KINETICS AND OPTIMISATION OF ENZYMATIC HYDROLYSIS OF STARCH FROM CORN COB VIA RESPONSE SURFACE METHODOLOGY

The increasing demand for renewable energy and bio-based products has heightened the need for sustainable utilization of agricultural residues, among which corn cob is abundant and rich in starch that can serve as a low-cost feedstock for fermentable sugar production. Despite its potential, the enzymatic hydrolysis of corn cob starch is often limited by suboptimal process conditions and inadequate kinetic data, which restrict large-scale application. This study therefore investigated the kinetics and optimisation of enzymatic hydrolysis of starch extracted from corn cob using α-amylase. Response Surface Methodology (RSM) was employed to evaluate the combined effects of enzyme concentration, pH, and reaction time on glucose yield. Among the models tested, the reduced cubic model was selected because it provided the best statistical performance, with high R² (0.9966) and adjusted R² (0.9907), significant model terms, and a non-significant lack of fit, making it the most reliable predictor of glucose yield. Experimental results showed that enzyme concentration and hydrolysis time were the most significant factors, with optimum conditions achieved at 5.596 mg/mL enzyme concentration, pH 6.117, and 89.667 minutes, yielding 99.61% glucose. Validation runs confirmed the accuracy of the model with experimental yields ranging from 98.6% to 98.9%. Kinetic analysis revealed that the hydrolysis followed a fractional reaction order (n = 0.56), while Michaelis–Menten parameters were determined as Vmax = 0.368 mg/mL•min and Km = 10.44 mg/mL, indicating efficient catalysis and good enzyme–substrate affinity. FTIR analysis of the hydrolysate confirmed glucose formation through characteristic O–H, C–O, and anomeric absorption bands. These findings demonstrate that α-amylase can effectively hydrolyze corn cob starch and that RSM, with the reduced cubic model, is a robust and reliable tool for process optimisation.