Structural and functional properties of soy protein isolates from different cultivars

To investigate the structural and functional properties of soy protein isolates (SPIs) derived from different natural soybean cultivars, while avoiding interference from artificial modifications, SPIs were extracted from seven different cultivars. Their composition, structure, and functional characteristics were systematically analysed. The results revealed significant differences among the samples. The 11S/7S ratios ranged from 1.04 to 1.65. The relative contents of secondary structural elements were as follows: α-helix (19.45-26.28 %), β-sheet (33.97-39.61 %), β-turn (19.17-25.67 %), and random coil (12.62-20.77 %). It was observed that the 11S/7S ratio influenced protein thermal stability. SPIs with smaller particle sizes exhibited higher apparent viscosity and improved emulsion uniformity. A higher absolute zeta potential enhanced electrostatic repulsion, inhibited aggregation, and contributed to emulsion stability. Correlation analysis indicated a significant negative correlation between 7S and 11S contents, as well as between foam stability and particle size. These findings provide a theoretical foundation for the functional screening of soybean cultivars and the development of plant-based protein foods, as well as valuable insights into the structural and functional characteristics of soy protein isolates.