Hydrophobic aggregation via partial Gal removal affects solution characteristics and fine structure of tamarind kernel polysaccharides

The role of molecular aggregation was further investigated on solution and structural characteristics of tamarind kernel polysaccharides (TKPs vs. CTKPs) via partial degalactosylation. In addition to the distinctive aggregation-disaggregation behaviors observed when complexed with Congo red, TKPs and CTKPs in the capillary viscous behaviors behaved as relatively ordered semi-flexible coil, and showed augmented intermolecular interactions during partial degalactosylation. Concretely, the sheet-like structure evolving from ordered architecture contributed more to the conformational asymmetry, where hydrophobic microdomains were sufficiently promoted and solute-solute interactions dominated. Meanwhile, the stiffer semi-flexible primary aggregates with dwindling chain stiffness exhibited stronger and larger-scale hydrophobic aggregations. Considering the multiple interplays of hydrophobic interactions, the role of hydrophobic aggregation could be dissimilar between TKPs and CTKPs, which manifested in the hierarchical change of microstructure as well as susceptibility of structural oligosaccharide motifs to partial degalactosylation, thereby favoring hydrophobic aggregation in varying degrees. Finally, the mechanism of hydrophobic aggregation under partial degalactosylation was further illustrated, which was expected to promote tailored valorizations of tamarind kernel polysaccharide in more potential fields.