Optimization of Ultrasound-Assisted Extraction of Polyphenol Content from Zea mays Hairs (Waste)

Figure 7

Contour plots for the effect of independent variables on extraction yield. (a) Contour plot graph showing interaction between extraction time (X3) and ethanol concentration (X1); (b) contour plot graph showing interaction between solvent-to-material ratio (X2) and ethanol concentration (X1); (c) contour plot graph showing interaction between extraction time (X3) and solvent-to-material ratio (X2).

(a)

(b)

(c)