关键词: 湘西黄金茶；烘青绿茶；茶树品种；顶空固相微萃取-气相色谱-质谱联用；随机森林

Abstract: In order to tap into the advantages of Xiangxi Huangjincha variety resources and distinguish Huangjincha green tea from baked green tea from other cultivars, headspace-solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) and chemometrics were utilized to compare the differences in key volatile compounds among Huangjincha 1 (HJC), Bixiangzao (BXZ), and Fuding Dabai (FDDB) baked green teas from different production areas in Xiangxi Prefecture. Moreover, a discriminant model was constructed using random forest. The results of sensory evaluation showed that the aroma profiles of 39 baked green tea samples were dominated by clean and chestnut-like aromas. HS-SPME-GC-MS analysis identified a total of 161 volatile compounds. The contents of total volatile compounds, alcohols, and esters in HJC were significantly higher than those in BXZ and FDDB (P < 0.05). Using the cutoff of variable importance in the projection (VIP) > 1, P < 0.05 and fold change (FC) ≥ 2 or ≤ 0.5, 23 key differential volatile compounds that could distinguish HJC from BXZ and FDDB were selected by chemometrics. The random forest model constructed based on the selected volatile compounds could discriminate HJC from non-HJC green tea accurately. Moreover, terpenoids and their derivatives such as geraniol and α-terpineol were considered potential biomarkers of HJC. The research results can provide a theoretical basis for the quality control and industrial development of Xiangxi Huangjincha.

Key words: Xiangxi Huangjincha; baked green tea; tea cultivars; head space-solid phase microextraction combined with gas chromatography-mass spectrometry; random forest