Functional and Rheological Properties of Gluten-Free Flour Blends from Brown Eragrostis tef (Zucc.) Trotter and Glycine max (L.) Merr

The increasing prevalence of celiac disease and demand for nutritious gluten-free alternatives have driven interest in cereal-legume composite flours. This study examined the functional, rheological, and textural properties of gluten-free flour blends formulated from brown (red) teff (<i>Eragrostis tef</i> (Zucc.) Trotter) and soybean (<i>Glycine max</i> (L.) Merr.) at different ratios (100:0, 90:10, 80:20, 70:30, 60:40, 0:100). Absorptive characteristics, particle size distribution, pasting behaviour, viscoelastic properties through oscillatory rheology, and texture profile analysis were evaluated. Soybean flour exhibited higher water holding capacity (5.54 g/g) and water solubility index (40.18%), while teff demonstrated notable water absorption index (5.62 g/g) and swelling power (6.18 g/g). Particle size analysis revealed that coarse fractions enhanced water binding and solubility, whereas fine fractions favoured hydration and swelling. Pasting properties showed that teff achieved a peak viscosity of 12,198 mPas in water, significantly reduced to 1839 mPas with AgNO₃. Pure teff exhibited the highest storage modulus (1947.98 Pa) and hardness (7.60 N), whereas the incorporation of soybeans progressively softened the texture. The complementary functional properties of teff and soybean demonstrate promising potential for developing nutritionally enhanced, protein-enriched gluten-free products, with solvent selection and blending ratios serving as critical optimization parameters for specific food applications.