Improving solubility of rice protein powder by modifying its physicochemical properties by ultrasound-assisted protein-glutaminase

The effect of ultrasound-assisted protein-glutaminase (PG) deamidation on the physicochemical properties of rice protein (RP) was investigated. After ultrasound pretreatment, the degree of deamidation of RP reached the highest of 60.4 % at deamidating for 16 h. With the deamidating time increasing, the particle size of RP became smaller and the absolute value of zeta-potential gradually increased. For functional properties of RP, ultrasoundassisted PG deamidation improved the foaming capacity, emulsifying capacity and oil-holding capacity of RP. Based on the ameliorative physicochemical properties of RP, the properties of rice protein powder (RPP) were further determined. The solubility of RPP was significantly improved, increased by 102.6 % at 90 degrees C compared with the non-treated. Meanwhile, the antioxidant activity and flavor of RPP under PG deamidation were remarkably improved. In vitro digestibility of RPP also increased significantly. These results illustrated that PG deamidation could be an efficient method for improving the properties of proteins.