Y =+β β0 ∑ ∑+i xi βij xx+i j ∑βii xi2 (1) where Y is the predicted value, represented by the enzy- matic activity; β0 is the constant term; βi is the linear co- efficient; βij is the interaction coefficient; βii is the quad- ratic coefficient; and xi and xj are the independent vari- ables in the coded values. The significance of all terms in the polynomial function was assessed statistically using the F-value at a probability (p) of 0.05. The model was then used to generate response surfaces and contour curves to determine the optimal operating ranges of the independent variables.