Table 4.

Box–Behnken design matrix with real coded values of three variables to optimize β-glucosidase production by the Neofusicoccum parvum strain F7.

Run no	Variable level			Enzyme activity (U/ml)
	Incubation time (days)	Incubation temperature (°C)	Glycerol (%)	Observed	Predicted
1	− (8)	− (20)	0 (0.5)	0.37	0.81
2	+ (12)	0 (30)	0 (0.5)	2.51	2.07
3	− (8)	+ (40)	0 (0.5)	0.02	-0.69
4	+ (12)	+ (40)	0 (0.5)	0.03	0.56
5	− (8)	0 (30)	− (0.25)	0.55	0.52
6	+ (12)	0 (30)	− (0.25)	1.92	1.78
7	− (8)	0 (40)	+ (0.75)	0.45	0.54
8	+ (12)	+ (40)	+ (0.75)	0.03	1.79
9	0 (10)	− (20)	− (0.25)	1.97	1.72
10	0 (10)	+ (40)	− (0.25)	0.01	0.18
11	0 (10)	− (20)	+ (0.75)	1.57	1.73
12	0 (10)	+ (40)	+ (0.75)	0.02	0.19
13	0 (10)	0 (30)	0 (0.5)	1.14	1.38
14	0 (10)	0 (30)	0 (0.5)	1.18	1.41
15	0 (10)	0 (30)	0 (0.5)	1.48	1.44
16	0 (10)	0 (30)	0 (0.5)	1.31	1.48

Real values: (), coded values: symbolized as +, 0 and – for high, optimal and low, respectively.