Table 1.
Content of volatile compounds in original and fermented highland barley samples.
| Number | RT | Unknown RI | Literature RI | Compounds | Aroma Characteristics | CAS# | Relative Content/(%) | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| HB | SC-HB | TS-HB | SR-HB | ME-HB | CM-HB | |||||||
| Aldehydes (16) | 61.67 | 52.83 | 38.49 | 44.68 | 36.88 | 45.17 | ||||||
| 1 | 26.34 | 1208 | 1206 | Decanal | Green, Cucumber, Citrus | 112-31-2 | 4.63 ± 0.27 a | 0.51 ± 0.10 d | 0.87 ± 0.07 cd | 1.32 ± 0.06 b | 0.97 ± 0.21 bc | 1.09 ± 0.12 bc |
| 2 | 6.86 | 802 | 800 | Hexanal | Grass, Oil | 66-25-1 | 33.34 ± 3.91 a | 0.59 ± 0.22 d | 8.66 ± 1.66 bc | 10.48 ± 1.98 b | 5.03 ± 0.89 c | 5.79 ± 1.25 c |
| 3 | 20.62 | 1109 | 1102 | Nonanal | Fat, Fruity | 124-19-6 | 6.23 ± 0.67 a | 1.08 ± 0.32 c | 1.17 ± 0.10 c | 1.79 ± 0.21 c | 4.12 ± 0.67 b | 1.15 ± 0.17 c |
| 4 | 10.74 | 901 | 902 | Heptanal | Green, Fruity | 111-71-7 | 3.89 ± 0.76 a | ND | 0.21 ± 0.07 b | ND | 0.21 ± 0.11 b | 0.39 ± 0.13 b |
| 5 | 18.07 | 1059 | 1049 | Phenylacetaldehyde | Honey, Flower | 122-78-1 | 4.67 ± 1.66 c | 13.82 ± 1.46 ab | 18.30 ± 2.01 a | 10.51 ± 0.54 b | 11.99 ± 1.53 b | 3.87 ± 0.23 c |
| 6 | 13.34 | 963 | 961 | Benzaldehyde | Almond, Caramel | 100-52-7 | 8.05 ± 0.95 b | 12.72 ± 1.30 a | 6.77 ± 0.42 c | 14.63 ± 1.11 a | 9.37 ± 0.68 b | 6.46 ± 0.30 bc |
| 7 | 18.64 | 1072 | 1064 | trans-2-Octen-1-al | Grass, Oil | 2548-87-0 | 0.86 ± 0.19 c | 0.25 ± 0.04 c | 1.17 ± 0.34 c | 2.55 ± 0.67 bc | 5.20 ± 1.33 b | 9.08 ± 1.36 a |
| 8 | 28.65 | 1278 | 1274 | 2-Phenylcrotonaldehyde | Musty, Floral, tea | 4411-89-6 | ND | 1.45 ± 0.24 a | ND | ND | ND | ND |
| 9 | 11.38 | 917 | 911 | 3-methylthiopropionaldehyde | Stench | 3268-49-3 | ND | 1.96 ± 0.31 a | ND | ND | ND | ND |
| 10 | 9.28 | 863 | 846 | furan-3-carboxaldehyde | Burnt, Nutty aroma | 498-60-2 | ND | 20.46 ± 2.41 a | 1.08 ± 0.07 b | ND | ND | ND |
| 11 | 33.75 | 1582 | 1573 | Peach aldehyde | Peach | 104-67-6 | ND | ND | 0.27 ± 0.05 a | ND | ND | ND |
| 12 | 30.49 | 1366 | 1362 | gamma-nonanoic lactone | Fat, Coconut | 104-61-0 | ND | ND | ND | 2.45 ± 0.38 a | ND- | 3.04 ± 0.86 a |
| 13 | 13.26 | 962 | 956 | trans-2-Heptenal | Oil, Grass, Fruit | 18829-55-5 | ND | ND | ND | 0.94 ± 0.12 a | ND | ND |
| 14 | 14.37 | 987 | - | 2-Ethyl-2-hexenal | - | 645-62-5 | ND | ND | ND | ND | ND | 2.95 ± 0.45 a |
| 15 | 30.70 | 1378 | 1372 | (E)-2-butyloct-2-enal | Green, Oily | 13019-16-4 | ND | ND | ND | ND | ND | 5.88 ± 0.78 a |
| 16 | 12.75 | 949 | - | Cyclohexanecarboxaldehyde | - | 2043-61-0 | ND | ND | ND | ND | ND | 5.47 ± 1.20 a |
| Alcohols (8) | - | 6.34 | 12.52 | 25.55 | 46.35 | 41.16 | 22.04 | |||||
| 1 | 14.24 | 984 | 986 | 1-Octen-3-ol | Mushroom, Green | 3391-86-4 | 6.34 ± 1.65 e | 9.31 ± 1.84 de | 15.42 ± 1.41 cd | 31.15 ± 2.68 b | 27.54 ± 0.79 a | 12.17 ± 1.24 c |
