Table 3.

Variables in the Box-Behnken design.

Factor	Actual and Coded Levels Used for the Conditions
	Low (−1)	Medium (0)	High (+1)
A = Water content (%)	30	40	50
B = Time (min)	2	4	6
C = Pressure	300	400	500
D = Liquid to solid ratio	100	110	120
Dependent variable	Constrains
R1 = Baicalin/(mg/g)	Maximize