Figures (5)  Tables (1)

    • Figure 1. 

      Geographical distribution of 31 tea cultivars. * Map lines delineate study areas and do not necessarily depict accepted national boundaries.

    • Figure 2. 

      GC-MS analysis of volatile compounds in GT and OT. (a) The proportion of volatile compounds in the total components. (b) Venn diagram of the volatile compounds of GT and OT. (c) Total amount of different volatile compound categories in GT and OT (different letters indicate significant differences, p < 0.05, GT: n = 15; OT: n = 16).

    • Figure 3. 

      Multivariate analysis of volatile compounds and screening of differential volatile compounds. (a) Score plots for the PCA analysis of the volatile compounds. (b) Score plots for the OPLS-DA analysis of the volatile compounds. (c), (d) OPLS-DA model validation and 200 permutation tests. (e) Scatter plot of differential volatile compounds. (VIP > 1, p < 0.05). (f) The Venn diagram of differential volatile metabolites between GT and OT.

    • Figure 4. 

      Random forest analysis and ROC curve of differential volatile compounds between GT and OT. (a) Ranking of mean decrease accuracy, the higher the accuracy, the greater the importance of the metabolite, and the top 10 compounds were selected for display. (b) The ROC curve was used to assess the performance of the random forest classifier. (c) ROC curve assessment of the top 10 key compounds.

    • Figure 5. 

      Heatmap of volatile compounds across different varieties and flavor wheel of aromatic compounds. (a) Heatmap analysis of key volatile compounds selected across different cultivars. (b) Flavor wheel of eight key volatile compounds in GT and OT (rOAV > 1).

