Effect of Rice Bran Protein on the Foaming Properties and Foaming Characteristics of Rice Bran Protein-Sodium Caseinate and Rice Bran Protein Nanoparticles-Sodium Caseinate.

ABSTRACT

Rice bran, a byproduct of rice milling, comprises 12-14% protein. The foaming properties and associated mechanisms of the composite rice bran protein system were not well studied. In this study, a composite protein system composed of rice bran protein (RBP)-sodium caseinate (NaCas) and rice bran protein nanoparticles (RBPNs)-sodium caseinate (NaCas) was investigated. The results showed that the synergistic effect of RBP and NaCas increased the foaming stability of the composite solution up to 83.77 ± 2.75%. Moreover, the foaming capacity and foaming stability of the RBPNs-NaCas composite solution were up to 177.50 ± 3.53% and 80.28 ± 0.39%, respectively. The physicochemical properties results revealed that the particle size volume peaks of RBP-NaCas and RBPNs-NaCas were mainly concentrated at 55.7 nm and 197.1 nm, and RBPNs-NaCas showed a wider single peak particle size distribution. The ζ-potential values of RBP-NaCas and RBPNs-NaCas were changed to -35.5 ± 0.07 mV and -27.2 ± 0.28 mV after complexation. The apparent viscosity and consistency factor of RBP-NaCas decreased by 31.1% compared to RBP, while RBPNs-NaCas displayed similar parameters to the single proteins. The interfacial rheological test showed that RBP and RBPNs can significantly improve the interfacial properties of NaCas by enhancing the interfacial interaction and the interfacial viscoelastic modulus of composite proteins, which is conducive to the stability of the foam system. The outcome of the study provided a theoretical basis for RBP and RBPNs to partially replace NaCas in the processing of foamed food.