Rice Protein Hydrolysis and Precipitation

Rice protein was obtained through precipitation per the method of Chen et al.^{45 (link)}. In brief, rice protein was enzymatically hydrolyzed with a 2:100 (v/v) enzyme-to-substrate ratio to obtain hydrolysates. Protease (Alcalase, EC 3.4.21.62, serine endo-peptidase, 2.4 AU-A/g; Healthmate, Changhua, Taiwan) was used and the hydrolysis conditions involved setting pH 8.0 at 50 ± 5 °C. After a 4-h reaction period, the protease was inactivated through heating at 85 °C for 15 min. After centrifugation (5000 rpm, 4 °C) for 15 min, the supernatant was lyophilized and stored at − 20 °C before use.