Table 4.
Polynomial equations calculated using the RSM program for extraction conditions of Zea mays L.
| Response variables | Second order polynomial equationsa | R2 | p-value |
|---|---|---|---|
| Total polyphenol content (mg GAE/g) | YTPC = 12.967917 + 0.236917X1 + 0.119583X2-0.184667X3-1.221042X4-0.001699X12-0.000781X1X2 + 0.021901X2
2-0.013988X1X3 + 0.003563 X2X3 + 0.012854X3 2 + 0.16953X1X4 2-0.021797X2X4-0.007281X3X4+ 0.029538X4 2 |
0.935 | 0.0001 |
| Total anthocyanin content (mg C3GE/100 g) | YTAC = 412.389167 + 0.248000X1 + 4.349167X2-14.648667X3-23.737500X4-0.027356X12-0.058562X1X2 + 0.341094X2 2-0.079975X1X3-0.072875X2X3 + 0.288875X3 2 + 0.279406X1X4 2-0.230156X2X4 + 0.099687X3X4 + 0.388867X4 2 | 0.917 | 0.0001 |
| Extraction yield (%) | YEY = 29.279167-0.538500X1-0.842500X2-0.823000X3-0.010833X4 + 0.006002X12-0.007188X1X2 + 0.059427X2 2 + 0.004625X1X3-0.003125X2X3 + 0.010508X3 2 + 0.004219X1X4 2 + 0.014844X2X4 + 0.003437X3X4-0.0077997X4 2 | 0.887 | 0.0001 |
aX1, extraction temperature (°C); X2, extraction time (hour); X3, solid-liquid ratio (%); X4, solvent volume (1:X)