Elucidation of interactions between gelatin aggregates and hsian-tsao gum in aqueous solutions

Interactions between gelatin aggregates (G, 0.5 wt%) and an anionic polysaccharide hsian-tsao gum (HG, 0-0.25 wt%) in aqueous solutions were investigated at 25 °C using zeta potentiometry, turbidimetric analysis, dynamic light scattering, confocal laser scanning microscopy (CLSM), fluorescence spectra and circular dichroism measurements. The results indicated that soluble and insoluble G-HG complexes formed mainly through electrostatic interactions followed critical pH-dependent structure-forming events. The phase transition points (pH_φ1, pH_opt and pH_φ2) shifted to lower pH with HG increased, whereas pH_c kept constant. Conformational transitions of G from α-helix to β-sheet were promoted by interacting with HG, concurrent with changes in environment of hydrophobic residues. Additionally, CLSM evidenced phase transitions of G from homogeneity to separation occurred by interaction with HG, forming G-HG complexes with G centered and HG absorbed on the periphery. Findings aided in understanding interactions mechanism between G and HG to further apply HG in designing new food matrixes.