between observed and predicted results for phytase activity reflected the accuracy and applicability of the design for process optimization (see Table 4). Figs. 9–11 show the response surface plots of phytase production.
Obviously, phytase yield varied significantly upon changing the glucose, peptone or tween 80 concentrations. It
indicated that the optimum values of each variable were identified based on the hump in the three dimensional or from the
central point of the corresponding contour plot. The statistical optimization resulted in about 9.8-fold compared to the non-optimized medium.