Partial Enzymatic Hydrolysis of Glucomannan and Its Mathematical Model

The study of enzymatic hydrolysis of glucomannan (GM) was currently limited to obtain low molecular weight glucomannan, and was not specifically studied for spray drying feed applications. This research aimed to investigate the effect of enzyme concentration and duration of enzymatic hydrolysis of GM on the characteristics of hydrolyzed glucomannan (HGM). Moreover, the kinetic models of viscosity reduction in enzymatic hydrolysis of glucomannan were also studied. To achieve the goal, the GM was hydrolyzed using various enzyme concentrations (5 to 20 mg/l) for 300 min. Profiles of viscosity, average molecular weight (Mw), degree of polymerization, and antioxidant activity of HGM were observed. The kinetics of viscosity reduction was modeled with 1^st-order kinetics, 2^nd-order model, and Mahammad's order. An enzyme concentration of 20 mg/l (1% GM solution) was the fastest to reach the desired viscosity for spray drying feed purposes. The model of n^th-order was the best fitted to the viscosity reduction with R² equal to 0.9935, so the constants k = 1.1842 (Pa.s n^-1.t)^-1 and n = 0.6328 are obtained. The hydrolysis improved the antioxidant activity of HGM as the enzyme concentration increases. This antioxidant result highlighted the advantage of using HGM for coating and encapsulating the active compound which also offers oxidation protection.