Effect of enrichment with stabilized rice bran and extrusion process on gelatinization and retrogradation properties of rice starch

Rice starch (RS) and blend of rice starch with 10% w/w of stabilized rice bran (SRB) were subjected to extrusion process in a co-rotating twin-screw extruder. The effect of SRB addition and extrusion on gelatinization and retrogradation properties of RS was investigated. The results obtained from the rapid visco analyzer (RVA) showed a significant decrease (p< 0.05) in viscosity of the extruded RS compared to the untreated RS. In addition, the viscosity was more decreased after enrichment of RS with SRB and extrusion. A similar decrease trend in gelatinization enthalpy (Delta H-gel) of RS was also observed from data of the differential scanning calorimetry (DSC). On the other hand, the enrichment with SRB and extrusion led to significant changes in the crystalline structure of RS as observed from the X-ray diffraction (XRD). Furthermore, the enrichment with SRB and extrusion generated a fibrous and porous structured starch gel with lower retrogradation rate, higher water-holding capacity, and less syneresis during storage at 4 degrees C for 7 days. Therefore, SRB can be recommended as functional food ingredient for enrichment and producing rice starch-based extruded snacks and ready-to-eat food products.