Table 5.
Independent variables and levels established through the central composite design for nuts roasting conditions
| Independent variables | Independent variables level | ||||
|---|---|---|---|---|---|
| Low | Medium | High | Axial (− α ) | Axial ( +α ) | |
| Roasting temperature (°C) | 100.0 | 140.0 | 180.0 | 74.68 | 205.32 |
| Roasting time (min) | 5.0 | 17.5 | 30.0 | −2.91 | 37.91 |
| pH | 5.0 | 6.0 | 7.0 | 4.367 | 7.633 |
Axial points allow for the estimation of the tuning parameters of a second-order model. CCD is afirst-order (2N) designs augmented by additional centre and axial points.