Optimization of Enzymatic Parameters for Enhancing Branch Density and Flow Properties of Sweet Potato Starch

Enhancing the branch density of starch through enzymatic modification is critical for improving its functional properties in various industrial applications. This study optimized the sequential enzymatic treatment of sweet potato starch using α-amylase (AA), β-amylase (BA), and transglucosidase (TG) to maximize the degree of branching (DB). Response Surface Methodology (RSM) was employed to evaluate the synergistic effects of enzyme concentrations and hydrolysis durations, identifying optimal conditions: AA (20.00 U/g, 9.01 h), BA (3.00 U/g, 5.03 h), and TG (2179.06 U/g, 9.00 h). Under these conditions, the DB reached 53.38%, which was within 2.53% of the predicted value (55.91%). Structural analyses via XRD and FTIR revealed reduced crystallinity, indicating disrupted molecular order. The modified starches exhibited significantly enhanced solubility compared to native starch, particularly those with DB values above 40%, attributed to shorter glucan chains and inhibited amylose recrystallization. Rheological studies demonstrated shear-thinning behavior and diminished viscoelasticity, suggesting improved flow properties for low-viscosity applications. These findings highlight the efficacy of enzymatic combinatorial modification in tailoring starch functionality, offering a promising approach for producing high-branch-density starches with enhanced flow and solubility properties for use in sauces, beverages, and biodegradable films.