Balancing functionality and structure in gluten-free bread through germinated glutinous rice flour, corn flour, and rice flour blends

Developing gluten-free bread remains challenging because the absence of gluten often results in poor loaf structure and reduced consumer acceptability. This study investigated the effects of germinated glutinous rice flour (GGRF), corn flour (CF), and high-amylose rice flour (RF) on the physicochemical, bioactive, structural, and sensory properties of gluten-free bread. Response surface methodology (RSM) combined with a simplex-centroid mixture design was used to determine the effects of flour proportions and optimize the formulation. Germination increased the α-amylase activity (18.9 ± 0.50 U/g), total phenolic content (TPC; 135.9 ± 0.36 mg GAE/100 g), γ-oryzanol content (389.2 ± 9.72 mg/100 g), and α-tocopherol content (3.84 ± 0.02 mg/100 g) of glutinous rice flour. However, excessive GGRF incorporation adversely affected bread structure, as the formulation containing 90% GGRF exhibited crumb collapse and the lowest specific volume (1.14 ± 0.01 cm 3 /g). The incorporation of CF and RF improved pasting behavior, crumb structure, and sensory properties. Multi-response optimization identified the blend containing 50% GGRF, 40% CF, and 10% RF as the optimum formulation, with an overall desirability of 0.71. Experimental validation yielded TPC, γ-oryzanol, and α-tocopherol contents of 3.89 ± 0.08 mg GAE/100 g, 21.20 ± 0.19 mg/100 g, and 1.54 ± 0.04 mg/100 g, respectively, and an overall acceptability score of 6.59. These findings demonstrate that blending GGRF with CF and RF can balance bioactive enrichment with technological and sensory quality in gluten-free bread. Further studies should investigate the effects of germination conditions and storage on bioactive stability, bread quality, and shelf life.