Optimized Hydrothermal Pretreatment of Quinoa Seeds and Its Impact on the Functional, Rheological, and Breadmaking...

In this study, hydrothermal treatment conditions for quinoa flour were optimized using response surface methodology, evaluating conditioning time (6-12 h) and drying temperature (50-90°C) against key quality attributes, namely, swelling power and peak viscosity as swelling/expansion indexes, breakdown viscosity as a thermomechanical stability index, and solubility and setback viscosity as retrogradation tendency indexes. The optimal treatment was identified as 12 h conditioning followed by drying at 50°C, with drying temperature exerting the greatest influence on functional properties. The functional characteristics of the optimized hydrothermally treated quinoa flour (OHQF) were subsequently evaluated. Compared with untreated flour, OHQF exhibited increased water absorption capacity (6%), oil absorption capacity (30%), and bulk density (25%), while solubility (33%), peak viscosity (10%), and setback viscosity (4%) were reduced. These changes indicate improved hydration behavior and reduced retrogradation potential. The effects of substituting wheat flour with OHQF at 10%, 20%, and 30% (w/w) on dough rheology and bread quality were assessed, using composite flours containing untreated quinoa flour as controls. At all substitution levels, OHQF increased farinograph water absorption, dough development time, and dough stability and enhanced extensograph dough resistance to extension at 90 min while maintaining improved dough extensibility. Although bread loaf volume decreased with OHQF incorporation, sensory evaluation showed improved acceptability, particularly in crust color and appearance, regardless of substitution level. Overall, 10% substitution with OHQF produced bread with properties most comparable to 100% wheat flour. These findings demonstrate the potential of hydrothermally treated quinoa flour as a functional ingredient and are of direct relevance to the flour milling and baking industries.