Insights into the physicochemical properties, in vitro digestibility, and consumer acceptance of black rice flour-based bread

This study investigates the physicochemical, nutritional, and sensory properties of gluten-free bread formulated using whole rice flour (WRB), black rice flour (BRB), and their blends at substitution levels of 25% (25-BRB), 50% (50-BRB), and 75% (75-BRB) BRB. Black rice flour exhibited significantly higher concentrations of protein, lipids, minerals, dietary fiber, total polyphenols, flavonoids, and proanthocyanidins compared to WRB. The incorporation of BRB into the bread matrix improved textural parameters, including elasticity, springiness, cohesiveness, chewiness, and resilience, while reducing hardness and adhesiveness. Cyanidin-3-O-glucoside and protocatechuic acid were identified as the predominant polyphenolic compounds in BRB, comprising 83.67% and 63.67% of total polyphenols, respectively, and were not detected in WRB. In vitro starch digestibility analysis revealed a 17.94% reduction ( p < 0.05) in rapidly digestible starch and a 16.00% increase ( p < 0.05) in slowly digestible starch in BRB relative to WRB, contributing to a 5.83% decrease ( p < 0.05) in the estimated glycemic index. Sensory evaluation demonstrated the highest consumer acceptability for bread containing 50% BRB, indicating an optimal balance between enhanced nutritional quality and desirable sensory attributes.