Low-viscosity dietary fiber production by enzymatic hydrolysis of galactomannan from Caesalpinia pulcherrima seeds: Optimization and physicochemical characterization

This study optimizes the enzymatic hydrolysis of galactomannan from Caesalpinia pulcherrima seeds to produce a low-viscosity dietary fiber. The effects of cellulase concentration (4.17-9.83 U/g of galactomannan) and hydrolysis time (98-392 min) on two response variables were evaluated using RSM. Some physical and chemical characteristics were determined on the hydrolysate selected in comparison with galactomannan. Both factors negatively affected the intrinsic viscosity, although positively influenced (p < .05) the reducing sugar content. The optimum condition was 9 U/g with 300 min, with 1.28 dl/g of intrinsic viscosity and 1.33% of reducing sugar. The hydrolysis increased total dietary fiber (1.9%) and soluble dietary fiber (2.8%) contents and decreased M-n from 26.4 x 10(4) to 3.2 x 10(4) g/mol. Thermal and scanning electron microscope analysis suggested internal and external molecular changes, respectively. However, FT-IR, H-1, and C-13-NMR spectra showed characteristic chemical bonds and a mannose/galactose ratio of 2:1. This hydrolyzed galactomannan is suitable as a low-viscose dietary fiber with potential applications in food industry. Novelty Impact Statement Galactomannan from seeds of Caesalpinia pulcherrima was successfully hydrolyzed. Enzymatic hydrolysis caused a decrease of 87.72% in molecular mass. The hydrolyzed product remained high in dietary fiber (84.3%).