Table 2.
Volatile compounds quantified in two Syrah wine samples using Headspace GC-Flame Ionization Detector (HS-GC-FID) and Stir Bar Sorptive Extraction-GC-Mass Spectrometry (SBSE-GC-MS).
| No. | Compounds | Odor * | Concentration ** (μg/L, mean ± SD) | OAV *** | ||
|---|---|---|---|---|---|---|
| Threshold | NS | YS | NS | YS | ||
| Ethyl esters of straight-chain fatty acid | ||||||
| 1 | ethyl acetate | 12,300 | 52,086 ± 3892 a | 81,445 ± 5481 b | 4.23 | 6.62 |
| 2 | ethyl propionate | 2100 | 204 ± 25 | 184 ± 47 | <0.1 | <0.1 |
| 3 | ethyl butanoate | 20 | 167 ± 12 a | 120 ± 21 b | 8.36 | 6.02 |
| 4 | ethyl hexanoate | 14 | 533 ± 32 a | 151 ± 13 b | 38.1 | 10.8 |
| 5 | ethyl octanoate | 5 | 275 ± 22 a | 58 ± 8 b | 54.9 | 11.7 |
| 6 | ethyl decanoate | 200 | 99.1 ± 5.3 a | 16.3 ± 2 b | 0.1–0.5 | <0.1 |
| Ethyl esters of branched-chain fatty acid | ||||||
| 7 | ethyl isobutyrate | 15 | 264 ± 24 a | 164 ± 29 b | 17.6 | 10.9 |
| 8 | ethyl 2-methylbutanoate | 18 | 79.6 ± 3.4 a | 48.2 ± 5.4 b | 4.42 | 2.68 |
| 9 | ethyl isovalerate | 3 | 131 ± 5 a | 82 ± 9 b | 43.8 | 27.3 |
| Higher alcohol acetates | ||||||
| 10 | isobutyl acetate | 1800 | 78.1 ± 6.3 a | 61.0 ± 10.1 b | <0.1 | <0.1 |
| 11 | butyl acetate | 1600 | 23.4 ± 1.1 a | 14.6 ± 1.6 b | <0.1 | <0.1 |
| 12 | isoamyl acetate | 30 | 408 ± 26 a | 244 ± 13 b | 13.6 | 8.1 |
| 13 | hexyl acetate | 670 | 3.31 ± 0.37 a | 0.76 ± 0.14 b | <0.1 | <0.1 |
| 14 | octyl acetate | 50,000 | 3.85 ± 0.08 a | 2.5 ± 0.12 b | <0.1 | <0.1 |
| Aromatic esters and others | ||||||
| 15 | phenethyl acetate | 73 | 33.3 ± 0.9 a | 20.3 ± 1.2 b | 0.1–0.5 | 0.1–0.5 |
| 16 | ethyl phenylacetate | 250 | 5.51 ± 0.26 | 5.92 ± 0.26 | <0.1 | <0.1 |
| 17 | ethyl dihydrocinnamate | 1.6 | 1.68 ± 0.58 a | 0.41 ± 0.26 b | 1.05 | 0.1–0.5 |
| 18 | ethyl cinnamate | 1.1 | 0.51 ± 0.13 | 0.37 ± 0.23 | 0.1–0.5 | 0.1–0.5 |
| 19 | methyl anthranilate | 3 | 0.7 ± 0.12 a | 1.52 ± 0.24 b | 0.1–0.5 | 0.5–1 |
| 20 | ethyl anthranilate | 16 | 0.39 ± 0.26 a | 1.31 ± 0.26 b | <0.1 | <0.1 |
| 21 | methyl vanillate | 3000 | 5.68 ± 2.62 a | 13.5 ± 0.14 b | <0.1 | <0.1 |
| 22 | ethyl vanillate | 990 | 499± 245 | 898 ± 307 | 0.5–1 | 0.5–1 |
