The ANOVA of the fitting results (Table 2) indicated
that both enzyme activity (X1) and pH (X2) influenced the concentration of glutamic acid (CGA) and also the concentration of
aspartic acid (CAA) significantly (P ¼ 0.0001 < 0.05). The P value of
X3 ¼ 0.181 and X4 ¼ 0.228, both >0.05 for CGA indicated that CGA
was not significantly influenced by both hydrolysis temperature
and time. Similarly, the P values of X3 ¼ 0.924 and X4 ¼ 0.992, both
>0.05 for CAA indicated that the CAA was not significantly influenced
by both hydrolysis temperature and time.