Abstract:In order to improve the solubility of protein in high temperature denatured defatted rice bran meal the optimal steam flash-explosion process conditions was studied. The single factor experiment was carried out with the factors of steam pressure，pressure residence time，moisture content，and particle size. The Box -Behnken test was designed according to the single factor test results，with the nitrogen dissolution index as evaluation index，and the optimal steam flash -explosion process conditions was determined by response surface analysis. The changes of physico-chemical properties of rice bran protein，after high temperature steam flash explosion process，were studied by scanning electron microscope（SEM），differential scanning calorimetry （DSC） and surface hydrophobicity measurement. The results showed that the optimum parameters were steam pressure 2.3 MPa，pressure residence time 210 s，moisture content 57 %，particle size 50 mesh，and the nitrogen dissolution index was 57.23 % under this condition ， which was 1.65 times higher than that before optimization. By steam- flash-explosion treatment，the agglomerate of rice bran was dispersed，the whole morphology was no longer maintained ，and the thermal stability and surface hydrophobicity of rice bran protein were significantly decreased. Steam flash-explosion-treatment can significantly improve the solubility of protein in high temperature denatured defatted rice bran meal.