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Table 3 Experimental range and values of the independent variables in the central composite design for optimization of extraction conditions

From: Optimization of extraction parameters of PTP1β (protein tyrosine phosphatase 1β), inhibitory polyphenols, and anthocyanins from Zea mays L. using response surface methodology (RSM)

No. Independent Response variables
X1a X2 X3 X4 Y1b Y2 Y3
1 30 (-1) 6 (-1) 25 (-1) 12 (-1) 5.91 55.16 6.00
2 50 (1) 6 (-1) 25 (-1) 12 (-1) 3.40 32.06 7.65
3 30 (-1) 10 (1) 25 (-1) 12 (-1) 6.55 65.20 6.00
4 50 (1) 10 (1) 25 (-1) 12 (-1) 5.47 47.47 6.70
5 30 (-1) 6 (-1) 35 (1) 12 (-1) 6.32 66.17 5.85
6 50 (1) 6 (-1) 35 (1) 12 (-1) 2.04 16.61 8.50
7 30 (-1) 10 (1) 35 (1) 12 (-1) 8.08 77.94 6.15
8 50 (1) 10 (1) 35 (1) 12 (-1) 3.70 34.71 7.30
9 30 (-1) 6 (-1) 25 (-1) 12 (-1) 4.42 41.02 6.30
10 50 (1) 6 (-1) 25 (-1) 20 (1) 6.64 67.21 7.75
11 30 (-1) 10 (1) 25 (-1) 20 (1) 6.33 63.36 6.25
12 50 (1) 10 (1) 25 (-1) 20 (1) 6.47 65.81 7.10
13 30 (-1) 6 (-1) 35 (1) 20 (1) 5.75 58.94 6.35
14 50 (1) 6 (-1) 35 (1) 20 (1) 3.62 70.81 9.25
15 30 (-1) 10 (1) 35 (1) 20 (1) 6.30 64.96 6.35
16 50 (1) 10 (1) 35 (1) 20 (1) 4.67 69.92 9.00
17 20 (-2) 8 (0) 30 (0) 16 (0) 3.41 20.63 5.75
18 60 (2) 8 (0) 30 (0) 16 (0) 3.80 24.07 9.10
19 40 (0) 4 (-2) 30 (0) 16 (0) 4.64 40.02 5.95
20 40 (0) 12 (2) 30 (0) 16 (0) 4.63 37.48 6.00
21 40 (0) 8 (0) 20 (-2) 16 (0) 6.22 52.90 6.40
22 40 (0) 8 (0) 40 (2) 16 (0) 4.92 71.46 5.75
23 40 (0) 8 (0) 30 (0) 8 (-2) 6.63 60.04 2.70
24 40 (0) 8 (0) 30 (0) 24 (+2) 5.72 56.32 6.35
25 40 (0) 8 (0) 30 (0) 16 (0) 4.95 45.34 5.75
26 40 (0) 8 (0) 30 (0) 16 (0) 4.34 35.13 5.78
27 40 (0) 8 (0) 30 (0) 16 (0) 4.28 40.88 5.73
  1. aX1, extraction temperature (°C); X2, extraction time (hour); X3, solid-liquid ratio (%); X4, solvent volume (1:X)
  2. bY1, total polyphenol content (mg GAE/g); Y2, total anthocyanin content (mg C3GE/100 g) Y3, extraction yield (%)