highly significantP < 0.01
The interaction between H 2 O 2 ( X 11 ) and Novozym 435 catalyst amount ( X 12 ) and the interaction between H 2 O 2 ( X 11 ), and reaction time ( X 13 ) were significant ( P < 0.05), while its quadratic term of reaction time ( X 33 ) was highly significant ( P < 0.01).