Changes in volatile compounds in withering tea leaves after infestation with tea green leafhopper (Empoasca onukii Matsuda)

Abstract

The effects of withering, cultivar yellowing, and Empoasca onukii infestation on tea leaf aroma have each been characterized, but variations in volatile compound (VC) contents as a result of co-occurrence of these factors remain unclear. In the present study, we analyzed VC contents in E. onukii-damaged leaves of Camellia sinensis (L.) cv. ‘Yinghong No. 9’ and the yellow bud variant ‘Yellowish Yinghong No. 9’ during the withering process. We found that glycoside-derived volatiles (GDVs) were the most abundant type of VCs, accounting for more than 83% of the total VC content. Linalool formed the main body of the tea aroma, contributing a floral, fruity scent. Differential accumulation of octanal and geranyl acetone in fresh leaves corresponded to differences in the aroma profiles between Yellowish Yinghong No. 9 and Yinghong No. 9. A higher degree of withering did not alter the pleasant aroma odors of Yellowish Yinghong No. 9, but rather maintained the floral, fruity flavors and reduced greenish odors and levels of defense-related compounds (e.g., benzeneacetaldehyde, benzyl nitrile) induced by E. onukii infestation. This study clearly establishes the effects of withering on the aroma profiles of E. onukii-infested leaves in both a standard and a yellow bud mutant tea variety, suggesting a method of maintaining the economic value of even insect-damaged tea leaves.