Table 1.

Concentration of volatiles in tea leaves of typical oolong tea.

NO.	Compounds	Odor descriptiona	RI	Concentration (μg/g dry weight of tea leaves) b
				HMT	TGYT	DDT	WRT
Alcohols
1	4-Pyridylcarbinol	Hazelnut, coffee, nutty	1242	n.d.	n.d.	0.312 ± 0.389	n.d.
2	1-Pentanol	Pungent, solvent-like	1251	0.027 ± 0.027	0.005 ± 0.014	0.011 ± 0.057	0.008 ± 0.032
3	4-Pyridinemethanol	Hazelnut, coffee, nutty	1278	n.d.	n.d.	0.263 ± 0.461	n.d.
4	1-Hexanol	Pungent, sweet, green	1346	0.001 ± 0.005	n.d.	n.d.	0.048 ± 0.069
5	3-Hexen-1-ol	Green, leafy	1373	0.025 ± 0.049	n.d.	n.d.	0.005 ± 0.028
6	(E)-Linalool oxide	–	1425	0.278 ± 0.122	0.213 ± 0.106	0.887 ± 0.713	1.933 ± 0.823
7	1-Octen-3-ol	Earthy, green	1442	0.030 ± 0.038	0.083 ± 0.031	0.023 ± 0.058	0.188 ± 0.166
8	1-Decanol	Fatty, waxy	1444	0.002 ± 0.010	0.015 ± 0.032	0.001 ± 0.007	0.026 ± 0.094
9	(Z)-Linalool oxide	–	1454	0.221 ± 0.123	0.114 ± 0.073	0.512 ± 0.228	0.793 ± 0.337
10	Linalool	Citrus, floral	1539	1.154 ± 0.625	0.764 ± 0.255	0.486 ± 0.175	0.777 ± 0.543
11	1-Octanol	Waxy, green, orange	1543	0.016 ± 0.038	0.012 ± 0.038	n.d.	0.153 ± 0.121
12	Hotrienol	Fresh, floral, woody	1597	0.981 ± 0.599	0.666 ± 0.267	2.692 ± 1.442	2.153 ± 2.709
13	α-Terpineol	Pine, terpenic, lilac	1674	0.000 ± 0.001	n.d.	n.d.	0.026 ± 0.065
14	Nerol	Sweet, natural, neroli	1780	n.d.	n.d.	n.d.	0.005 ± 0.020
15	Geraniol	Sweet, floral, fruity	1830	0.645 ± 0.416	0.071 ± 0.121	0.235 ± 0.157	0.423 ± 0.456
16	Benzyl alcohol	Floral, rose, phenolic	1850	0.076 ± 0.049	0.070 ± 0.050	0.100 ± 0.049	0.319 ± 0.143
17	Phenylethyl alcohol	Floral, rose	1883	0.371 ± 0.395	0.585 ± 0.432	0.152 ± 0.119	0.728 ± 0.453
18	(E)-Nerolidol	Floral, green, citrus	2020	0.792 ± 0.624	3.471 ± 1.031	0.208 ± 0.201	0.785 ± 0.579
	Total alcohols			4.618 ± 1.616	6.068 ± 1.458	5.882 ± 2.049	8.371 ± 4.531
	Proportion			46.7% ± 14.1%	34.6% ± 4.1%	25.3% ± 10.0%	28.6% ± 11.8%
Aldehydes
19	Hexanal	Fresh, green, fatty	–	0.076 ± 0.135	0.342 ± 0.169	0.027 ± 0.063	0.331 ± 0.314
20	2-Hexenal	Sweet, almond, bitter	1201	n.d.	0.000 ± 0.001	n.d.	0.035 ± 0.059
21	1-Methyl pyrrole-2-carboxaldehyde	–	1276	n.d.	n.d.	0.349 ± 0.425	n.d.