    • Category RT RI Compounds Content (μg/L) Threshold
      (μg/L)      		 Odor characteristics
      GT OT
      Aldehyde
      1 6.390 796 Hexanal 116.98 ± 13.97 a 25.14 ± 0.44 b 4.5A Grassy, green, leafy, vinegar
      2 10.210 902 Heptanal 262.74 ± 11.05 a 25.92 ± 1.28 b 2.8C Faint scent, herbal, citrusy
      3 12.449 960 Benzaldehyde 1,008.64 ± 144.59 a 67.81 ± 10.30 b 350C Sweet, bitter, almond, cherry
      4 12.562 962 1,2-Benzenedicarboxaldehyde 711.78 ± 35.67 a 2.60 ± 0.21 b 1,000F Mild, aromatic
      5 14.105 1,002 Octanal 88.24 ± 1.90 a 16.17 ± 1.09 b 7A Citrusy, fruity, waxy
      6 17.921 1,103 Nonanal 578.00 ± 7.10 a 40.67 ± 1.30 b 1F Citrus, orange, peel
      7 21.577 1,204 Decanal 114.07 ± 10.61 a 24.33 ± 0.87 b 2.6A Citrusy, waxy
      8 21.987 1216 β-Cyclocitral 160.36 ± 2.49 a 15.46 ± 1.23 b 3A Lemon, citrus, floral
      9 23.887 1,272 4-Propyl-benzaldehyde 268.71 ± 3.44 a 63.65 ± 0.72 b 10F Floral, almond
      10 28.276 1,407 Dodecanal 98.92 ± 17.18 a 7.27 ± 0.39 b 14F Citrusy, waxy, fruity, fatty
      11 28.277 1,408 Tridecanal 91.29 ± 1.28 a 2.81 ± 0.37 b 70F Citrus, faint scent, soapy
      12 36.369 1,686 3-Methyl-butanal 27.11 ± 4.59 a 0.56 ± 0.01 b 0.1B Pungent, fruity, nutty
      13 41.828 1,900 Pentadecanal 123.51 ± 6.32 a 17.79 ± 0.65 b 430F Waxy, fatty, floral
      Ester
      14 9.086 871 Hexyl formate 19.91 ± 1.18 a 2.35 ± 0.23 b 0.1F Fruity
      15 13.394 984 Vinyl hexanoate 39.90 ± 1.49 a 1.01 ± 0.30 b 50F Faint scent, fruity
      16 13.690 992 Geranyl butyrate 318.80 ± 12.74 a 13.80 ± 0.36 b 0.1F Sweet, fruity, floral, orange
      17 13.883 997 Ethyl hexanoate 26.88 ± 3.34 a 0 b 5A Fruity, sweet, faint scent
      18 17.581 1,094 Benzyl acetate 15.66 ± 1.04 a 0 b 364G Sweet, floral, fruity, balsamic
      19 20.838 1,184 Z-3-Hexenyl butyrate 295.40 ± 6.60 a 35.37 ± 2.14 b 0.1F Faint scent, fruity, green, sweet
      20 21.082 1,190 Methyl salicylate 17022.62 ± 975.42 a 2071.62 ± 116.92 b 40A Caramel, minty, herbal
      21 23.102 1,249 Geranyl isovalerate 2,777.80 ± 77.04 b 6,117.11 ± 153.55 a 100F Floral, fruity, herbal, citrus
      22 26.122 1,339 Acetyleugenol 29.22 ± 1.75 a 5.02 ± 0.83 b n.f. Spicy, sweet, fruity, woody
      23 26.440 1,349 Cinnamyl isovalerate 44.19 ± 6.57 a 1.35 ± 0.08 b n.f. Sweet, spicy, fruity
      24 27.031 1,368 Hexyl hexanoate 28.89 ± 1.07 a 1.52 ± 0.09 b 6,400A Fruity, sweet, creamy
      25 27.322 1,377 4Z-4-Hexenyl butyrate 304.75 ± 14.37 a 1.47 ± 0.09 b n.f. Fruity, sweet, faint scent, apple
      26 27.337 1,378 Neryl hexanoate 232.94 ± 2.00 a 17.08 ± 1.46 b 781C Fruity, green, pear, pineapple
      27 27.590 1,385 E-2-Hexenyl hexanoate 16.36 ± 2.75 a 0.91 ± 0.10 b n.f. Fruity, sweet
      28 33.074 1,568 Nerol benzoate 152.34 ± 2.19 a 51.13 ± 2.35 b 500C Faint scent, floral
      29 33.531 1,584 2,2,4-Trimethyl-1,3-pentanediol diisobutyrate 37.89 ± 1.07 a 0 b n.f. Mild, sweet, fatty
