Optimization of functional wheat-based bread formulation using mixture response surface methodology

Bread is a commonly consumed staple and its formulation with functional ingredients such as dietary fiber and phenolic antioxidants could enhance its antioxidant potentials. Functional bread was formulated from composite flours of wheat (WHF), malted millet (MMF) and okara (SYF). The study was carried out using mixture design approach as an optimization technique. A simplex-centroid mixture design was used to generate fourteen (14) experimental runs based on different combinations of wheat (70-90%), malted millet (5-45%) and okara (5-45%) flours. The composite flours were processed into bread and analyzed for sensory qualities and antioxidant properties (radical scavenging activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), total flavonoid (TFC) and total phenolic (TPC) contents. Contour plots were used to relate responses, i.e. appearance, crust color, taste, texture, and overall acceptability of bread, as well as antioxidant properties of the developed bread from different proportions of the flours. Results showed that the optimum flour combination that produced higher antioxidant properties and acceptability was 65.18% WHF, 19.43% MMF, and 15.39% SYF with a desirability function of 0.61. Wheat flour significantly (p≤0.05) influenced the sensory characteristics while the increased proportion of malted millet and okara flour significantly (p≤0.05) increased the total antioxidant properties of the bread. This study showed the potential of wheat, malted millet, and okara flour blends in the development of functional bread with acceptable sensorial qualities, and enhanced antioxidant properties.