Table 2.
Changes in the relative concentration of the key volatile compounds in unfermented control and fermented moromi samples (μg/L).
| LRI * | Volatile Compounds | Identification Method | Unfermented Control | Fermented Samples | |||
|---|---|---|---|---|---|---|---|
| Control-0 | Control-30 | T0-30 | W5-30 | T0W5-30 | |||
| Alcohols | |||||||
| 893 | Methanol | MS, LRI | ND | 59.67 ± 6.84 a | 52.99 ± 7.85 b | 49.77 ± 3.05 bc | 47.47 ± 2.64 c |
| 912 | Ethanol | MS, LRI | 159.17 ± 5.41 c | 491.69 ± 13.51 b | 509.91 ± 18.72 b | 591.81 ± 4.36 a | 568.45 ± 11.25 a |
| 1439 | 1-Octen-3-ol | MS, LRI | ND | 29.43 ± 0.84 c | 32.82 ± 0.13 b | 36.68 ± 12.34 a | 38.86 ± 0.67 a |
| 1911 | 2-Phenylethanol | MS, LRI | 0.63 ± 0.08 d | 11.23 ± 3.66 c | 17.17 ± 0.16 b | 18.29 ± 0.03 b | 20.63 ± 1.36 a |
| Subtotal | 159.80 | 592.02 | 612.89 | 696.55 | 675.41 | ||
| Percentage (%) | 95.51 | 89.87 | 85.27 | 84.42 | 78.72 | ||
| Acids | |||||||
| 1445 | Acetic acid | MS, LRI | ND | 18.38 ± 3.31 d | 23.37 ± 0.43 c | 25.37 ± 2.10 b | 35.47 ± 2.78 a |
| Subtotal | ND | 18.38 | 23.37 | 25.37 | 35.47 | ||
| Percentage (%) | ND | 2.79 | 3.25 | 3.07 | 4.13 | ||
| Aldehydes | |||||||
| 915 | 2-Methylbutyraldehyde | MS, LRI | 6.02 ± 1.73 d | 9.28 ± 0.42 c | 18.79 ± 1.25 b | 18.62 ± 0.72 b | 20.37 ± 0.57 a |
| 922 | Isovaleraldehyde | MS, LRI | 1.50 ± 2.54 d | 9.48 ± 0.97 c | 18.90 ± 1.08 b | 19.43 ± 1.07 b | 25.29 ± 1.31 a |
| 1177 | 3-Methylthiopropionaldehyde | MS, LRI | ND | 4.29 ± 0.41 d | 5.31 ± 0.31 c | 6.46 ± 1.13 b | 9.64 ± 0.21 a |
| 1515 | Benzaldehyde | MS, LRI | ND | 10.45 ± 2.20 d | 15.23 ± 1.41 c | 18.08 ± 2.11 b | 24.19 ± 1.06 a |
| Subtotal | 7.52 | 33.5 | 58.23 | 62.59 | 79.49 | ||
| Percentage (%) | 4.49 | 5.09 | 8.10 | 7.59 | 9.27 | ||
| Esters | |||||||
| 960 | Ethyl isobutyrate | MS, LRI | ND | 0.59 ± 0.18 d | 0.93 ± 0.09 c | 1.15 ± 0.12 b | 2.22 ± 0.23 a |
| 1755 | Methyl phenylacetate | MS, LRI | ND | 1.89 ± 0.22 c | 1.98 ± 0.17 c | 4.89 ± 0.07 b | 6.79 ± 0.17 a |
| 2224 | Ethyl palmitate | MS, LRI | ND | 5.93 ± 5.16 c | 6.09 ± 1.72 c | 15.24 ± 0.55 b | 21.13 ± 1.42 a |
| Subtotal | ND | 8.41 | 9.00 | 21.28 | 30.14 | ||
| Percentage (%) | ND | 1.28 | 1.25 | 2.58 | 3.51 | ||
| Phenols | |||||||
| 1940 | HEMF ** | MS, LRI | ND | ND | 5.74 ± 0.08 b | 3.75 ± 0.05 c | 9.93 ± 0.68 a |
| 1862 | Guaiacol | MS, LRI | ND | 2.47 ± 0.27 d | 5.48 ± 0.25 c | 7.35 ± 0.26 b | 12.06 ± 0.05 a |
| 1988 | Methyl maltol | MS, LRI | ND | 3.96 ± 2.64 c | 4.02 ± 0.94 c | 8.21 ± 0.53 b | 15.45 ± 0.82 a |
| Subtotal | ND | 6.43 | 15.24 | 19.31 | 37.44 | ||
| Percentage (%) | ND | 0.98 | 2.12 | 2.34 | 4.36 | ||
| Total | 167.32 | 658.74 | 718.73 | 825.1 | 857.95 | ||
* LRI: linear retention index; ** 4-Hydroxy-2 (or 5)-ethyl-5 (or 2)-methyl-3 (2H)-furanone; Different letters in the same row indicate significant differences at p ≤ 0.05. Values are the mean ± standard deviation of three independent replicates (n = 3).