Influence of Seasonal and Yearly Variation on Phenolic Profiles, Caffeine, and Antioxidant Activities of Green Tea (Camellia sinensis (L.) Kuntze) from Azores

This study compares the antioxidant properties (RSADPPH–DPPH radical scavenging activity, FRAP–ferric reducing activity power, and FIC–ferrous ion-chelating activity), total phenolics (TP), flavonoids (TF), catechin profiles, as well caffeine content of Azorean Camellia sinensis green tea collected in seasons two different years. The RSADPPH showed some variation between 2019 2020, presented, general, better results 2020 during summer seasons. FRAP was also noted to be at its highest July August investigated years (6.64 6.40 µg/mL 5.85 5.46 2020). According FIC sample exhibited value (76.18%). TP varied 291.14 326.93 mg gallic acid equivalents (GAE)/g dried extract (DE) 300.25 320.58 GAE/g DE 2020. Concerning TF, values 51.85 67.93 rutin (RE)/g 50.27 69.57 RE/g Epicatechins derivatives, determined by HPLC, presented higher all samples from compared 2019, same observed for esterified catechins. epigallocatechin-3-gallate (214.52–240.16 mg/g DE) (140.91–210.83 DE). Regarding (12.86–20.45 13.19–29.35 2020), April June similar both In than with exception while TF contents certain months reflect impact climatic on quality.