Enzyme–Acid Hydrolysis: An Effective Pretreatment Method for the Monosaccharide Composition Analysis of Acidic Polysaccharides

Accurate monosaccharide composition analysis was a prerequisite for studying the structure and function of polysaccharides. This study evaluated three one-step hydrolysis methods (H₂SO₄, trifluoroacetic acid (TFA), and Driselase) on polysaccharides with varying uronic acid contents and developed an enzyme--acid hydrolysis protocol for acidic polysaccharides. Results demonstrated that neutral tamarind seed polysaccharide (TSP) was effectively hydrolyzed by H₂SO₄/TFA with hydrolysis yields exceeding 97%. However, acidic polysaccharides, including peach gum polysaccharide (PGP), phyllanthus emblica polysaccharide (PEP), and passion fruit pectin (PFP), showed low hydrolysis yields with one-step methods. A Driselase-H₂SO₄ hydrolysis strategy was then established involving Driselase pretreatment, followed by H₂SO₄ hydrolysis at optimized conditions (0.5-2.0 M, 60-90 min). This protocol increased the hydrolysis yields of PGP, PEP, and PFP to 97.41%, 86.17%, and 87.06%, respectively, with high repeatability and precision. These results were significantly higher than those from one-step hydrolysis methods, effectively improving the accuracy of the monosaccharide composition analysis for acidic polysaccharides.