22	(E,E)-2,4-Heptadienal	Fatty, green, oily	1447	0.101 ± 0.113	0.529 ± 0.213	0.642 ± 0.787	0.537 ± 0.730
23	(Z,E)-2,4-Heptadienal	Fatty, green, oily	1474	0.119 ± 0.106	0.543 ± 0.235	0.454 ± 0.489	1.092 ± 0.684
24	Decanal	Sweet, aldehydic, waxy	1479	0.016 ± 0.044	0.023 ± 0.051	0.003 ± 0.011	0.013 ± 0.045
25	Benzaldehyde	Sharp, sweet, bitter	1496	0.155 ± 0.137	0.404 ± 0.202	0.399 ± 0.184	1.408 ± 0.556
26	(E,Z)-2,6-Nonadienal	Green, fatty, dry	1562	n.d.	n.d.	n.d.	0.011 ± 0.025
27	β-Cyclocitral	Tropical, saffron, herbal	1584	0.057 ± 0.058	0.146 ± 0.098	0.072 ± 0.085	0.347 ± 0.130
28	Benzeneacetaldehyde	Green, sweet, floral	1612	0.535 ± 0.673	1.881 ± 0.929	n.d.	0.102 ± 0.355
29	2-Hydroxy-5-methyl benzaldehyde	–	1753	n.d.	n.d.	n.d.	0.002 ± 0.012
30	2,4-Dimethylbenzaldehyde	Naphthyl, cherry, almond	1779	0.002 ± 0.005	n.d.	n.d.	0.001 ± 0.004
31	α-Ethylidene-benzeneacetaldehyde	–	1896	n.d.	0.001 ± 0.004	0.002 ± 0.009	0.023 ± 0.029
32	1H-Pyrrole-2-carboxaldehyde	Musty, beefy, coffee	1989	n.d.	n.d.	n.d.	0.040 ± 0.049
	Total Aldehydes			1.061 ± 0.934	3.870 ± 1.555	1.948 ± 1.171	3.942 ± 1.691
	Proportion			8.8% ± 5.2%	21.6% ± 5.0%	8.4% ± 5.1%	13.3% ± 4.0%
Acids
33	Hexanoic acid	Sour, fatty, sweaty, cheesy	1588	n.d.	0.018 ± 0.068	0.018 ± 0.041	0.881 ± 0.497
34	Heptanoic acid	Sour, fatty, sweaty, cheesy	1929	n.d.	n.d.	n.d.	0.095 ± 0.083
35	(E)-3-Hexenoic acid	Fruity, honey, acidic	1935	n.d.	n.d.	n.d.	0.033 ± 0.087
36	2-Hexenoic acid	–	1944	n.d.	n.d.	n.d.	0.035 ± 0.090
37	Octanoic acid	Fatty, waxy, rancid	2034	n.d.	n.d.	n.d.	0.074 ± 0.060
	Total Acids			n.d.	0.018 ± 0.068	0.018 ± 0.041	1.117 ± 0.707
	Proportion			n.d.	0.1% ± 0.3%	0.1% ± 0.2%	3.8% ± 2.1%
Hydrocarbons
38	p-Xylene	–	1120	n.d.	n.d.	0.266 ± 0.248	0.479 ± 0.632
39	Limonene	Citrus, orange, fresh, sweet	1158	0.001 ± 0.007	n.d.	n.d.	0.034 ± 0.098
40	1-Methyl cycloheptene	–	1183	n.d.	n.d.	0.002 ± 0.009	0.002 ± 0.011
41	(E)-β-Ocimene	Sweet, herbal	1231	0.028 ± 0.050	n.d.	0.015 ± 0.046	n.d.
