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 beta-conglycinin (7S)/glycinin (11S) in acid-heating with CaCl2 concentration (0-200 mM) was explored. Fibril formation kinetics results showed the fastest fibril formation rate and the most fibrils with 80 mM CaCl2 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 CaCl2 concentration increasing from 0 to 80 mM. When CaCl2 addition was above 80 mM, zeta-potential, surface hydrophobicity (H0) 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 CaCl2 has preferable antioxidant property and no cytotoxicity. The study provided a basis optimizing SPI fibrillation in food industry.