| 23 | diethyl succinate | 120,000 | 11311 ± 1078 | 9736 ± 958 | <0.1 | <0.1 |
| Alcohols | ||||||
| 24 | 1-propanol | 50,000 | 31,180 ± 4642 | 38,252 ± 2941 | 0.5–1 | 0.5–1 |
| 25 | isobutyl alcohol | 40,000 | 52,872 ± 5530 | 47,188 ± 4978 | 1.32 | 1.18 |
| 26 | isoamyl alcohol | 30,000 | 123,435 ± 8642 | 105,594 ± 7374 | 4.11 | 3.52 |
| 27 | 1-hexanol | 8000 | 1046 ± 35 a | 1279 ± 63 b | 0.1–0.5 | 0.1–0.5 |
| 28 | cis-3-hexen-1-ol | 1000 | 10.1 ± 4.9 | 12.7 ± 3.4 | <0.1 | <0.1 |
| 29 | trans-2-hexen-1-ol | 1000 | 6.98 ± 2.42 | 8.77 ± 3.16 | <0.1 | <0.1 |
| 30 | 1-octen-3-ol | 20 | 14.3 ± 0.4 a | 17.8 ± 0.9 b | 0.5–1 | 0.5–1 |
| 31 | benzyl alcohol | 200,000 | 218 ± 52 a | 595 ± 80 b | <0.1 | <0.1 |
| 32 | 2-phenethanol | 14,000 | 13793 ± 1724 a | 9628 ± 801 b | 0.5–1 | 0.5–1 |
| Fatty acids | ||||||
| 33 | butanoic acid | 173 | 550 ± 63 | 484 ± 70 | 3.18 | 2.80 |
| 34 | hexanoic acid | 420 | 1489 ± 165 a | 1076 ± 140 b | 3.55 | 2.56 |
| 35 | octanoic acid | 500 | 650 ± 51 | 579 ± 68 | 1.30 | 1.16 |
| 36 | decanoic acid | 1000 | 122 ± 14 a | 72 ± 16 b | 0.1–0.5 | <0.1 |
| 37 | 2-methylpropanoic acid | 2300 | 730 ± 102 a | 544 ± 96 b | 0.1–0.5 | 0.1–0.5 |
| 38 | 2- and 3-methylbutyric acid | 33 | 564 ± 134 a | 390 ± 43 b | 17.1 | 11.8 |
| Shikimic acid derivatives (volatile phenols) | ||||||
| 39 | guaiacol | 23 | 28.8 ± 3.4 a | 36.3 ± 3.1 b | 1.25 | 1.58 |
| 40 | 4-methylguaiacol | 65 | 1.98 ± 0.97 a | 9.56 ± 0.15 b | <0.1 | 0.1–0.5 |
| 41 | 4-ethylguaiacol | 33 | 1.23 ± 0.43 a | 14.75 ± 0.69 b | <0.1 | 0.1–0.5 |
| 42 | 4-vinylguaiacol | 1100 | 20 ± 4.5 | 17.8 ± 1.4 | <0.1 | <0.1 |
| 43 | o-cresol | 31 | 5.86 ± 2.2 | 3.19 ± 0.17 | 0.1–0.5 | 0.1–0.5 |
| 44 | p-cresol | 60 | 3.4 ± 1.64 | 4.44 ± 0.28 | <0.1 | <0.1 |
| 45 | m-cresol | 68 | 3.11 ± 1.69 | 2.36 ± 0.11 | <0.1 | <0.1 |
| 46 | eugenol | 6 | 6.71 ± 1.25 | 7.16 ± 3.19 | 1.12 | 1.19 |
| 47 | isoeugenol | 6 | 0.44 ± 0.23 | 0.61 ± 0.25 | <0.1 | 0.1–0.5 |
| 48 | 4-ethylphenol | 440 | 1.76 ± 0.61 a | 101 ± 11 b | <0.1 | 0.1–0.5 |
| 49 | 3-ethylphenol | 250 | 1.86 ± 0.12 a | 87 ± 12 b | <0.1 | 0.1–0.5 |
| 50 | 4-vinylphenol | 180 | 56.9 ± 13.3 a | 81.2 ± 6.6 b | 0.1–0.5 | 0.1–0.5 |
| Terpenoids | ||||||
| 51 | linalool | 15 | 11.6 ± 0.3 a | 1.81 ± 0.05 b | 0.1–0.5 | 0.1–0.5 |
