The optimization study of α-amylase activity based on central composite design-response surface methodology by dinitrosalicylic acid method.
The optimum conditions of an α-amylase activity were experimentally investigated in details comparing with those of using a response surface methodology (RSM). Its optimum activity was achieved with 0.5 concentration unit of α-amylase and 1.0% (w/v) starch concentration in phosphate buffer solution pH 6.9 at 37°C for 10 min. The α-amylase activity was monitored by dinitrosalicylic acid method based on the measurement of maltose. The enzymatic activity was then statistically optimized using RSM, alternatively to focus on the effects of pH buffer solution, incubation temperature and incubation time on the yield of maltose. A quadratic regression model that related the yield of maltose concentration (response) to three basic factors was developed using Design-Expert software. Regression analysis revealed that the maximum concentration of maltose (0.915 mg/mL) could be reached with the buffer solution pH 7.3 at 39°C for 10 min. The high value of the adjusted R-square of the regression (0.9255) also demonstrates the regression equation providing a good model to fit the data obtained.