Table 2.
Content of the identified phenolic compounds in Touriga Nacional (TN) and Tinta Roriz (TR) extracts obtained through subcritical water extraction (SWE) at 125 and 250 °C. Results were expressed as mean ± standard deviations (milligrams of compound/100g dw, n=3).
| Compound | TN | TR | ||
|---|---|---|---|---|
| 125 °C | 250 °C | 125 °C | 250 °C | |
| Phenolic acids | ||||
| Gallic acid | 60.1 ± 3.0 | 891 ± 45 | 74.2 ± 3.7 | 1066 ± 53 |
| Protocatechuic acid | 33.8 ± 1.7 | 14.5 ± 0.7 | 33.4 ± 1.7 | 21.2 ± 1.1 |
| 4-hydroxyphenilacetic acid | 16.8 ± 0.8 | 62.6 ± 3.1 | 49.2 ± 2.5 | 134 ± 7 |
| 4-hydroxybenzoic acid | 9.2 ± 0.5 | 22.6 ± 1.1 | 8.4 ± 0.4 | 44.9 ± 2.2 |
| 4-hydroxybenzaldehyde | 4.9 ± 0.2 | 7.5 ± 0.4 | 4.7 ± 0.2 | 9.8 ± 0.5 |
| Chlorogenic acid | 6.2 ± 0.3 | 23.2 ± 1.2 | 7.4 ± 0.4 | 44.3 ± 2.2 |
| Vanillic acid | 15.0 ± 0.7 | 15.6 ± 0.8 | 13.5 ± 0.7 | 31.6 ± 1.6 |
| Caffeic acid | 14.9 ± 0.7 | 13.6 ± 0.7 | 14.4 ± 0.7 | 19.6 ± 1.0 |
| Syringic acid | ND a | 37.9 ± 1.9 | <LOD b | 65.6 ± 3.3 |
| p-coumaric acid | 17.2 ± 0.9 | 16.0 ± 0.8 | 22.9 ± 1.1 | 21.7 ± 1.1 |
| Ferulic acid | 21.9 ± 1.1 | 18.9 ± 0.9 | 24.5 ± 1.2 | 19.6 ± 1.0 |
| Sinapic acid | 17.1 ± 0.9 | 14.4 ± 0.7 | 22.0 ± 1.0 | 12.2 ± 0.6 |
| Cinnamic acid | 11.1 ± 0.6 | 8.1 ± 0.4 | 12.2 ± 0.6 | 11.1 ± 0.5 |
| ∑Phenolic acids | 228 ± 11 | 1145 ± 57 | 286 ± 14 | 1502 ± 75 |
| Flavanols | ||||
| (+)-Catechin | 102 ± 5 | 181 ± 9 | 245 ± 12 | 216 ± 11 |
| (-)-Epicatechin | 3.9 ± 0.2 | 3.1 ± 0.2 | 17.2 ± 0.9 | 14.6 ± 0.7 |
| ∑Flavanols | 106 ± 5 | 184 ± 9 | 262 ± 13 | 231 ± 12 |
| Flavanones | ||||
| Naringin | <LOD | 8.6 ± 0.4 | <LOD | 14.7 ± 0.7 |
| Naringenin | 4.5 ± 0.2 | 2.4 ± 0.1 | 6.1 ± 0.3 | 3.3 ± 0.2 |
| ∑Flavanones | 4.5 ± 0.2 | 11.0 ± 0.6 | 6.1 ± 0.3 | 18.0 ± 0.9 |
| Flavonols | ||||
| Rutin | 3.1 ± 0.2 | 9.2 ± 0.5 | 1.4 ± 0.1 | 15.4 ± 0.8 |
| Quercetin-3-O-glucopyranoside | 4.4 ± 0.2 | 5.2 ± 0.3 | 4.1 ± 0.2 | 10.7 ± 0.5 |
| Myricetin | 84.3 ± 4.2 | 14.6 ± 0.7 | 86.4 ± 4.3 | 16.2 ± 0.8 |
| Kaempferol-3-O-glucoside | 9.4 ± 0.5 | ND | 10.1 ± 0.5 | 8.6 ± 0.4 |
| Kaempferol-3-O-rutinoside | 4.3 ± 0.2 | 2.3 ± 0.1 | 4.7 ± 0.2 | 7.0 ± 0.4 |
| Quercetin | 40.9 ± 2.0 | 24.9 ± 1.2 | 40.7 ± 2.0 | 30.8 ± 1.5 |
| Kaempferol | 34.6 ± 1.7 | 23.2 ± 1.2 | 41.6 ± 2.1 | 24.2 ± 1.2 |
| ∑Flavonols | 181 ± 9 | 79.4 ± 4.0 | 189 ± 9 | 113 ± 6 |
| Stilbenes | ||||
| Resveratrol | 8.0 ± 0.4 | 15.8 ± 0.8 | 10.5 ± 0.5 | 13.1 ± 0.7 |
| ∑Stilbenes | 8.0 ± 0.4 | 15.8 ± 0.8 | 10.5 ± 0.5 | 13.1 ± 0.7 |
| Others | ||||
| Phloridzin | <LOD | 3.7 ± 0.2 | <LOD | 8.0 ± 0.4 |
| Phloretin | ND | <LOD | <LOD | <LOD |
| ∑Others | 0.0 ± 0.0 | 3.7 ± 0.2 | 0.0 ± 0.0 | 8.0 ± 0.4 |
| ∑All phenolic compounds | 527 | 1440 | 755 | 1884 |
a ND: not detected; b LOD: limit of detection.