Effect of starch degradation induced by extruded pregelatinization treatment on the quality of gluten-free brown rice bread

There is considerable interest in preparing high-quality gluten-free bread. The effect of the molecular structure of extruded pregelatinization starch on the dough's rheological properties and the brown rice bread's quality was investigated. Extruded rice starch (ERS) was prepared with various added moisture contents of 20 % (ERS20), 30 % (ERS30), and 40 % (ERS40), respectively. ERS had smaller molecular weight and more short branched chains as the moisture content decreased. The dough elasticity and deformation resistance were improved with the ERS supplementation and in the order of ERS40 > ERS30 > ERS20 at the same level. Fortification with ERS improved the gluten-free brown rice bread quality. Compared to the control group, breadcrumbs supplemented with ERS20 at the 10 % level showed an increase in cell density from 17.87 cm-2 to 28.32 cm-2, a decrease in mean cell size from 1.22 mm2 to 0.81 mm2, and no significant change in cell area fraction. In addition, the specific volume increased from 1.50 cm3/g to 2.04 cm3/g, the hardness decreased from 14.34 N to 6.28 N, and the springiness increased from 0.56 to 0.74. The addition of extruded pregelatinization starches with smaller molecular weights and higher proportions of short chains is promising for preparing high-quality gluten-free bread.