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

Table 1

Levels of variables for the experimental design.

Independent variable	Symbol	Coded levels
		−1	0	1
Ethanol/water (%)	X1	50	60	70
Solvent/material ratio (mL/g)	X2	10	15	20
Time (min)	X3	40	45	50