environmental impact while creating new revenue streams for wineries. Further research should optimize extraction methods and evaluate bioavailability to maximize commercial adoption.