Table 1.
Central composite design (CCD) used in the first optimization approach and the proanthocyanidin yields under different combinations of extraction conditions.
| Proanthocyanidin Yield (mg CE/g FW) |
|||||
|---|---|---|---|---|---|
| Run Order | Ethanol (%) |
Extraction Time (h) | Solvent: Solid Ratio (v:w) | Grape Seeds | Grape Seed Powder |
| 1 | 20.24 (−1) | 62.86 (−1) | 33.92 (+1) | 13.17 | 11.19 |
| 2 | 79.76 (+1) | 177.14 (+1) | 16.07 (−1) | 12.63 | 9.37 |
| 3 | 79.76 (+1) | 62.86 (−1) | 16.07 (−1) | 10.58 | 9.97 |
| 4 | 50 (0) | 120 (0) | 25 (0) | 14.84 | 13.60 |
| 5 | 100 (+1.68) | 120 (0) | 25 (0) | 8.30 | 4.66 |
| 6 | 50 (0) | 120 (0) | 25 (0) | 14.30 | 13.92 |
| 7 | 0 (−1.68) | 120 (0) | 25 (0) | 6.81 | 1.58 |
| 8 | 79.76 (+1) | 177.14 (+1) | 33.92 (+1) | 13.11 | 11.51 |
| 9 | 20.24 (−1) | 177.14 (+1) | 16.07 (−1) | 9.99 | 4.84 |
| 10 | 50 (0) | 120 (0) | 25 (0) | 14.65 | 13.69 |
| 11 | 20.24 (−1) | 62.86 (−1) | 16.07 (−1) | 9.40 | 7.43 |
| 12 | 50 (0) | 120 (0) | 25 (0) | 14.61 | 13.94 |
| 13 | 20.24 (−1) | 177.14 (+1) | 33.92 (+1) | 12.56 | 10.22 |
| 14 | 79.76 (+1) | 62.86 (−1) | 33.92 (+1) | 11.13 | 10.31 |
| 15 | 50 (0) | 120 (0) | 25 (0) | 14.12 | 13.70 |
| 16 | 50 (0) | 24 (−1.68) | 25 (0) | 12.41 | 13.36 |
| 17 | 50 (0) | 120 (0) | 25 (0) | 15.10 | 13.78 |
| 18 | 50 (0) | 216 (+1.68) | 25 (0) | 15.19 | 11.95 |
| 19 | 50 (0) | 120 (0) | 40 (+1.68) | 16.40 | 15.20 |
| 20 | 50 (0) | 120 (0) | 10.00 (−1.68) | 12.13 | 10.28 |
Low-axial (−1.68), low (−1), center (0), high (+1), and high-axial (+1.68) levels of the three extraction parameters are indicated in brackets. mg CE/g FW, mg catechin equivalence/g fresh weight.