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

Figure 6

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

(a)

(b)

(c)