A Chemical Explanation for Variations in Antioxidant Capacity across Camellia sinensis L. Cultivars

Flavanols are known as the most important antioxidants in tea (Camellia sinensis), but their contribution to the antioxidant capacity across tea cultivars has not been quantified. This study explored whether the variations of antioxidant capacity across tea cultivars could be linked to variations in main flavanol concentrations using 20 widely planted Chinese tea cultivars. The results showed that concentrations of flavanols, both monomeric (total catechins; 3.77%–8.85% d.w.) and polymeric forms (condensed tannins; 9.48%–17.67% d.w.), varied largely across tea cultivars. The contribution of total catechins to the antioxidant capacity in tea (R2 = 0.54–0.55) was greater than that of condensed tannins (R2 = 0.35–0.36) and total phenolic concentrations (R2 = 0.33–0.36). Individual catechin components collectively explained 54.94%–56.03% of the variations in antioxidant capacity across tea cultivars. Epigallocatechin gallate (EGCG) was the leading catechin component that determined the antioxidant capacity in tea (p < 0.001), accounting for up to 57% of the differences in catechin composition between tea cultivars with high and low antioxidant capacities. These results suggested that flavanols were stronger predictors of the antioxidant capacity across tea cultivars compared to total phenolic concentrations, providing guidance for breeding tea cultivars with strong antioxidant capacities.