Table 3.
Phenolic compounds and glutathione content of liquid extracts during extraction and after filtration at the end of the process.
| Compound | Extraction | After Filtration | ||
|---|---|---|---|---|
| 0 h | 48 h | 96 h | ||
| Content (mg/L) | ||||
| Phenolic acids | ||||
| Caffeic acid | nd | nd | nd | nd |
| Caftaric acid | 31.63 ± 1.98 d | 59.00 ± 2.89 c | 86.65 ± 4.49 a | 135.3 ± 3.36 a |
| Coumaric acid | nd | nd | nd | nd |
| Coutaric acid | 0.30 ± 0.05 d | 10.19 ± 0.18 c | 36.62 ± 0.41 b | 74.41 ± 3.49 b |
| Ferulic acid | nd | nd | nd | nd |
| Fertaric acid | 0.09 ± 0.01 d | 2.85 ± 0.07 c | 8.41 ± 0.06 b | 33.06 ± 0.96 a |
| Gallic acid | nd | nd | nd | 0.06 ± 0.00 |
| Flavonols | ||||
| Quercetin | 0.06 ± 0.06 a | 0.05 ± 0.00 a | 0.06 ± 0.00 a | 0.05 ± 0.00 a |
| Quercetin 3-O-hexoside | 0.72 ± 0.18 c | 4.89 ± 0.37 b | 12.86 ± 0.09 a | 12.33 ± 0.46 b |
| Quercetin 3-O-glucuronide | 1.59 ± 0.20 d | 8.99 ± 0.75 c | 32.51 ± 0.60 a | 23.54 ± 0.69 b |
| Rutin | 0.17 ± 0.04 c | 0.61 ± 0.05 b | 0.83 ± 0.03 a | 0.86 ± 0.03 a |
| Isorhamnetin | nd | nd | nd | nd |
| Kaempferol | nd | nd | nd | nd |
| Kaempferol 3-O-glucoside | 0.34 ± 0.01 c | 1.03 ± 0.04 b | 2.64 ± 0.05 a | 2.43 ± 0.14 a |
| Myricetin | 0.05 ± 0.00 a | 0.05 ± 0.00 a | 0.05 ± 0.00 a | 0.04 ± 0.02 a |
| Myricetin-hexoside | nd | nd | nd | nd |
| Piceatannol | nd | nd | nd | nd |
| Flavan-3-ols | ||||
| (+)-Catechin | 0.10 ± 0.03 d | 17.96 ± 0.12 c | 80.20 ± 1.18 b | 156.31±1.29 a |
| (−)-Epicatechin | nd | 0.49 ± 0.09 c | 7.35 ± 0.18 b | 17.21 ± 0.42 a |
| Epicatechin-O-gallate | nd | nd | 0.12 ± 0.01 a | 0.15 ± 0.01 a |
| Procyanidins | ||||
| Procyanidin B1 | nd | 3.04 ± 0.05 c | 9.22 ± 0.08 b | 10.30 ± 0.15 a |
| Procyanidin B2 | 0.19 ± 0.05 d | 6.79 ± 0.05 c | 9.22 ± 0.08 b | 17.71 ± 0.15 a |
| Glutathione | ||||
| GSH | nd | nd | nd | nd |
| Grape reaction product-GRP | 1.97 ± 0.16 c | 6.23 ± 0.81 b | 7.48 ± 0.92 a | 6.39 ± 0.75 b |
| GSSG | 1.08 ± 0.06 ab | 1.03 ± 0.05 b | 1.18 ± 0.08 a | 1.14 ± 0.09 ab |
GSH, reduced glutathione; grape reaction product-GRP, 2-S-Glutathionyl caftaric acid; GSSG, oxidized glutathione; nd, not detectable. Values are the mean ± SD (n = 3). Different letters indicate significantly different values among the columns (p ≤ 0.05).