## 2 Results
### The Volatile Profiles of Black Teas Prepared from Different Cultivars  
'Jinguanyin' black tea was identified as a long-lasting rose fragrance with a sweet aroma; the floral aroma of 'Chunyu2' black tea was not as intense as 'Jinguanyin' black tea, while other black teas had no floral fragrance (Figure 1 and Table S1). Table S3 shows the volatile compositions of different black teas. A total of 70 volatiles were annotated and quantified in different black teas, including 24 alcohols, 18 aldehydes, 6 ketones, 7 esters, 3 acids, 1 pyrrole, and 11 miscellaneous. 'Jinguanyin' black tea contained the highest content of total volatiles (1008.05 ug GE/g), subsequently followed by 'Chunyu2' (1251.56 ug GE/g), while 'Zhenong117', 'Longjing43', and 'Chunyu1' contained relatively low contents of total volatiles (600.20 to 763.88 ug GE/g). Alcohols were the most abundant volatiles in black teas, accounting for 60.9-77.2% of total volatiles, which was the same as green teas. Specifically, 'Jinguanyin' contained the most abundant total alcohols at 1204.65 ug GE/g, followed by 'Chunyu2' (965.82 ug GE/g), whereas 'Zhenong117', 'Longjing43', and 'Chunyu1' contained the relatively low contents of total alcohols (365.99-511.86 ug GE/g). 'Jinguanyin' contained the highest contents of total aldehydes and total esters, being 308.03 and 128.68 ug GE/g, respectively, which were much higher than those of 'Chunyu1', 'Zhenong117', 'Longjing43', and 'Chunyu2'. Figure 4 shows the hierarchically clustered heatmap of the relative contents of these 70 volatile compounds in different black teas. These five black teas were divided into two main groups: the first group of 'Jinguanyin' and the second group consisting of 'Chunyu2', 'Chunyu1', 'Longjing43', and 'Zhenong117'. Then, the second group was further divided into two main subgroups: 'Chunyu2' and the others. 'Chunyu2' black tea had a higher similarity to 'Jinguanyin' black tea compared with other samples. This was also consistent with their aroma features, as indicated in Figure 1. The abundant presence of five alcohol compounds, including (6E)-3,7,11-trimethyldodeca-1,6,10-trien-3-ol, (15,4R)-1,6-dimethyl-4-propan-2-yl-3,4a,7,8,8a-hexahydro-2H-naphthalene-1-ol, (15,2R,55,7R,8R)-2,6,6,8-tetramethyltricyclo[5,3.1.01,5]undecan-8-ol, (2E)-3,7-dimethylocta-2,6-dien-1-ol, and dodecan-1-ol, four ester compounds, including 1-O-(2-methylpropyl) 4-\(O\)-propan-2-yl 2,2-dimethyl-3-propan-2-ylbutanedioate, methyl hexadecanoate, bis(2-methylpropyl) benzene  
Figure 3: The PCA result of green tea samples from different tea cultivars based on the volatile compositions. (**A**) score plot; (**B**) loading plot. The number of replicates is equal to 3. 1,2-dicarboxylate, and diethyl benzene-1,2-dicarboxylate, as well as seven aldehyde compounds, including (2Z)-3,7-dimethylocta-2,6-dienal, (2E)-3,7-dimethylocta-2,6-dienal, 7,7-dimethoxyheptanal, 2,4-dimethylbenzaldehyde, (4E,8E)-5,9,13-trimethyltetradeca-4,8,12-trirenal, nonanal, and decanal importantly contributed to the aroma characteristics of 'Jinguanyin' black tea distinguished from other black teas. Belonging to the same subgroup of alcohols with 'Jinguanyin' black tea, 'Chunyuz' black tea was rich in 6-ethenyl-2,2,6-trimethyloxan-3-ol, heptan-2-ol, 2-[(2S,55)-5-ethenyl-5-methyloxolan-2-yl]propanan-2-ol, 3,7-dimethylocta-1,6-dien-3-ol, and 2-[(1S)-4-methylcyclohex-3-en-1-yl]propanan-2-ol. For aldehydes, ketones, and esters, 'Jinguanyin' black tea was discriminated from other black teas. Figure 5 shows the PCA score plot and loading plot of different black tea samples based on the compositions of volatiles. The first three principal components (PC) accounted for 82.0% of the total variance (PC1 = 44.1%, PC2 = 21.7%, PC3 = 16.2%). Clearly, the black teas of the same cultivar were clustered well and discriminated from each other.