Table 3.

Results of statistical (CCD) analysis for optimization of fermentation parameters

Model term	Coefficient estimate	Computed t value	p value	Confidence level (%)
(a) Model coefficient estimated by regressions
Intercept	0.637714	184.607	0*	100
Temperature (X1)	0.008208	4.4	0*	100
Medium pH (X2)	−0.021208	−11.368	0*	100
Shaking (X3)	−0.006125	−3.283	0.005*	99.5
Inoculum size (X4)	0.004958	2.658	0.017*	98.3
Temperature × temperature	−0.028564	−16.713	0*	100
pH × pH	−0.007314	−4.279	0.001*	99.9
Shaking × shaking	0.008811	5.155	0*	100
Inoculum size × inoculum size	−0.002689	−1.573	0.135	86.5
Temperature × medium pH (X1 × X2)	0.003563	1.559	0.139	86.1
Temperature × shaking (X1 × X3)	−0.007438	−3.255	0.005*	99.5
Temperature × inoculum size (X1 × X4)	0.005938	2.599	0.019*	98.1
Medium pH × shaking (X2 × X3)	0.001187	0.520	0.610	39
Medium × inoculum size pH (X2 × X4)	0.000313	0.137	0.893	10.7
Shaking × inoculum size (X3 × X4)	0.000063	0.027	0.979	2.1

Source	DF	SS	MS	F value	p value
					prob > F
(b) ANOVA for quadratic model
Regression	14	0.043830	0.003131	37.48	0
Linear	4	0.013903	0.003476	41.61	0
Square	4	0.028251	0.007063	84.55	0
Interaction	6	0.001676	0.000279	3.34	0.025
Residual (error)	16	0.001337	0.000084
Lack of fit	10	0.001133	0.000113	3.34	0.077
Pure error	6	0.000203	0.000034
Total	30	0.045167

DF degrees of freedom, SS sum of squares, MS mean square

* Significant p values, p ≤ 0.05; R² = 0.9701; predicted R² = 0.9422; adjusted R² = 0.8473