42	Vinylcyclohexane	–	1449	0.012 ± 0.035	n.d.	n.d.	n.d.
43	Azulene	–	1698	n.d.	n.d.	0.008 ± 0.041	n.d.
44	α-Farnesene	Floral, woody	1732	0.301 ± 0.485	0.601 ± 0.461	0.050 ± 0.176	0.023 ± 0.065
	Total hydrocarbons			0.342 ± 0.527	0.601 ± 0.461	0.341 ± 0.255	0.537 ± 0.637
	Proportion			2.3% ± 2.9%	3.4% ± 2.7%	1.4% ± 1.2%	1.7% ± 1.4%
Ketones
45	2-Octanone	Earthy, weedy, natural	1269	0.000 ± 0.002	n.d.	n.d.	0.045 ± 0.049
46	2,2,6-Trimethyl cyclohexan-1-one	Pungent, thujonic, labdanum	1286	0.006 ± 0.015	0.001 ± 0.005	0.003 ± 0.008	0.181 ± 0.096
47	2,3-Octanedione	Dill, asparagus, cilantro	1309	0.005 ± 0.018	0.003 ± 0.017	n.d.	n.d.
48	2-Methyl-3-octanone	–	1318	0.007 ± 0.023	n.d.	n.d.	n.d.
49	6-Methyl-5-hepten-2-one	Citrus, green, musty	1326	0.158 ± 0.135	0.516 ± 0.513	0.094 ± 0.184	0.749 ± 0.702
50	3-Octen-2-one	Earthy, spicy, herbal	1387	0.002 ± 0.011	n.d.	n.d.	0.007 ± 0.024
51	3,4-Dihydroxyacetophenone	–	1486	n.d.	n.d.	n.d.	0.078 ± 0.150
52	3,5-Octadien-2-one	Fruity, fatty, mushroom	1498	0.079 ± 0.067	0.225 ± 0.113	0.289 ± 0.283	0.513 ± 0.364
53	(E,E)-3,5-Octadien-2-one	Fruity, fatty, mushroom	1547	0.037 ± 0.158	0.017 ± 0.016	0.040 ± 0.040	0.160 ± 0.099
54	3,5,5-Trimethyl-2-cyclopenten-1-one	–	1571	0.003 ± 0.015	n.d.	0.002 ± 0.012	n.d.
55	Acetophenone	Sweet, pungent, hawthorn	1620	0.003 ± 0.013	0.000 ± 0.002	0.094 ± 0.090	0.220 ± 0.201
56	2,6,6-Trimethyl-2-cyclohexene-1,4-dione	Musty, woody, sweet	1662	n.d.	n.d.	n.d.	0.005 ± 0.023
57	1-Phenyl-1-propanone	Hawthorn, lilac, floral	1690	n.d.	n.d.	0.010 ± 0.026	0.184 ± 0.204
58	α-Ionone	Sweet, woody, floral	1818	0.004 ± 0.008	0.023 ± 0.023	0.012 ± 0.012	0.064 ± 0.036
59	(E)-β-Ionone	Dry, powdery, floral	1904	0.038 ± 0.048	0.095 ± 0.151	0.063 ± 0.096	0.389 ± 0.170
60	(Z)-Jasmone	Woody, herbal, floral	1908	0.167 ± 0.136	0.302 ± 0.139	0.164 ± 0.138	0.033 ± 0.101
61	4-(2,2,6-Trimethyl-7-oxabicyclo hept-1-yl)-3-buten-2-one	Fruity, sweet, berry	1959	0.006 ± 0.014	0.032 ± 0.033	0.002 ± 0.006	0.061 ± 0.046
62	5-Methyl-2-(1-methylethyl)-2-cyclohexen-1-one	–	2137	0.001 ± 0.004	0.002 ± 0.011	n.d.	0.004 ± 0.016
	Total ketones			0.514 ± 0.287	1.217 ± 0.533	0.771 ± 0.459	2.692 ± 1.340
	Proportion			5.1% ± 2.7%	7.0% ± 2.7%	3.4% ± 2.2%	9.1% ± 3.1%
Heterocyclic compounds
63	N-Ethyl pyrrole		1169	0.018 ± 0.070	n.d.	2.485 ± 1.228	0.547 ± 0.668
64	3-(Hydroxymethyl) pyridine	Bitter, green	1245	n.d.	n.d.	0.371 ± 0.381	0.002 ± 0.017
65	4,6-Dimethyl pyrimidine	–	1302	n.d.	n.d.	0.101 ± 0.089	0.033 ± 0.081
66	2,5-Dimethyl pyrazine	Cocoa, roasted, nutty	1302	n.d.	n.d.	0.046 ± 0.097	n.d.
