## 2 Results  
### The Volatile Profiles of Green Teas Prepared from Different Cultivars  
Figure 1 shows the pictures of green teas, black teas, and the corresponding freeze-dried tea samples prepared from five tea cultivars, namely 'Chunyu2', 'Chunyu1', 'Jinguanyin', 'Zhenong117', and 'Longjing43'. The sensory evaluation of these green and black teas was carried out by an evaluation panel, and the comprehensive evaluation results are shown in Table S1. Based on the description of aroma (Table S1, see Supplementary Materials), 'Chunyu2' green tea was identified as a long-lasting lily of valley of fragrance, and 'Jinguanyin' was identified as a long-lasting rose fragrance, which was clearly discriminated from other green teas with no floral fragrance (Figure 1). The volatile compositions of different green teas are shown in Table S2. A total of 68 volatiles were annotated and quantified in different green teas, including 26 alcohols, 12 aldehydes, 7 ketones, 11 esters, 1 pyrrole, and 11 miscellaneous. 'Chunyu2' green tea contained the highest content of total volatiles at 134.75 \(\upmu\)g guaiacol equivalent (GE)/g dry tea, subsequently followed by 'Jinguanyin' (82.65 \(\upmu\)g GE/g), while 'Zhenong117', 'Longjing43', and 'Chunyu1' contained relatively low contents of total volatiles ranging from 50.57 to 65.14 \(\upmu\)g GE/g. For all the green teas, alcohols were the major type of volatiles in green teas accounting for 44.2-66.9% of total volatiles, among which 'Chunyu2' contained the highest content of total alcohols at 90.21 \(\upmu\)g GE/g, followed by 'Jinguanyin' (48.34 \(\upmu\)g GE/g), while 'Zhenong117',  
'Longjing43', and 'Chunyu1' contained the relatively low contents of total alcohols ranging from 22.45 to 29.97 \(\upmu\)g GE/g. Moreover, 'Chunyu1', 'Zhenong117', and 'Longjing43' contained higher proportions of total aldehydes (14.6-23.0%) than those of 'Chunyu2' and 'Jinguyin' (6.5% and 9.7%). The highest level of total esters (17.34 \(\upmu\)g GE/g) was observed in 'Chunyu2', corresponding to 12.9% of total volatiles, followed by 'Zhenong117' (9.67 \(\upmu\)g GE/g), while 'Chunyu1', 'Jinguyin', and 'Longjing43' had relatively low levels of total esters ranging from 3.28 to 4.86 \(\upmu\)g GE/g. Hence, the green tea samples prepared from different tea cultivars had different volatile profiles. Figure 2 shows the hierarchically clustered heatmap of the relative contents of 68 volatile compounds in different green teas. These five green teas were clustered into two main groups: the first main group of 'Jinguyin' and 'Chunyu2' green teas and the second main group of 'Chunyu1', 'Zhenong117', and 'Longjing43' green teas, which was consistent with the aroma features according to the result of sensory evaluation. Among these five green tea samples, 'Jinguyin' and 'Chunyu2' are the green tea samples with floral stents. Further, the second main group was clustered into two subgroups, viz. 'Chunyu1' and the group of 'Zhenong117' and 'Longjing43'. Based on the composition of alcohols (the insert of Figure 2, alcohols), 'Jinguyin' and 'Chunyu2' green teas were clustered and discriminated from the other three cultivars; however, the heatmaps of alcohol compositions were different between 'Jinguyin' and 'Chunyu2' green teas that had their own characteristic odorants. Based on the composition of esters (an insert of Figure 2, esters), 'Chunyu2' green tea was discriminated from the other four cultivars due to the relatively higher contents of methyl 2-methyl-3-oxobutanoate, dibutyl benzene-1,2-dicarboxylate, and [(Z)-hex-3-enyl] hexanoate. For aldehydes and ketones, 'Longjing43' green tea was discriminated from other cultivars. Figure 1: Pictures of freeze-dried samples, green, and black teas from different tea cultivars and their identified scent type. One-third of the harvested fresh tea leaves were freeze-dried immediately, while the remaining two-thirds were divided into two fractions for green and black tea preparation, respectively.