Kinetics of Corn Starch Hydrolysis by Enzyme Catalysis Under Microwave Irradiation

The kinetics of the corn starch hydrolysis catalyzed by α-amylase and glucoamylase in microwave irradiation,comparing with the water bath heating,was studied.The effects of pH value,reaction temperature,substrate concentration,the amount of α-amylase and glucoamylase on the initial reaction velocity were investigated.It is showed that the initial velocity of the starch hydrolysis in microwave irradiation is about 20% more than that obtained by the water bath heating.Based on the Michealis equation,the Michealis constant Km,the maximum reaction velocity νm and the inhibition constant Ki were investigated.In the microwave irradiation,the Km and νm of the starch hydrolysis catalyzed by α-amylase are 3 922.76 g/L and 1.72×10-3 mol/(mL·min),and the Km and νm by glucoamylase are 173.31 g/L and 3.289×10-5 mol/(mL·min).While by the water bath heating,the Km and νm of the starch hydrolysis catalyzed by α-amylase are 312.03 g/L and 1.21×10-4 mol/(mL·min),and the Km and νm by glucoamylase are 16.14 g/L and 3.89×10-6 mol/(mL·min).The inhibition constant of glucoamylase in the microwave irradiation is less than that by the water bath heating.