Functional, physicochemical and structural properties of soluble dietary fiber from rice bran with extrusion cooking treatment

The effects of extrusion cooking treatment with different parameters (when the screw speed was 250 rpm/min and the material moisture was 17 %, the extrusion cooking temperature were 100 °C, 120 °C, 140 °C, 160 °C, 180 °C, respectively; when the screw speed was 250 rpm/min and the extrusion cooking temperature was 160 °C, the material moisture were 11 %, 14 %, 17 %, 20 %, 23 %, respectively) on the functional, physicochemical and structural properties of soluble dietary fiber (SDF) from rice bran were investigated. The water and oil retention capacity (WRC and ORC), water solubility (WS), in vitro binding capacities (bile salt, cholesterol and glucose binding capacity) and antioxidant capacities of SDF were higher when extrusion cooking temperatures were 100 °C and 120 °C. The in vitro binding capacities and antioxidant capacities of SDF were higher when material moisture contents were 11 % and 14 %. However, the ORC, in vitro binding capacities and antioxidant capacities decreased when extrusion cooking temperature was higher than 140 °C and material moisture was higher than 14 %. The results of FT-IR spectrum indicated that the structure of SDF from rice bran was changed after extrusion cooking treatment. The extrusion cooking treatment at low temperature and low material moisture was more beneficial to the properties of SDF. This study may provide basic information for the utilization of SDF from rice bran with extrusion cooking treatment.