Effect of Steam Flash Explosion on Physicochemical and Emulsifying Properties of High-Temperature Rice Bran Meal Protein

Abstract

High-temperature rice bran meal (HTRBM) is a valuable plant protein resource derived from heat-stabilized rice bran after oil extraction. Steam flash explosion (SFE) is a promising method for protein modification and has been shown to be effective in improving the properties of a variety of proteins. However, the effects of SFE on the Maillard reaction and emulsification of HTRBM remain poorly understood. This research evaluated how different SFE conditions affect the browning degree, physicochemical properties, solubility, emulsifying properties, thermal stability, zeta potential, and particle size of rice bran protein. Samples were labeled as follows: Sample 0 (SFE-untreated HTRBM), Sample 1 (0.8 MPa/140 s), Sample 2 (0.8 MPa/180 s), Sample 3 (1.25 MPa/90 s), Sample 4 (1.25 MPa/180 s), Sample 5 (1.7 MPa/90 s), and Sample 6 (1.7 MPa/180 s). Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy, differential scanning calorimetry (DSC), and other methods were employed to measure the aforementioned properties. The results revealed a substantial elevation in the browning degree of rice bran protein after SFE treatment, with A294 increasing by 82.3% and A420 increasing by 46.3% in Sample 4. The solubility and emulsifying properties exhibited notable enhancements, with an increase of 122.48% in solubility (Sample 5), and 26.51% and 26.58% increment in emulsifying activity index (EAI) and emulsifying stability index (ESI), respectively (Sample 3). FTIR and fluorescence spectra revealed the introduction of sugar groups into rice bran protein molecules, resulting in the Maillard reaction. The observed reduction in particle size and rise in zeta potential of rice bran protein emulsions, along with the reduction in denaturation temperature after SFE treatments, further confirmed the significant enhancements in physicochemical and emulsifying properties of HTRBM, thereby enhancing the utilization value of rice bran protein. This study provides a theoretical basis for the development and utilization of HTRBM and its protein.