| 2 | 5.73 | 752 | 768 | 1-Pentanol | Mixed alcohol oil | 71-41-0 | ND | 0.34 ± 0.07 a | ND | ND | ND | ND |
| 3 | 21.04 | 1116 | 1114 | 2-Phenylethanol | Wood incense | 60-12-8 | ND | 2.40 ± 0.28 b | 7.10 ± 0.15 b | ND | 13.62 ± 1.45 a | 4.72 ± 0.35 b |
| 4 | 29.71 | 1319 | 1313 | (1S,2S,3R,5S)-(+)-2,3-Pinanediol | Balsamic | 18680-27-8 | ND | 0.47 ± 0.11 a | ND | ND | ND | ND |
| 5 | 18.82 | 1174 | - | Cyclooctanol | - | 696-71-9 | ND | ND | 1.89 ± 0.18 a | ND | ND | ND |
| 6 | 9.59 | 871 | 867 | 1-Hexanol | Grass fragrance | 111-27-3 | ND | ND | 0.99 ± 0.17 b | 14.82 ± 1.32 a | ND | 1.11 ± 0.21 b |
| 7 | 20.62 | 1107 | 1104 | Linalool | Floral, Lily of the valley | 78-70-6 | ND | ND | 0.15 ± 0.02 b | ND | ND | 3.07 ± 0.28 a |
| 8 | 33.80 | 1584 | 1571 | Nerolidol | Green, Floral, Fruity aromas | 7212-44-4 | ND | ND | ND | 0.38 ± 0.04 b | ND | 0.97 ± 0.18 a |
| Esters (7) | 4.71 | 1.94 | 29.59 | 0.66 | 1.81 | 19.32 | ||||||
| 1 | 20.50 | 1107 | 1091 | Methyl benzoate | Honey, Flower | 93-58-3 | 1.67 ± 0.32 b | 0.27 ± 0.08 c | 5.27 ± 0.83 a | 0.57 ± 0.10 bc | 0.56 ± 0.05 bc | ND |
| 2 | 31.05 | 1398 | 1378 | Methyl 4-methoxybenzoate | Peppers, Herbs, Dried fruits | 121-98-2 | 1.40 ± 0.15 b | 1.47 ± 0.32 b | 21.11 ± 1.85 a | ND | ND | ND |
| 3 | 26.73 | 1220 | - | 2-Ethylhexyl acrylate | - | 103-11-7 | 1.63 ± 0.10 a | ND | ND | ND | ND | ND |
| 4 | 38.47 | 1975 | 1993 | Ethyl palmitate | Fragrance, Milk | 628-97-7 | ND | 0.20 ± 0.03 bc | ND | 0.09 ± 0.03 c | 0.56 ± 0.10 b | 3.50 ± 0.67 a |
| 5 | 3.23 | 596 | 605 | Ethyl acetate | Pineapple, Apple | 141-78-6 | ND | ND | 0.57 ± 0.06 a | ND | ND | ND |
| 6 | 40.31 | 2155 | 2159 | Ethyl linoleate | Fatty | 544-35-4 | ND | ND | 2.64 ± 0.16 b | ND | 0.69 ± 0.06 c | 10.61 ± 1.18 a |
| 7 | 40.22 | 2142 | 2149 | Ethyl oleate | Cocoa | 111-62-6 | ND | ND | ND | ND | ND | 4.54 ± 0.86 a |
| 8 | 36.11 | 1790 | 1793 | Ethyl myristate | Iris aroma, Fat | 124-06-1 | ND | ND | ND | ND | ND | 0.35 ± 0.07 a |
| 9 | 39.89 | 2104 | 2110 | Ethyl stearate | Slightly waxy, Irritating | 111-61-5 | ND | ND | ND | ND | ND | 0.32 ± 0.03 a |
| Ketones (9) | 15.06 | 0.29 | 1.14 | 5.76 | 0 | 3.76 | ||||||
| 1 | 10.48 | 894 | 889 | 2-Heptanone | Banana, Medicine | 110-43-0 | 3.35 ± 0.27 a | ND | ND | 1.42 ± 0.47 b | ND | ND |
| 2 | 31.81 | 1449 | 1458 | (E)-6,10-Dimethyl-5,9-undecadien-2-one | Green, Magnolia, Fruit | 3796-70-1 | ND | 0.29 ± 0.02 b | 1.14 ± 0.11 a | ND | ND | ND |
| 3 | 14.49 | 990 | 984 | 3-Octanone | Mushroom, Mould | 106-68-3 | ND | ND | ND | 3.30 ± 0.39 a | ND | ND |
| 4 | 29.66 | 1317 | - | 4’-Hydroxy-2’-Methylacetophenone | - | 875-59-2 | 11.71 ± 0.82 a | ND | ND | ND | ND | ND |
| 5 | 29.13 | 1293 | 1291 | 2-Undecanone | Waxy, Fruity | 112-12-9 | ND | ND | ND | 0.66 ± 0.08 b | ND | 1.32 ± 0.24 a |
