Figure 3

Normal percentage probability plot for the studentized residuals for highest yield of %DPPHsc (a), %ABTSsc (e) and FRAP (i). Relationship between experimental and predicted value for highest yield of %DPPHsc (b), %ABTSsc (f) and FRAP (j). Response surface and contour plot showing the combined effects of methanol concentration (X1) and temperature (X2) for highest yield of %DPPHsc, %ABTSsc and FRAP when time and particle size were held at fixed level (c,g,k,d,h,l), respectively.