Modification of insoluble dietary fiber from rice bran with dynamic high pressure microfluidization: Cd(II) adsorption capacity and behavior

The aim of the study is to improve the physicochemical and Cd(II) adsorption properties of rice bran insoluble dietary fiber (RBIDF). Dynamic high pressure microfluidization (DHPM) (0–150 MPa for 2 times) was investigated as a modification process for RBIDF, determining its effects on physicochemical, structural and Cd(II) adsorption properties. After a 30 MPa treatment, the flake-like surface of RBIDF changed into a fluffy and slightly expanded morphology. However, DHPM-treated RBIDFs at 60, 90 MPa were fragmented and separated into smaller chips. DHPM increased the RBIDF specific surface area and total negative charge. Among all samples, DHPM-treated RBIDF at 150 MPa exhibited the highest Cd(II) adsorption capacity (60.5 μmol/g at pH 2.0), which was 1.46 times that of the untreated sample. Cd(II) adsorption was well described by the pseudo-second-order kinetics and Langmuir isotherms models, and Cd(II) removal rate was as high as 56.9% in the simulated small intestine. In conclusion, DHPM shows great potential for enhancing the Cd(II) adsorption capacity by RBIDF. This research deals with the modification of RBIDF by DHPM treatments. The treatments at 120 or 150 MPa obviously increased Cd(II) adsorption capacity by unfolding the stiff structure to expose more oxygen-containing functional groups. DHPM is thus a safe and eco-friendly method to improve the physicochemical and adsorbent properties of RBIDF, which is a promising ingredient for use in food applications.