Effect of Different Valence Metal Ions on Rice Protein Fibrillation: Binding Mechanism, Structural Characterization and Rheology

In this study, the interactions between metal ions of different valences (Na+, Ca2+, Al3+) and rice protein (RP) and their effects on rice protein fibrillation were investigated. The results showed that adding metal ions could shorten the time of protein fibrillation and increase fibril yield. The fluorescence results showed that high-valent metal ions were more likely to destroy the hydration layer on the surface of the protein, showing higher fluorescence intensity. The dynamic binding of metal ions to proteins promoted fibrils elongation. Moreover, The high-valent metal ions have more binding sites and larger binding constants with proteins. As the morphological studies showed that the length of fibrils increased to more than 1 & mu;m after the addition of metal ions. The rheological results revealed that the viscosity of fibrils formed under the mediation of high-valent metal ions was enhanced and the storage modulus was higher than the loss modulus, indicating stronger molecular forces between fibrils and better elastic properties. This study provided a method for regulating RP fibrillation and meanwhile provided new insights for the application of RP.