Effects of CaCl2 concentration on fibrils formation and characteristics of soybean protein isolate and β-conglycinin/glycinin

In this study, fibrillation of soybean protein isolate (SPI) and β-conglycinin (7S)/glycinin (11S) in acid-heating with CaCl 2 concentration (0–200 mM) was explored. Fibril formation kinetics results showed the fastest fibril formation rate and the most fibrils with 80 mM CaCl 2 addition. Fourier-transform infrared (FTIR) spectroscopy, size distribution and Transmission electron microscopy (TEM) results demonstrated SPI fibril structure became more complete and occurred entanglement with CaCl 2 concentration increasing from 0 to 80 mM. When CaCl 2 addition was above 80 mM, ζ-potential, surface hydrophobicity ( H 0 ) and free sulphydryl groups determination proved hydrophobic interaction among fibril built-units was hindered by charges shielded effect, and basic units of 11S were more exposed, aggregate morphology were changed to thicker fibrils or amorphous aggregates. The whole system with CaCl 2 has preferable antioxidant property and no cytotoxicity. The study provided a basis for optimizing SPI fibrillation in food industry. • Soybean protein isolate (SPI) fibril formation was improved in certain CaCl 2 concentration (80 mM). • Glycinin (11S) takes main responsibility in SPI fibrils transition affected by ionic strength. • Fibril system with CaCl 2 addition results in excellent biological activity.