      30 33.737 1,591 Ethyl laurate 35.88 ± 5.61 a 3.56 ± 0.56 b n.f. Sweet, fruity, fatty
      31 34.710 1,626 Decyl decanoate 131.49 ± 21.24 a 20.23 ± 0.88 b n.f. Mild, fatty, oily
      32 39.104 1,791 Ethyl tetradecanoate 46.03 ± 3.72 a 17.34 ± 0.55 b 4,000F Sweet, fatty, fruity
      33 42.374 1,922 Methyl palmitate 70.55 ± 1.01 a 8.60 ± 0.65 b 2,000E Waxy, sweet
      34 44.065 1,990 Ethyl palmitate 555.70 ± 1.19 a 171.98 ± 5.31 b 2,000E Mild, fatty
      35 46.868 2,061 Phytyl acetate 270.72 ± 24.58 a 11.79 ± 2.61 b 2C Floral, green, faint scent
      36 47.879 2,085 Ethyl linolenate 214.69 ± 16.09 a 63.76 ± 0.48 b 450G Oily, fatty, nutty, green
      Alkane
      37 14.034 1,001 3,6-Dimethyldecane 14.24 ± 0.45 a 0 b n.f. Mild, fatty, hydrocarbon
      38 14.678 1,017 Undecane 40.26 ± 1.81 a 0 b 10,000E Odorless, oily, waxy
      39 16.129 1,056 5-(2-Methylpropyl)-nonane 137.29 ± 23.92 a 19.82 ± 0.10 b n.f. Mild, fatty, hydrocarbon
      40 16.131 1,057 3-Ethyl-3-methyl-heptane 64.16 ± 3.05 a 19.70 ± 1.46 b n.f. Mild, fatty, hydrocarbon
      41 16.199 1,058 2,3,5,8-Tetramethyl-decane 176.24 ± 10.97 a 8.25 ± 0.86 b n.f. Odorless, oily
      42 16.335 1,061 3,7-Dimethyl-decane 66.14 ± 1.73 a 0 b n.f. Odorless, oily
      43 21.429 1,200 Dodecane 376.64 ± 23.67 a 49.92 ± 3.52 b 1000E Mild, hydrocarbon, petroleum
      44 21.733 1,209 3,4-Dimethyl-undecane 31.33 ± 2.28 a 2.29 ± 0.07 b n.f. Odorless
      45 23.539 1,262 3-Ethyl-3-methyl-decane 52.59 ± 3.52 a 10.34 ± 0.95 b n.f. Mild, hydrocarbon
      46 23.989 1,275 4,6-Dimethyl-dodecane 582.01 ± 80.64 a 86.94 ± 0.96 b n.f. Odorless, oily
      47 24.257 1,283 5-Butyl-nonane 95.06 ± 17.35 a 0.49 ± 0.10 b n.f. Odorless
      48 26.890 1,371 2,6,10-Trimethylpentadecane 69.46 ± 1.95 a 5.41 ± 0.32 b n.f. Oily,waxy
      49 28.047 1,399 Tetradecane 339.47 ± 33.31 a 48.08 ± 0.89 b 1,000E Mild, waxy, odorless, oily
      50 28.398 1,411 3,8-Dimethyl-decane 44.83 ± 0.80 a 2.19 ± 0.11 b n.f. Hydrocarbon
      51 29.075 1,433 2,6,11-Trimethyl-dodecane 65.22 ± 8.29 a 7.33 ± 0.41 b n.f. Odorless, oily
      52 29.898 1,460 2,6,10-Trimethyl-tridecane 191.03 ± 22.37 a 30.74 ± 1.70 b n.f. Odorless, oily
      53 30.719 1,487 5-Methyl-5-propylnonane 143.54 ± 21.80 a 37.71 ± 0.56 b n.f. Odorless
      54 31.749 1,522 2,6,10-Trimethyl-tetradecane 26.96 ± 2.17 a 5.95 ± 0.29 b n.f. Odorless
      55 33.947 1,598 Hexadecane 438.21 ± 32.59 a 11.97 ± 0.91 b 13,000,000E Odorless, oily
      56 33.971 1,599 3-Methyl-5-propylnonane 50.05 ± 3.83 a 1.19 ± 0.14 b n.f. Odorless, oily, waxy
      57 35.296 1,647 2,6,10,15-Tetramethyl-heptadecane 117.06 ± 9.36 a 16.75 ± 0.63 b n.f. Oily, waxy, petroleum
      58 36.697 1,698 8-Methyl-heptadecane 139.98 ± 5.29 a 17.17 ± 0.25 b n.f. Mild, hydrocarbon
      59 36.828 1,703 Phytane 47.43 ± 1.29 a 4.03 ± 0.10 b n.f. Odorless, oily
