Polygonatum cyrtonema polysaccharide as a modifier for soy protein isolate gel: Interaction, structural changes, and enhanced properties.

This study investigated the effects of Polygonatum cyrtonema polysaccharide (PCP) on the aggregation behavior, microstructure, and gel properties of soy protein isolate (SPI). At a PCP incorporation level of 3.0 %, the gel exhibited maximum hardness, springiness, and water retention capacity of 0.98 N, 2.83 mm, and 93.53 %, respectively. Non-covalent interactions between PCP and SPI induced conformational variations in the protein, resulting in fluorescence quenching and the creation of a more hydrophilic microenvironment around amino acid residues. Moreover, PCP triggered a notable rearrangement of the SPI's secondary structure, marked by a significant increase in α-helix and β-turn structures alongside a reduction in random coil structure. SPI gels containing PCP displayed a spatially homogeneous and densely packed microstructure, primarily resulting from enhanced hydrophobic interactions, hydrogen bonding, and disulfide bond formation. These structural modifications collectively enhanced the gel's quality, rheological properties and thermal stability, providing a theoretical basis for developing SPI-based foods.