Table 2.
Analysis of variance of the quadratic model, adjusted to the extraction of total anthocyanins. The ranges studied for each parameter were: methanol (50–100%), pH (2–7), temperature (50–100 °C), and sample–solvent ratio (0.5 g/10 mL–0.5 g/20 mL).
| Variable | Source | Coefficient | Sum of Squares | Degrees of Freedom | Mean Square | F-Value | p-Value |
|---|---|---|---|---|---|---|---|
| Model | 445.11 | 14 | 31.79 | 4.05 | 0.0100 | ||
| Methanol | X1 | 0.249033 | 0.7442 | 1 | 0.7442 | 0.0949 | 0.7633 |
| pH | X2 | −0.207067 | 0.5145 | 1 | 0.5145 | 0.0656 | 0.8022 |
| Temperature | X3 | −2.56032 | 78.66 | 1 | 78.66 | 10.03 | 0.0081 |
| Ratio | X4 | −0.92215 | 10.20 | 1 | 10.20 | 1.30 | 0.2762 |
| Methanol-pH | X1X2 | 5.98483 | 15.51 | 1 | 15.51 | 1.98 | 0.1850 |
| Methanol-Temperature | X1X3 | −1.9692 | 21.20 | 1 | 21.20 | 2.70 | 0.1260 |
| Methanol-Ratio | X1X4 | 2.3022 | 0.6398 | 1 | 0.6398 | 0.0816 | 0.7800 |
| pH-Temperature | X2X3 | 0.39995 | 41.29 | 1 | 41.29 | 5.27 | 0.0406 |
| pH-Ratio | X2X4 | −0.758496 | 0.5627 | 1 | 0.5627 | 0.0718 | 0.7933 |
| Temperature-Ratio | X3X4 | 3.21277 | 9.76 | 1 | 9.76 | 1.24 | 0.2864 |
| Methanol-Methanol | X12 | 0.375075 | 191.03 | 1 | 191.03 | 24.36 | 0.0003 |
| pH-pH | X22 | −0.830096 | 3.07 | 1 | 3.07 | 0.3913 | 0.5433 |
| Temperature-Temperature | X32 | −1.56213 | 3.67 | 1 | 3.67 | 0.4687 | 0.5066 |
| Ratio-Ratio | X42 | 1.0868 | 6.30 | 1 | 6.30 | 0.8034 | 0.3877 |
| Residual | 18.6496 | 94.10 | 12 | 7.84 | |||
| Lack of Fit | 87.43 | 10 | 8.74 | 2.62 | 0.3076 | ||
| Pure Error | 6.67 | 2 | 3.33 | ||||
| Total | 539.21 | 26 |