Does organic viticulture enhance polyphenol bioaccessibility in syrah grapes and wines? an in vitro and microstructural approach

• Conventional grapes and wines have more content of individual phenolic compounds. • Organic grapes and wines have more bioaccessibility of gallic acid and resveratrol. • Organic agriculture allows for greater bioaccessibility of antioxidant capacity. • Gallic acid is the phenol with the greatest bioaccessibility in grapes and wines. • Organic wine shows lower gastrointestinal degradation of gallic acid and resveratrol. The global consumer trend for more natural, sustainable, and nutritious products has prompted the wine industry to produce grapes and wines from organic systems. The objective of this research was to evaluate the influence of organic agricultural management on the bioaccessibility of phenolic compounds and the antioxidant capacity of Syrah red grapes and wines. This was carried out through an in vitro human digestion simulation (oral, gastric, and intestinal stages) and a microstructural analysis. The conventional vineyard (control) presented a higher content of catechin (grape: 759.94 μg/g, wine: 392.45 μg/g), myricetin (grape: 190.22 μg/g, wine: 110.50 μg/g), and resveratrol (grape: 98.52, wine: 41.33 μg/g). The organic agricultural management contributed to increasing ( p < 0.05) the bioaccessibility index of gallic acid (grape: 17.30 %, wine: 5.86 %), resveratrol (grape: 23.92 %, wine: 14.93 %), and antioxidant capacity (grape: 3.65 %, wine: 19.35 %), which have been widely studied in literature for their positive health impacts (anticancer, anti-inflammatory, cardioprotective). The microstructure exhibited purple, blue, green, orange, and pink hues, indicating the presence of phenols, flavonoids, tannins, and anthocyanins. The findings evidence the potential for bioaccessibility of phenolic compounds and the possible positive health impact of grapes and wines harvested from sustainable systems.