Effects of sodium tripolyphosphate modification on the structural, functional, and rheological properties of rice glutelin

In this study, rice glutelin isolated from glutinous rice was modified by sodium tripolyphosphate at different sodium tripolyphosphate concentrations (1%, 4%, 7%). The structural, functional and rheological properties of phosphorylated rice glutelin were investigated. The results indicated that phosphorylated rice glutelin samples showed small particle size and high absolute zeta potential values. Phosphorylation reaction was occurred between -OH and -NH2 groups in rice glutelin and sodium tripolyphosphate, as confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The particle surface of phosphorylated rice glutelin samples became very rough and exhibited some small convex and concave holes. Moreover, the solubility, emulsifying and foaming properties, thermal stability and apparent viscosity of phosphorylated rice glutelin samples were significantly increased. These results suggest that the solubility, emulsification and rheological properties of rice glutelin are significantly improved after phosphorylation, which will be beneficial to expand the application of rice glutelin in food industry.