Kinetics of the hydrolysis of polysaccharide galacturonic acid and neutral sugars chains from flaxseed mucilage

Different hydrolysis procedures of flaxseed polysaccharides (chemical and enzymatic) were carried out with H2SO4, HCl and TFA at different acid concentrations (0.2, 1 and 2 M) and temperatures (80 and 100°C). Enzymatic and combined chemical and enzymatic hydrolyses of polysaccharide from flaxseed mucilage were also studied. Acid hydrolysis conditions (2 M H2SO4, 4 h, 100°C) are required to quantify total monosaccharide content of flaxseed mucilage. The enzymatic pathway (Pectinex™ Ultra SP) limits sugar destruction during hydrolysis, but it is also insufficient for complete depolymerization. The combination of the two treatments, i.e. moderate chemical hydrolysis (0.2 M H2SO4, 80°C, 48 h) combined with enzymatic hydrolysis is not more effective compared to chemical hydrolysis in drastic conditions (2 M H2SO4 at 100°C). The strong interaction between the neutral and acid fractions of flaxseed mucilage may hinder total release of sugar residues. Physical treatment prior to the hydrolysis could be necessary to achieve complete depolymerisation of flaxseed mucilage.