Functional properties and structure of soluble dietary fiber obtained from rice bran with steam explosion treatment

Rice bran was modified by steam explosion (SE) treatment to investigate the effect of different steam pressure (0.4, 0.8, 1.2, 1.6, and 2.0 MPa) with rice bran through 60 mesh and rice bran pulverization (60, 80, and 100 mesh) with the steam pressure of 1.2 MPa on the functional properties and structure of soluble dietary fiber (SDF) from SE-treated rice bran. SE pretreatment enhanced glucose and cholesterol adsorption capacity, water-holding capacity, oil-holding capacity, lipase inhibition capacity and anti-oxidation properties of SDF. However, functional properties of SDF were adversely affected when steam pressure was 2.0 MPa or crushing degree of rice bran was 100 mesh. The results showed that some glycosidic and hydrogen bonds were broken, resulting in a porous honeycomb structure and decreased polymerization degree of the crystalline regions and relative crystallinity in SDF from SE-treated rice bran. In general, the optimum condition for obtaining better properties of SDF was treated for rice bran at the steam pressure of 1.2 MPa and sieve size of 60 mesh. This finding emphasizes essential information on SE treatment of rice bran in modifying the properties of SDF, which is helpful to the development and utilization of SDF from SE-treated rice bran.