Functionality of pre-cooked whole-grain corn, rice and sorghum flours for gluten-free bread

Extruded whole grain flours of corn, sorghum, and parboiled brown rice (PBR) and their blends were used to produce gluten-free (GF) multigrain bread. To determine the functionality of the flours, paste viscosity, farinography and oscillatory rheometry were evaluated as rheological methods, and for the bread, the texture profile, baking loss and specific volume of the breads were determined. The paste properties evidenced changes in the starch structure of the extruded samples, but these were not severe due to the absence of cold viscosity (CV) and formation of peak viscosity (PV), which evidenced the swelling capacity of the starch granules. The functionality of the samples was demonstrated by the increase in water absorption and farinographic consistency (PM), as well as by the development of dough viscoelasticity with continuous elastic (G ') and viscous (G '') moduli when measured by oscillatory rheometry. The GF breads produced showed specific volume increases from 53.8 to 91.7% compared to the control, as well as high crumb hardness. However, the cereal blends did not generate significant increases in specific volume between samples (P < 0.05), but those made with higher proportions of extruded sorghum flour and its blend with corn had better crumb softness and lower baking loss (P < 0.05). On the other hand, the regression models for most of the dough rheological and bread textural variables were significant and presented good coefficients of determination (R-2 Adj = 0.60- 0.99) with linear and quadratic fits, thus allowing prediction of the behaviours of these variables for future applications.