Kinetics of Hydrolysis of Cassava Starch (Manihot esculanta): Effect of Addition of K and Mg Ions on Reducing Sugar

Hargono Hargono, Noer Abyor Handayani, Aji Prasetyaningrum

Abstract: Sweet cassava (Manihot esculanta) can produce reducing sugars through enzymatic hydrolysis. The addition of K and Mg ions can increase reducing sugars concentration. The objective of this study was effect the addition of K and Mg ions on reducing sugars concentration as well as to study the kinetics of hydrolysis. Experiments were carried out using100, 200, 300 g/L of starch; 1, 1.5% (w/v) of enzyme, and 100 ppm of K and Mg ions. The hydrolysis was conducted at 30?C with the StargenTM 002 at pH 4 for 18 hours. The results showed that the presence of enzyme along with starch were able to significantly increase the production of reducing sugars. The addition of K and Mg ions increased the reducing sugar to 38.79% and 78.25%. The best reducing sugar concentration of 68.32 g/L was obtained at 200 g/L starch concentration, 1.5% (w/w) enzyme concentration with the addition of Mg ions for 12 hours. Kinetic studies show that this hydrolysis phenomenon follows the Michaelis-Menten equation with a Km value of 98.8, 107.32 and 106.77 g/L and a Vmax value of 7.69, 9.26 and 15.63g/L.h, respectively, so that the addition of K and Mg ions can increase enzyme activity.

Keywords: cassava, enzymatic hydrolysis, K and of Mg ions, kinetic studies