| 52 | α-terpineol | 250 | 14.6 ± 0.1 a | 12 ± 0.7 b | <0.1 | <0.1 |
| 53 | citronellol | 100 | 1.76 ± 0.03 a | 0.66 ± 0.05 b | <0.1 | <0.1 |
| 54 | geraniol | 30 | 6.13 ± 0.72 a | 1.73 ± 0.36 b | 0.1–0.5 | <0.1 |
| 55 | nerol | 300 | 8.98 ± 0.65 | 10.4 ± 1.4 | <0.1 | <0.1 |
| 56 | rose oxide | 0.2 | 0.03 ± 0.01 | 0.04 ± 0.03 | 0.1–0.5 | 0.1–0.5 |
| 57 | linalool oxide | 3000 | 1.72 ± 0.36 a | 5.69 ± 0.49 b | <0.1 | <0.1 |
| C13-norisoprenoids | ||||||
| 58 | β-damascenone | 0.05 | 2.81 ± 0.1 a | 0.22 ± 0.03 b | 56.1 | 24.4 |
| 59 | β-ionone | 5 | 0.12 ± 0.02 | 0.09 ± 0.08 | <0.1 | <0.1 |
| Ketone and lactones | ||||||
| 60 | γ-octalactone | 400 | 6.24 ± 1.56 | 5.15 ± 0.6 | <0.1 | <0.1 |
| 61 | γ-nonalactone | 30 | 8.33 ± 0.86 | 11 ± 1.98 | 0.1–0.5 | 0.1–0.5 |
| 62 | γ-decalactone | 88 | 0.6 ± 0.04 a | 1.34 ± 0.29 b | <0.1 | <0.1 |
| 63 | γ-undecalactone | 150 | 5.61 ± 0.72 a | 3.71 ± 0.83 b | <0.1 | <0.1 |
| 64 | cis-whiskylactone | 74 | 12.7 ± 2.5 a | 33.9 ± 1.3 b | 0.1–0.5 | 0.1–0.5 |
| 65 | trans-whiskylactone | 32 | 31.5 ± 4.2 | 58.3 ± 2.1 | 0.5–1 | 1.82 |
| 66 | 2-aminoacetophenone | 1.4 | 1.01 ± 0.15 | 1.18 ± 0.11 | 0.5–1 | 0.5–1 |
| Aldehydes | ||||||
| 67 | acetaldehyde | 500 | 22,343 ± 1397 a | 31,905 ± 2231 b | 44.7 | 63.8 |
| 68 | cinnamaldehyde | 1180 | 0.18 ± 0.03 a | 0.46 ± 0.16 b | <0.1 | <0.1 |
| 69 | vanillin | 200 | 88.8 ± 6.7 a | 110 ± 8 b | 0.1–0.5 | 0.5–1 |
| Methoxypyrazines | ||||||
| 70 | 3-isopropyl-2-methoxypyrazine | 0.015 | 0.001 ± 0.0003 | N.D. | <0.1 | <0.1 |
| 71 | 3-sec-butyl-2-methoxypyrazine | 0.015 | N.D. | 0.0012 ± 0.0004 | <0.1 | <0.1 |
| 72 | 3-isobutyl-2-methoxypyrazine | 0.002 | 0.0017 ± 0.001 | 0.0012 ± 0.0004 | 0.5–1 | 0.5–1 |
* Odor threshold of the volatiles were presented in μg/L. They were measured in model wine, water/ethanol (90 + 10, w/w) unless indicated, and referenced from the literature: [3,34,35,37,38,39,40,41,42,43,44,45]; ** Different letters within rows indicates statistical differences by the Duncan test (p < 0.05); *** OAV means odor activity value, calculated as the ratio between the concentration of the individual compound in wine and the threshold concentration of this substance.