Phenolic Composition and Antioxidant Capacity in Table Grape Berries Following Natural Hail Damage

Phenolic compounds, essential for grape quality, are affected by environmental factors, including abiotic stressors such as hail. This study examined the impact of varying levels of natural hail damage on the physicochemical parameters, phenolic composition, and antioxidant capacity of Thompson seedless grapevines (Vitis vinifera L.) under Mediterranean climatic conditions. The research was carried out in a commercial vineyard in Greece during the 2015 growing season, following a major hailstorm. Three treatments were implemented: control (undamaged), moderate hail damage, and total hail damage. The results showed that pH levels and specific physiological parameters, including proline concentration, were significantly influenced across treatments. Detailed analysis revealed that the concentrations of phenolic compounds generally increased with greater hail damage, indicating enhanced antioxidant capacity and metabolic adaptation to natural hail-induced mechanical stress. Additionally, individual phenolic compounds, such as flavanols, hydroxybenzoic acids, and stilbenes, responded differently to hail damage, demonstrating complex regulatory mechanisms in grape metabolism. These findings underscore the importance of understanding grapevine biochemical responses to extreme weather events in the context of climate change, as changes in phenolic composition can directly affect grape quality.