Direct Enzymatic Production of Oligosaccharide Mixtures from Sugar Beet Pulp: Experimental Evaluation and Mathematical Modeling

The potential of sugar beet pulp as raw material for neutral and acidic oligosaccharide production by direct enzymatic treatment was evaluated. The effect of the polygalacturonase to solid ratio (PGaseSR), cellulase activity to polygalacturonase activity ratio (CPGaseR), and reaction time (t) on several dependent variables (selected to quantify the mass of recovered liquors, the conversion of each polysaccharide into monosaccharides, and the conversion of each polysaccharide into oligomers) was studied. Mathematical models suitable for reproducing and predicting the experimental results were also developed. Operational conditions leading to a maximum oligomer production were calculated from models being PGaseSR = 10 U/g, CPGaseR = 0.725 filter paper units/U, and t = 12.82 h. Under these conditions, the models predicted that 906 kg of liquors containing 26.7 kg of oligosaccharides can be obtained from 100 kg of SBP, the distribution being as follows: 5.9 kg of glucooligosaccharides, 2.4 kg of galactooligosaccharides, 9.7 kg of arabinooligosaccharides, and 8.7 kg of oligogalacturonides. Therefore, this study demonstrated that pectic oligomers (for which prebiotic properties have been reported) can be obtained from SBP at high yield by direct enzymatic hydrolysis using mixtures of cellulases and pectinases.