Volatile metabolomics reveals mechanisms of aroma enhancement in green tea via combination drying
Zhibin Ye, Wenjing Huang, Zhenbin Chen, Mengying Zhang, Shengmei Xie, Jixin Zhang, Huan Zhou, Qian Xu, Jingming Ning
Abstract
Drying is key to green tea aroma. Solvent-assisted flavor evaporation–gas chromatography–mass spectrometry and quantitative descriptive analysis were used to characterize the aroma profiles of sun-dried (SD), hot-air-dried (HD), and combination-dried (CD) green tea samples. Sun drying leads to the formation of sweet and floral aromas in green tea, whereas hot-air drying leads to the formation of malty, fatty, and roasted aromas. Gas chromatography–olfactometry and quantitative analysis were used to screen 24 key odorants, with an odor activity value of ≥1, primarily consisting of unsaturated fatty acid degradation products. These products included ( Z )-4-heptenal, ( E )-2-nonenal, ( E , E )-2,4-heptadienal, ( E , E )-2,4-decadienal, 1-octen-3-ol, nonanal, decanal, ( E )-2-octenal, and octanal. Quantitative and in vitro simulation experiments revealed that sun drying mitigated the thermal degradation of unsaturated fatty acids, thereby reducing the production of fatty odorants. The results confirmed that the SD and CD samples had lower fatty odor intensity than the HD sample.