      60 37.776 1,740 3,8-Dimethyl-undecane 25.78 ± 1.40 a 3.67 ± 0.31 b n.f. Mild, fatty, hydrocarbon
      61 39.330 1,799 Octadecane 70.36 ± 0.45 a 1.91 ± 0.19 b 20E Mild, waxy, petroleum
      62 48.494 2,100 Heneicosane 393.56 ± 19.59 a 30.00 ± 1.74 b n.f. Waxy, oily, greasy
      Ketone
      63 5.896 782 3-Hexanone 74.30 ± 0.79 a 0 b 1,000C Herbaceous, fruity
      64 6.224 791 2-Hexanone 9.51 ± 0.19 a 0.91 ± 0.05 b 24F Mild, fruity, solvent
      65 9.614 885 3-Heptanone 66.35 ± 1.62 a 6.82 ± 0.39 b 1F Fruity, banana, spicy, solvent
      66 12.202 953 6-Methyl-2-heptanone 188.52 ± 5.75 a 24.91 ± 0.90 b 8.1F Fruity, banana, spicy, solvent
      67 13.521 987 2-Octanone 786.02 ± 85.85 a 0 b 350F Fruity, banana, spicy, buttery
      68 16.043 1053 2-Tetradecanone 24.05 ± 0.84 a 0.65 ± 0.07 b 10F Mild, fatty, fruity
      69 16.212 1,058 2-Dodecanone 74.54 ± 4.57 a 1.34 ± 0.15 b 42F Fatty, waxy
      70 16.467 1,064 Acetophenone 854.90 ± 65.93 a 29.31 ± 0.90 b 170D Sweet, almond, fruity, floral
      71 17.414 1,089 2-Nonanone 259.56 ± 51.80 a 24.21 ± 1.03 b 5F Herbaceous, spicy
      72 27.717 1,389 Z-Jasmone 221.25 ± 5.09 a 11.07 ± 0.30 b 7A Sweet, floral, herbaceous, fruity
      73 29.430 1,445 6,10-Dimethyl-5,9-undecadien-2-one 111.62 ± 1.68 a 20.60 ± 1.49 b 3,000D Fruity, sweet
      74 31.486 1,513 2-(2-Propenyl)-1,3-cyclohexanedione 107.72 ± 0.60 a 22.54 ± 1.40 b n.f. Mild, herbal, spicy
      75 40.304 1,838 Phytone 48.91 ± 1.10 a 7.71 ± 0.22 b n.f. Woody, herbaceous, earthy
      Alcohol
      76 8.878 865 6-Methyl-1-heptanol 75.94 ± 3.40 a 9.50 ± 1.00 b n.f. Faint scent, fatty,herbal
      77 9.018 869 1-Hexanol 140.47 ± 9.33 a 3.95 ± 0.54 b 500A Fruity, alcoholic, sweet, green
      78 10.243 903 4-Methyl-2-hexanol 17.39 ± 0.96 a 0.84 ± 0.06 b n.f. Faint scent, alcoholic, mild, floral
      79 14.172 1,004 2,6-Dimethyl-1,7-octadiene-3,6-diol 432.70 ± 8.06 a 0 b 10F Faint scent, herbal, citrus, lemon
      80 14.538 1,014 2-Butyl-1-octanol 38.72 ± 3.21 a 4.42 ± 0.05 b n.f. Mild, fatty, hydrocarbon
      81 14.782 1,020 4-Pentenol 10.83 ± 0.63 a 1.81 ± 0.17 b 1F Faint scent, herbal, fruity
      82 16.674 1,035 1-Decanol 542.52 ± 25.03 a 40.97 ± 1.24 b 23C Mild fatty, waxy, floral, orange
      83 17.274 1,086 Z-Linalool oxide (furanoid) 830.56 ± 104.82 a 77.69 ± 2.41 b 320C Earthy, floral, sweet, herbal
      84 17.699 1,097 Linalool 8,805.09 ± 298.70 a 1,424.74 ± 32.19 b 0.6A Sweet floral, citrus
      85 19.675 1,151 Z-3-Nonenol 25.93 ± 1.18 a 0.85 ± 0.03 b n.f. Faint scent, herbal, green
      86 20.369 1,171 1-Nonanol 379.02 ± 23.01 a 26.90 ± 0.51 b 5.3C Faint scent, floral,dusty
      87 20.456 1,173 E-Linalool oxide (pyranoid) 104.72 ± 6.25 a 25.07 ± 1.61 b 3,000G Sweet, floral, woody, herbaceous
      88 21.910 1,214 7-Methyl-3-methylene-6-octenol 59.19 ± 5.26 a 0 b n.f. Faint scent, herbal,green
