gluten is as high as 80%(dry basis) in rice protein. Because it is an alkali-soluble protein, it severely limits rice protein as a high-quality hypoallergenic protein. The application of sexual plant protein in the food industry. To this end, this article studied the heat treatment of rice gluten in an alkaline solution (pH 12) at different temperatures (60, 80, 100°C) for 30 and 60 minutes. The results show that after heating gluten at 100°C for 60 minutes, its solubility at pH 7 is about 3 times higher than that of natural protein, its foaming ability is about 2 times higher, and it has better foam stability. The results of dynamic light scattering (DLS) and atomic force microscopy (AFM) show that heat treatment (100℃, 60min) reduces the size of gluten globular aggregates (about 100nm), reduces the disulfide bond content, and increases the net surface potential and hydrophobicity . Sodium dodecyl sulfate-polyacrylamide gel (SDS-PAGE) electrophoresis, ultraviolet-visible spectroscopy, intrinsic fluorescence spectroscopy and infrared spectroscopy analysis showed that heat treatment changed the primary, tertiary and secondary conformation of gluten. In addition, the small-angle X-ray scattering (SAXS) results show that the heat-treated gluten aggregates have greater flexibility. These changes in size and structure help to improve the functional properties of rice gluten after heat treatment, which means that the combination of alkali and heat treatment may improve the performance of rice protein. Related research results were published in Food Hydrocolloids with the title”Enhancing the solubility and foam ability of rice glutelin by heat treatment at pH12:insight into protein structure”. Meng Zhao, a graduate student of the School of Food Science and Engineering, Nanjing University of Finance and Economics, is the first author, and Dr. Wenfei Xiong and Professor Lifeng Wang are the corresponding authors. This research was funded by the National Key Research and Development Program (2016YFD0400201) and the National Natural Science Foundation of China (No. 31571766).
Figure 1. Different heat treatment effects on rice gluten dissolving ability (A, B) and foaming ability ( C), the influence of foam stability (D) and foam appearance (E); before heat treatment, protein is dissolved in pH 12 aqueous solution (5 mg/mL); in the figure 60-30/60, 80-30/60, 100 -30/60 means treatment at 60, 80, 100 ℃ for 30 and 60 minutes, respectively.
Figure 2. The effect of different heat treatments on the conformation of rice gluten. A is SDS-PAGE electrophoresis, B is ultraviolet spectrum, C is endogenous fluorescence spectrum, D is second derivative infrared spectrum; SAXS scattering intensity distribution (E) and Kratky diagram (F) of gluten under different heat treatment conditions.