Characterization of Gardenia tea based on aroma profiles using GC-E-Nose, GC-O-MS and GC × GC-TOFMS combined with chemometrics

Figures (5) Tables (1)

Figure 1.
Information of volatile compounds in GE and GET identified by GC × GC-TOFMS. (a) Specific number of volatile categories in GE and GET. (b) Proportion of volatile categories in GE and GET. (c) Venn diagram of volatile compounds in GE and GET.
Figure 2.
Content comparisons of volatile categories in GE and GET. Different lowercase letters indicate significant difference at p < 0.05
Figure 3.
PLS-DA results of GE and GET using GC × GC-TOFMS. (a) Score plot of PLS-DA (R²Y = 0.991, Q² = 0.977). (b) Plot of 200 permutation test (R²Y = 0.838, Q² = −0.295). (c) Loading plot. (d) Fifty five key variables with VIP > 1.2. The numbers of volatile components correspond to Supplemental Table S1.
Figure 4.
Heatmap constructed with 55 key differential volatiles with VIP > 1.2 in GE and GET.
Figure 5.
Aroma wheel constructed with 24 key odorants in GET.

Compounds	RT (min)^a	Aroma descriptions^b	Aroma intensities^c	Aroma attributes^d
Propanoic acid, 2-methyl-, ethyl ester	8.58	Fruity, banana-like	3.2	Fruity
Butanoic acid, 2-methyl-, methyl ester	9.96	Fruity, apple, green pear	2.0	Fruity
Hexanoic acid, ethyl ester	19.25	Fruity, sweet	2.2	Fruity
Butanoic acid, hexyl ester	27.79	Green, fruity	3.0	Fruity
(E,E)-3,5-Octadien-2-one	34.20	Fruity, green grassy	2.0	Fruity
Benzoic acid, methyl ester	36.51	Fruity	3.0	Fruity
Benzyl alcohol	45.31	Fruity, rose-like	3.0	Fruity
Nerolidol	50.96	Fresh, floral, fruity	2.0	Fruity
Pentanal	9.08	Fermented bready	1.7	Green
Acetic acid, hexyl ester	21.11	Fruity, green	3.0	Green
(Z)-3-Hexen-1-ol, acetate	23.22	Green, sweet, fruity	2.0	Green
3-Hexen-1-ol	26.13	Green, leafy, grassy	2.2	Green
Geranylacetone	44.74	Magnolia, green	3.2	Green
Linalool	33.08	Citrus, floral, sweet	4.0	Floral
α-Ionone	44.70	Floral, violet	2.0	Floral
Phenylethyl alcohol	47.05	Rose, honey	3.2	Floral
cis-Jasmone	47.88	Jasmine-like, herbal, floral, woody	4.0	Floral
Indole	59.77	Floral, animal-like	2.0	Floral
Methyl tiglate	17.88	Ethereal	3.2	Other
1-Octanol	34.17	Matallic	2.3	Other
Methyl salicylate	42.33	Mint-like	3.2	Other
2-Methyl-butanal	9.00	Musty, chocolate, nutty	2.5	Roasted
Benzaldehyde	32.33	Bitter, almond-like	2.3	Roasted
Safranal	37.36	Woody, spicy, phenolic	2.2	Woody
^a RT: The retention time of compounds identified by GC-O-MS. ^b Aroma descriptions obtained from GC-O-MS. ^c Aroma intensity perceived by panelists. ^d Aroma attributes referred to the results of sensory evaluation.

Table 1.

A total of 24 key odorants in GET based on OAV ≥ 1 and GC-O-MS results.