67	2,6-Dimethyl pyrazine	Burnt, almond, roasted	1304	0.002 ± 0.011	n.d.	0.117 ± 0.131	0.114 ± 0.141
68	2-Ethyl pyrazine	Peanut, butter, musty	1315	n.d.	n.d.	0.058 ± 0.079	0.057 ± 0.098
69	4-Methyl-1,3-benzenediamine	–	1365	n.d.	n.d.	0.006 ± 0.019	n.d.
70	2-Ethyl-3-methyl pyrazine	Nutty, peanut, musty	1366	n.d.	n.d.	0.045 ± 0.051	0.014 ± 0.057
71	2-Ethyl-5-methyl pyrazine	Coffee, beany, nutty	1371	0.005 ± 0.024	n.d.	0.288 ± 0.130	0.249 ± 0.175
72	4,5-Dihydro-5,5-dimethyl-4-isopropylidene-1H pyrazole	–	1375	n.d.	n.d.	n.d.	0.091 ± 0.174
73	2,6-Dimethyl-3-pyridinamine	–	1384	n.d.	n.d.	0.041 ± 0.056	0.062 ± 0.104
74	Furfural	Sweet, woody, almond	1448	n.d.	n.d.	0.277 ± 0.335	0.771 ± 0.917
75	3-Ethyl-2,5-dimethyl pyrazine	Potato, cocoa, roasted, nutty	1428	n.d.	n.d.	0.078 ± 0.278	n.d.
76	2,5-Diethyl pyrazine	Nutty, hazelnut	1437	n.d.	n.d.	0.019 ± 0.032	0.000 ± 0.002
77	2-Ethyl-3,5-dimethyl pyrazine	Burnt, almond, caramel, roasted	1440	n.d.	n.d.	0.056 ± 0.087	n.d.
78	3,5-Diethyl-2-methyl pyrazine	–	1473	0.002 ± 0.011	n.d.	0.077 ± 0.127	n.d.
79	2-Acetylfuran	Sweet, balsamic, almond	1484	0.003 ± 0.015	n.d.	0.083 ± 0.051	0.105 ± 0.085
80	2,5-Dimethyl-3-(2-methyl propyl) pyrazine	–	1503	n.d.	n.d.	0.002 ± 0.009	0.007 ± 0.018
81	5-Methyl furfural	Spicy, caramellic, maple	1552	0.004 ± 0.029	n.d.	0.298 ± 0.144	0.562 ± 0.451
