A by-product of the rice milling process, rice bran contains four different types of protein: albumin, globulin, prolamin, and glutelin. These proteins are widely known for being hypoallergenic and having nutritional benefits. In order to increase the value of rice bran, the protein was extracted via deep eutectic solvent (DES). Response Surface Methodology (RSM) was used to assess the impact of three operational conditions, including temperature, extraction duration, and the ratio of rice bran to DES, on the yield of rice bran protein after the precipitates were converted into powder form by freeze drying. At optimal working conditions, which were 60 °C, 2 h, and a 1:9 ratio of rice bran to DES, the method’s results showed that the highest extracted protein of rice bran was 16.254%. Several techniques, including Fourier transform infrared spectroscopy (FTIR) and Kjeldahl studies, have been used to demonstrate the presence of protein in rice bran powder. In the rice bran protein (RBP), amine (1640.70 cm−1), alcohol (3229.74 cm−1), and alkane (2925.37 cm−1) were all detected using FTIR analysis. Furthermore, Kjeldahl analysis revealed that 15.61% of the rice bran powder’s protein content is present. In conclusion, rice bran’s value as a functional meal can be increased by adding protein through the use of a deep eutectic solvent called green solvent.
