Soluble dietary fiber and polyphenol complex in lotus root: Preparation, interaction and identification

In order to further determine the interaction between polysaccharides and polyphenols, the complex of soluble dietary fiber (SDF) and two phenols were prepared. According to the results, at the conditions of pH = 4, temperature = 60 °C, concentration ratio of polysaccharide and phenol = 4:1, the maximum adsorption of catechin and gallic acid in the SDF complex was 155.74 and 134.05 mg/g, respectively. Due to UV-Vis and FT-IR analysis, it could be speculated that the interaction between SDF and phenols resulted in chemical combination. Furthermore, the monosaccharide composition and molecular weight distribution of SDF were significantly altered after conjugated with phenols. However, it showed no significant difference between two different SDF-phenol complexes, referring to GC and GPC data. The surface of SDF-phenol complex was loose with uniform arrangement, while the physical mixture surface was porous with irregular holes and cracks. Both SDF-CC and SDF-GA complex indicated higher thermal stability than the mixtures by TGA analysis.