82	Benzonitrile	–	1574	n.d.	n.d.	0.013 ± 0.047	n.d.
83	1-Ethyl-1H-pyrrole-2-carboxaldehyde	Burnt, roasted, smoky	1581	0.102 ± 0.198	0.015 ± 0.029	5.096 ± 2.153	2.887 ± 1.601
84	1-Methyl-1H-pyrrole-2-carboxaldehyde	–	1591	n.d.	n.d.	0.005 ± 0.018	0.042 ± 0.057
85	2-Methyl-4-methoxyaniline	–	1613	0.025 ± 0.110	n.d.	1.930 ± 0.913	1.147 ± 0.616
86	Phthalan	–	1623	0.019 ± 0.050	0.110 ± 0.154	n.d.	0.029 ± 0.207
87	1,2-Dihydro-1,5,8-trimethyl naphthalene	–	1707	n.d.	n.d.	0.045 ± 0.019	0.082 ± 0.084
88	Tetrahydro-2,2,6-trimethyl-6-vinyl-2H pyran-3-ol	Floral, honey	1716	0.072 ± 0.104	0.096 ± 0.099	0.006 ± 0.022	0.152 ± 0.208
89	4-Amino-2,3-xylenol	–	1721	0.010 ± 0.069	n.d.	0.657 ± 0.713	0.207 ± 0.351
90	6-Ethenyl tetrahydro-2,2,6-trimethyl-2H pyran-3-ol	Floral, honey	1747	0.006 ± 0.023	0.000 ± 0.003	n.d.	0.035 ± 0.062
91	2-Methyl-benzenemethanamine	–	1789	0.002 ± 0.009	n.d.	0.009 ± 0.027	0.019 ± 0.043
92	2-Cyclopropyl-benzenamine	–	1795	n.d.	n.d.	0.001 ± 0.006	0.033 ± 0.081
93	1-Furfuryl pyrrole	Plastic, green, waxy	1801	0.002 ± 0.011	n.d.	0.207 ± 0.086	0.165 ± 0.099
94	Benzyl nitrile	–	1894	0.631 ± 0.663	0.498 ± 0.273	0.667 ± 0.349	2.206 ± 1.320
95	2-Acetyl pyrrole	Musty, nut, skin, cherry	1940	0.006 ± 0.025	n.d.	0.133 ± 0.049	0.181 ± 0.075
96	4-(2,6,6-Trimethylcyclohexa-1,3-dienyl) but-3-en-2-one	–	1970	n.d.	n.d.	n.d.	0.010 ± 0.020
97	Phenol	Phenolic, plastic, rubbery	1978	n.d.	n.d.	0.001 ± 0.005	0.016 ± 0.026
98	3-Methyl phenol	–	2052	n.d.	n.d.	n.d.	0.005 ± 0.014
99	4-Methyl benzaldehyde oxime	–	2262	0.016 ± 0.046	0.048 ± 0.045	n.d.	n.d.
100	3,5-bis (1,1-Dimethylethyl) phenol	–	2283	0.001 ± 0.004	0.004 ± 0.008	n.d.	0.007 ± 0.012
101	Eugenol	Sweet, spicy, clove, woody	2309	0.015 ± 0.022	0.012 ± 0.014	0.004 ± 0.010	0.014 ± 0.030
102	2,3-Dihydro benzofuran	–	2352	n.d.	n.d.	0.027 ± 0.017	0.016 ± 0.019
103	Indole	Animal, floral, naphthyl, fecal	2396	2.679 ± 1.922	4.132 ± 1.260	0.892 ± 0.545	0.543 ± 0.386
	Total heterocyclic compounds			3.620 ± 2.598	4.916 ± 1.480	14.142 ± 5.551	10.411 ± 4.177
	Proportion			30.6% ± 10.5%	27.7% ± 4.4%	55.4% ± 11.7%	35.1% ± 9.5%
Esters
104	(Z)-3-Hexenoic acid methyl ester	Fruity	1244	0.001 ± 0.004	n.d.	n.d.	0.141 ± 0.283
105	2-Methyl-propanoic acid hexyl ester	Fruity, green, apple	1394	0.002 ± 0.008	n.d.	n.d.	0.018 ± 0.044
106	Formic acid heptyl ester	Green, waxy, floral	1445	0.007 ± 0.025	0.008 ± 0.025	n.d.	0.005 ± 0.025
107	(Z)-3-Hexenyl-α-methyl butyrate	–	1457	0.001 ± 0.004	0.006 ± 0.013	0.003 ± 0.014	0.003 ± 0.016
