Though rice proteins have been applied to improve the stability of phenolic compounds, it is unclear how rice proteins affect phenolic acid's digestion and bioavailability. This study investigated the consequences of protein-ferulic acid interactions in the gastrointestinal environment. Ferulic acid and rice proteins formed complexes at room temperature, both with and without laccase. Rice protein was reported to be able to prevent ferulic acid from degrading in simulated oral fluid and remain stable in gastrointestinal fluids. With the hydrolysis of pepsin and pancreatin, rice protein-ferulic acid complexes degraded and released ferulic acid. While digested ferulic acid's DPPH scavenging activity was dramatically reduced, it was retained for the rice protein-ferulic acid complex. Moreover, the permeability coefficient of ferulic acid was not affected. Thus, rice protein is a promising food matrix to protect ferulic acid in the digestive tract and maintain the antioxidant functions of ferulic acid.
Keywords: Ferulic acid; antioxidative activities; cell permeability; protein; rice protein.