Table 2.
Polyphenolic compounds detected by HPLC from walnut green husks samples.
| Polyphenol | Detection | Control Extraction | Optimized Extraction | |||
|---|---|---|---|---|---|---|
| DAD (nm) | FLD (nm) | OH | CH | OH | CH | |
| Gallic acid | 272 | - | ✓ | ✓ | ✓ | ✓ |
| Protocatechuic acid | 260–290 | - | ✓ | ✓ | ✓ | ✓ |
| Catechin | 278 | 280–318 | ✓ | ✓ | - | ✓ |
| Caffeic acid | 322 | - | ✓ | - | - | - |
| Ferulic acid | 322 | 332–445 | ✓ | ✓ | ✓ | ✓ |
| Polydatin | 306–318 | 320–395 | ✓ | - | - | - |
| Hesperetin | 284 | - | - | - | - | - |
| Resveratrol | 306–318 | 323–390 | - | - | - | - |
| Quercetin | 254–370 | - | ✓ | ✓ | - | - |
| Myricetin | 250–370 | - | - | - | - | - |
| Kaempferol | 270–366 | - | ✓ | ✓ | - | - |
| Hesperidin | 288 | - | ✓ | ✓ | - | - |
| Juglone | 235–275 | - | - | - | ✓ | ✓ |
OH: ripe walnuts green husk (open husk); CH: unripe walnuts green husk (closed husk); DAD: diode array detector; FLD: fluorescence detector.