Comprehensive analysis of the effect of etiolated tea cultivars and harvest seasons on volatile compounds and in vitro antioxidant capacity in steamed green teas

Abstract

To explore the effects of harvest seasons and etiolated cultivars on the volatile compounds of steamed green teas, this study analyzed comprehensively the volatile compounds of steamed green teas using simultaneous distillation extraction-gas chromatography–mass spectrometry (SDE-GC–MS) and chemometrics analytical techniques in combination with odor activity value (OAV). Additionally, the in vitro antioxidant capacity of the steamed green teas was evaluated. The results showed that 95 volatile compounds were identified, among which aldehydes, ketones, alcohols, and acids were the main types in steamed green teas made from etiolated tea cultivars. Furthermore, the relative content of volatile compounds in steamed green tea was significantly negatively correlated with season (P < 0.05). In steamed green teas harvested in different seasons, spring tea contained a higher abundance of volatile compounds such as (+)-δ-cadinene, farnesyl acetone, carvenone, trans-β-ionone, and nerolidol. The differences of total volatile compounds among the three etiolated tea cultivars were not remarkable (P > 0.05). Combined with the OAV, 20 and 19 key aroma compounds in steamed green teas from different harvest seasons and cultivars were identified, respectively, which could bring unique aromas to different steamed green tea samples. By comparison, summer tea had the strongest antioxidant capacity, while there was no obvious difference in the antioxidant capacity among cultivars. This study provided a scientific basis for the aroma quality of steamed green teas made from etiolated tea cultivars in different harvest seasons.