Optimization of Bioactive Ingredient Extraction from Chinese Herbal Medicine Glycyrrhiza glabra: A Comparative Study of Three Optimization Models

Table 1

Effective factors and levels for glycyrrhizic acid extraction from Glycyrrhiza glabra.

Coded; levels	Ammonia concentration (%); (A)	Ethanol concentration (%); (B)	Return time (h); (C)	Liquid-solid ratio; (D)
2	0.70	70	2.50	12.0 : 1
1	0.65	65	2.25	11.5 : 1
0	0.60	60	2.00	11.0 : 1
	0.55	55	1.75	10.5 : 1
	0.50	50	1.50	10.0 : 1
	= 0.60	= 60	= 2.00	= 11.0 : 1

Note. For the independent variable , is actual value at the central point and is the step change of the independent variable corresponding to a unit variation of the dimensionless value.