Table 3.
Phenolic compounds (mg 100 g−1 d.m.) quantified in wheat samples by HPLC-ESI-QTOF-MS. Different letters in the same row indicate significant differences (p < 0.05). Abbreviations: WG: wheat grain; WB: wheat bran, FP: free phenolic fraction, BP: bound phenolic fraction; n.d.: not detected; LOD: limit of detection.
| Class | Sub-Class | Compound | OG | OB | SO | OH1 | OH2 | |||
|---|---|---|---|---|---|---|---|---|---|---|
| FP | BP | FP | BP | FP | BP | |||||
| Phenolic acids | Hydroxybenzoic acids | Protocatechuic acid | 1.05 ± 0.04 a | n.d. | n.d. | n.d. | n.d. | 1.71 ± 0.17 b | n.d. | n.d. |
| Hydroxybenzoic acid | n.d. | 0.75 ± 0.01 c | 0.53 ± 0.02 a | n.d. | n.d. | 0.66 ± 0.10 b | n.d. | 0.74 c | ||
| Hydroxycinnamic acids | Ferulic acid | 0.36 + 0.01 | 28.30 ± 1.56 c | 0.50 + 0.13 | 213.76 ± 4.39 e | n.d. | 32.36 ± 3.09 d | 6.15 ± 0.87b | 3.38 a | |
| p-Coumaric acid | n.d. | n.d. | n.d. | 130.67 ± 1.43 c | n.d. | n.d. | 11.47 ± 2.11 b | 7.32 a | ||
| Sinapic acid | n.d. | 2.93 ± 0.18 b | n.d. | n.d. | n.d. | 2.50 ± 0.14 a | n.d. | n.d. | ||
| Avenanthramide C | n.d. | n.d. | 0.21 ± 0.02 a | n.d. | 13.40 ± 0.34 b | 0.19 ± 0.04 a | n.d. | n.d. | ||
| Avenanthramide 2p | n.d. | n.d. | 1.58 ± 0.14 a | n.d. | 14.35 ± 0.27 b | n.d. | n.d. | n.d. | ||
| Avenanthramide 2f | 0.23 ± 0.07 a | n.d. | 1.48 ± 0.10 b | n.d. | 19.24 ± 0.19d | 1.67 ± 0.01 c | n.d. | n.d. | ||
| Diferulic isomer 1 | n.d. | 4.42 ± 0.22 b | n.d. | n.d. | n.d. | 3.80 ± 0.38 a | n.d. | n.d. | ||
| Diferulic isomer 2 | n.d. | 5.02 ± 0.63 b | n.d. | n.d. | n.d. | 3.85 ± 0.38 a | n.d. | n.d. | ||
| Diferulic isomer 4 | n.d. | 5.70 ± 0.39 a | n.d. | n.d. | n.d. | 8.35 ± 0.82 b | n.d. | n.d. | ||
| Diferulic isomer 5 | n.d. | 6.83 ± 0.59 a | n.d. | n.d. | n.d. | 7.30 ± 0.62 a | n.d. | n.d. | ||
| Diferulic isomer 6 | n.d. | 0.74 ± 0.06 a | n.d. | n.d. | n.d. | n.d. | n.d. | n.d. | ||
| Caffeic acid | 2.32 ± 0.01 c | 1.50 ± 0.11 a | n.d. | 6.42 ± 0.26 e | n.d. | 3.44 ± 0.41 d | 2.41 ± 0.25 c | 1.72 b | ||
| Isoferulic acid | n.d. | 3.36 ± 0.67 a | n.d. | n.d. | n.d. | 2.96 ± 0.39 a | n.d. | n.d. | ||
| 1-O-Sinapoyl-beta-D-glucose | 1.55 ± 0.02 a | n.d. | n.d. | n.d. | 2.45 ± 0.02 b | n.d. | n.d. | n.d. | ||
| Flavonoids | Flavones | Apigenin-6-C-arabinoside-8-C-hexoside III | n.d. | n.d. | <LOD | n.d. | <LOD | n.d. | n.d. | n.d. |
| Others | Hydroxybenzaldehide acids | 4-Hydroxybenzaldehyde | n.d. | 1.10 ± 0.11 a | 4.17 ± 0.06 c | 27.88 ± 1.44 e | n.d. | 1.71 ± 0.11 b | 9.10 ± 1.05 d | 9.91 d |