108	2-Furanmethanol acetate	Sweet, fruity, banana	1522	0.000 ± 0.001	n.d.	0.007 ± 0.012	0.020 ± 0.027
109	2-Furoatemethyl	Fruity, mushroom, fungal	1559	n.d.	n.d.	0.072 ± 0.071	0.179 ± 0.208
110	Hexanoic acid hexyl ester	Herbal, fresh, green	1588	0.012 ± 0.027	0.001 ± 0.004	n.d.	0.076 ± 0.114
111	Caproic acid hexenyl ester	Fruity, apple, pear	1640	0.094 ± 0.072	0.066 ± 0.063	0.087 ± 0.065	0.186 ± 0.137
112	(E)-Hexanoic acid-2-hexenyl ester	Green, natural, cognac	1650	0.002 ± 0.010	n.d.	0.002 ± 0.011	0.034 ± 0.065
113	Methyl 5-hydroxynicotinate	–	1657	n.d.	n.d.	0.101 ± 0.149	0.091 ± 0.140
114	Methyl 2-oxo-1,2-dihydro-3-pyridinecarboxylate	–	1659	0.004 ± 0.015	n.d.	0.059 ± 0.117	0.027 ± 0.057
115	γ-Hexalactone	Herbal, coconut, sweet	1669	0.009 ± 0.014	0.002 ± 0.009	0.022 ± 0.023	0.007 ± 0.019
116	Acetic acid phenylmethyl ester	Sweet, floral, fruity	1703	0.000 ± 0.001	n.d.	0.012 ± 0.031	0.099 ± 0.131
117	Methyl phenylacetate	Sweet, floral, honey	1736	n.d.	n.d.	0.084 ± 0.172	0.217 ± 0.185
118	Methyl salicylate	Wintergreen, minty	1745	0.197 ± 0.147	0.204 ± 0.055	0.852 ± 0.516	0.998 ± 0.671
119	Formic acid 2-phenylethyl ester	Rose, green, hyacinth	1760	n.d.	n.d.	n.d.	0.005 ± 0.021
120	Methyl 3-amino-4-hydroxybenzoate	–	1784	n.d.	n.d.	0.006 ± 0.012	0.003 ± 0.018
121	Acetic acid 2-phenylethyl ester	Floral, rose, sweet	1787	n.d.	0.001 ± 0.007	0.004 ± 0.017	0.093 ± 0.084
122	Phenethyl butyrate	Musty, sweet, floral	1933	0.023 ± 0.042	0.026 ± 0.038	0.009 ± 0.022	0.020 ± 0.067
123	2-Phenylethyl 2-methylbutyrate	Floral, green, sweet	1941	0.005 ± 0.019	0.032 ± 0.066	n.d.	0.003 ± 0.021
124	Benzoic acid 2-phenylethyl ester	Rose, balsamic, honey, floral	2081	0.188 ± 0.249	0.303 ± 0.184	0.011 ± 0.035	0.193 ± 0.208
125	(Z)-3-Hexen-1-ol benzoate	Fresh, green, leafy	2092	0.012 ± 0.048	n.d.	0.005 ± 0.018	0.006 ± 0.028
126	Hexadecanoic acid methyl ester	Oily, waxy, fatty, orris	2193	0.000 ± 0.003	n.d.	0.001 ± 0.004	0.000 ± 0.002
127	Jasmin lactone	Creamy, waxy, jasmin	2218	0.164 ± 0.090	0.381 ± 0.120	0.175 ± 0.082	0.143 ± 0.087
128	Dihydroactinidiolide	Ripe, apricot, fruity	2294	0.006 ± 0.010	0.008 ± 0.010	0.005 ± 0.009	0.067 ± 0.050
	Total esters			0.726 ± 0.427	1.038 ± 0.384	1.518 ± 0.872	2.633 ± 1.709
	Proportion			6.5% ± 1.8%	5.8% ± 1.0%	6.0% ± 2.7%	8.3% ± 2.9%
	Total			10.881 ± 5.562	17.728 ± 4.478	24.620 ± 7.055	29.703 ± 10.036

^aThe odor descriptions were from Flavor and Extracts Manufacturers Association (FEMA) database.

^bn.d. means the compound was not detected in tea samples.