      89 22.344 1,227 3Z-3,7-Dimethyl-3,6-octadienol 114.09 ± 0.66 a 1.78 ± 0.41 b n.f. Sweet, floral, rose, citrusy
      90 22.879 1,242 2-(4-Methylidenecyclohexyl) prop-2-enol 34.60 ± 1.38 a 4.53 ± 0.31 b n.f. Mild, herbal, floral
      91 23.084 1,248 Nerol 18,033.70 ± 2247.35 a 296.16 ± 38.27 b 290A Floral, fruity, lemon, faint scent
      92 28.280 1,407 E-2-Decenol 42.70 ± 1.80 a 2.40 ± 0.14 b n.f. Faint scent, fatty, waxy, herbal
      93 29.294 1,440 Dihydro-β-ionol 30.35 ± 1.97 a 3.36 ± 0.22 b n.f. Floral, woody
      94 32.648 1,453 2-Isopropyl-5-methyl-1-hexanol 13.52 ± 1.23 a 2.16 ± 0.35 b 50F Faint scent, floral,herbal
      95 42.868 1,491 Phytol 41.35 ± 0.71 a 3.33 ± 0.55 b 640E Herbaceous, woody, faint scent
      Alkene
      96 5.610 774 1,3,5-Cycloheptatriene 11.15 ± 0.58 a 1.50 ± 0.11 b n.f. Mild, solvent
      97 8.894 865 2,6-Dimethyl-2-heptene 40.50 ± 0.82 a 14.93 ± 0.37 b n.f. Mild, hydrocarbon
      98 15.760 1,046 3-Carene 45.07 ± 3.96 a 0 b 770F Faint scent, pine, citrusy, sweet
      99 18.843 1,128 E,Z-2,6-Dimethylocta-2,4,6-triene 0 b 10.29 ± 0.06 a 0.03F Floral, herbal, balsamic
      100 18.848 1,129 2,6-Dimethyl-2,4,6-octatriene 104.78 ± 12.48 a 15.90 ± 0.29 b n.f. Strong, herbal, green, faint scent
      101 29.622 1,451 E-β-Farnesene 118.87 ± 14.63 a 15.47 ± 1.12 b 87B Sweet, floral, fruity, woody
      102 31.511 1,514 Copaene 56.27 ± 5.40 a 19.76 ± 0.44 b 6C Spicy, honey, faint scent, piney, woody, citrusy
      103 31.604 1,517 (+)-Delta-cadinene 74.74 ± 2.43 a 16.49 ± 1.44 b 1.5C Herbal, woody
      104 31.689 1,520 E-Calamenene 37.46 ± 0.36 a 6.81 ± 0.28 b n.f. Spicy, woody
      Aromatics
      105 8.481 854 Ethylbenzene 27.87 ± 2.53 a 0 b 170C Aromati
      106 9.718 888 Styrene 237.98 ± 22.96 a 9.99 ± 0.70 b 730D Balsamic, gasoline, sweet,
      107 13.245 980 α-Methylstyrene 93.35 ± 1.74 a 17.97 ± 6.59 b n.f. Aromatic, sweet
      108 14.981 989 p-Cymene 54.96 ± 0.79 a 3.96 ± 1.16 b 11.4A Woody, citrus, aromatic, sweet
      109 24.602 1,293 1-Methylnaphthalene 111.86 ± 3.83 a 17.52 ± 1.09 b 14D Aromatic, coal-tar, oily, solvent
      Heterocyclic compound
      110 28.991 1,430 Coumarin 95.51 ± 3.87 a 7.25 ± 1.09 b 11A Sweet, vanilla, hay ,almond
      111 31.174 1,502 2,4-Di-tert-butylphenol 652.49 ± 20.81 a 59.30 ± 2.73 b 500C Phenol, sweet, rubbery, plastic
      112 40.098 1,830 Caffeine 352.30 ± 26.56 a 110.84 ± 5.90 b n.f. Mild bitter, herbal
      'n.f.', odor thresholds of related compounds not found in the literature. All the odor thresholds and odor description were obtained from: A[26]; B[56]; C (www.thegoodscentscompany.com/search2.html); D[16]; E[57]; F[58]; G[59]. 'a, b', significant differences in the relative content of differential volatile compounds between GT and OT. (p < 0.05, GT: n = 15, OT: n = 16).

      Table 1. 

      Differential volatile compounds between GT and OT.