Table 3: ANOVA for the response surface quadratic polynomial model.

Source Sum of squares df Mean square value value Significance Model 0.03 14 20.16 <0.00 **a —pH 1 1.11 0.39   —temperature 1 70.40 <0.00 ** —E/S 1 48.84 <0.00 ** —incubation period 1 102.04 <0.00 ** 1 0.43 0.52   1 2.34 0.15   1 1.15 0.30   1 0.81 0.38   1 1.86 0.19   1 7.79 0.01 ****c 1 2.62 0.13   1 3.62 0.08   1 12.32 0.00 ***b 1 22.72 0.00 ** Residual 15       Lack of fit 10 0.43 0.88   Pure error 5       Cor. total 0.03 29         Std. Dev.     -squared 0.95   Mean 0.29     Adj. -squared 0.90   C.V.%     Pred. -squared 0.83   PRESS     Adeq. precisior 18.81

df: degree of freedom. aSignificance at 0.001 level. bSignificance at 0.01 level. cSignificance at 0.05 level