Table 6.
Polynomial equations and statistical parameters describing the effects of the independent variables considered on EAP, EAF, and the antioxidant potential measured by DPPH free-radical scavenging potential and FRAP, calculated after implementation of a 30-full factorial, central composite experimental design
| Response | Second-order polynomial equation | R 2 | P |
| EAP | 4.97−0.46X 1+0.076X 2+0.22X 3+0.52X 4+0.041X 1 X 2+0.068X 1 X 3+0.028X 1 X 4+0.00248X 2 X 3−0.14X 2 X 4−0.051X 3 X 4−0.57X 1 2+0.015X 2 2−0.26X 3 2+0.038X 4 2 | 0.9992 | <0.0001 |
| EAF | 2.96−0.26X 1+0.062X 2+0.18X 3−0.051X 4+0.063X 1 X 2+0.004131X 1 X 3+0.008234X 1 X 4+0.023X 2 X 3−0.075X 2 X 4−0.054X 3 X 4−0.34X 1 2−0.001526X 2 2+0.045X 3 2+0.005301X 4 2 | 0.9852 | <0.0001 |
| DPPH | 55.10332−1.44464X 1+0.558671X 2+2.214841X 3+6.072034X 4+0.947847X 1 X 2−0.16304X 1 X 3−0.40907X 1 X 4+0.115876X 2 X 3−0.81115X 2 X 4+1.715618X 3 X 4−10.9751X 1 2−0.04567X 2 2−2.02506X 3 2−3.78615X 4 2 | 0.9929 | <0.0001 |
| FRAP | 15.73672−0.77406X 1−0.02637X 2+0.856915X 3+1.37589X 4+0.121812X 1 X 2−0.03062X 1 X 3+0.332969X 1 X 4+0.053478X 2 X 3−0.2474X 2 X 4+0.045085X 3 X 4−1.77457X 1 2−0.34329X 2 2−0.93265X 3 2−0.205364X 4 2 | 0.9916 | <0.0001 |
X 1: ethanol concentration; X 2: extraction time; X 3: extraction temperature; X 4: number of extraction cycles