| 6 | 17.71 | 1054 | 1037 | 3-Octen-2-one | Nut, Crushed bug | 1669-44-9 | ND | ND | ND | 0.38 ± 0.02 a | ND | ND |
| 7 | 33.30 | 1551 | - | massoia lactone | Coconut | 54814-64-1 | ND | ND | ND | ND | ND | 2.44 ± 0.14 a |
| Acids (5) | 0.00 | 1.18 | 4.55 | 0.38 | 18.99 | 9.22 | ||||||
| 1 | 38.47 | 1986 | 1975 | Palmitic acid | Waxy | 57-10-3 | ND | 1.18 ± 0.11 b | 4.55 ± 0.08 a | ND | 4.79 ± 0.46 a | 3.89 ± 0.32 a |
| 2 | 40.16 | 2134 | 2140 | Linoleic acid | Faint fatty | 60-33-3 | ND | ND | ND | ND | 8.39 ± 0.78 a | 3.30 ± 0.26 b |
| 3 | 25.87 | 1196 | 1191 | Octanoic acid | Cheese, Sweat, Spicy | 124-07-2 | ND | ND | ND | 0.38 ± 0.04 a | ND | ND |
| 4 | 40.44 | 2170 | 2180 | Stearic acid | Putrid | 57-11-4 | ND | ND | ND | ND | 1.65 ± 0.23 a | ND |
| 5 | 28.14 | 1263 | 1280 | Nonanoic acid | Green, Fat | 112-05-0 | ND | ND | ND | ND | 4.27 ± 0.64 a | 3.03 ± 0.07 a |
| Others (13) | 12.26 | 31.24 | 0.66 | 2.16 | 1.16 | 0.46 | ||||||
| 1 | 14.81 | 996 | 987 | 2-pentylfuran | Bean, Fruit | 3777-69-3 | 7.86 ± 0.42 a | 0.71 ± 0.11 b | 0.27 ± 0.05 b | 0.98 ± 0.16 b | ND | ND |
| 2 | 26.11 | 1201 | 1200 | Dodecane | Gasoline | 112-40-3 | 0.74 ± 0.11 a | 0.10 ± 0.02 b | ND | ND | ND | ND |
| 3 | 34.03 | 1605 | 1600 | n-Hexadecane | - | 544-76-3 | 1.09 ± 0.12 a | ND | ND | ND | ND | ND |
| 4 | 31.10 | 1408 | 1400 | Tetradecane | Alkane | 629-59-4 | 1.52 ± 0.34 a | 2.21 ± 0.28 a | ND | ND | ND | ND |
| 5 | 32.81 | 1519 | 1521- | 2,4-Di-tert-butylphenol | Leather | 96-76-4 | ND | 0.42 ± 0.10 b | ND | ND | 1.16 ± 0.39 a | 0.46 ± 0.11 b |
| 6 | 32.48 | 1505 | 1502 | (+)-Cuparene | - | 16982-00-6 | ND | ND | 0.39 ± 0.07 a | ND | ND | ND |
| 7 | 33.17 | 1542 | - | 3,5-di-tert-butylphenol | - | 1138-52-9 | ND | 0.34 ± 0.06 a | ND | ND | ND | ND |
| 8 | 26.52 | 1213 | - | 2,6-Dichloroanisole | - | 1984-65-2 | ND | ND | ND | 0.28 ± 0.03 a | ND | ND |
| 9 | 29.68 | 1319 | - | 4-Ethyl-3-nonen-5-yne | - | 74685-67-9 | ND | ND | ND | 0.56 ± 0.09 a | ND | ND |
| 10 | 32.29 | 1482 | 1483 | α-curcumene | Herb | 644-30-4 | 1.05 ± 0.06 a | ND | ND | ND | ND | ND |
| 11 | 29.99 | 1337 | - | Phenol, 5-ethenyl-2-methoxy- | - | 621-58-9 | ND | 27.47 ± 2.86 a | ND | ND | ND | ND |
| 12 | 29.35 | 1305 | 1315 | 2-Methylnaphthalene | Floral | 91-57-6 | ND | ND | ND | 0.19 ± 0.02 a | ND | ND |
| 13 | 3.95 | 630 | - | Ammonium acetate | - | 631-61-8 | ND | ND | ND | 0.16 ± 0.03 a | ND | ND |
Note: “RT”: Retention time; “RI”: Retention Index; “ND”: volatile compounds not detected. Volatile compounds were identified by comparing the RI and MS fragmentation patterns with mass spectra from the NIST17 library. Different superscript lowercase letters in a row (a–d) represent statistically significant differences between the mean values at p < 0.05 determined by one-way ANOVA. CAS# is an alias of CAS number which indicates the unique numerical identification number of a substance.