Physical, Chemical, and Bioactive Properties of Bread Made from Particle-Size-Fractionated Wheat Flour.

Bran enrichment improves the nutritional value of wheat-based bread but often impairs appearance, structure and sensory acceptance. This study investigated the role of controlled particle-size fractionation of brown wheat flour (BWF, equivalent to whole wheat flour) into <500 µm and <250 µm fractions in balancing bioactive enhancement and functional potential with acceptable product quality. White wheat flour (WWF) served as a refined control. Bread samples were prepared from WWF, BWF and their two bran-rich fractions, and assessed for appearance, color, physicochemical properties, texture, total phenolic content (TPC), ABTS antioxidant activity, individual phenolics, sensory attributes, correlations and chemometric patterns (using Principal Component Analysis (PCA) and Orthogonal Partial Least Square-Discriminatory Analysis (OPLS-DA)). Flour particle size strongly influenced bread color, texture and crumb structure: BWF bread samples were darkest, firmest and most chewy, whereas <250 µm bread was lighter and softer. TPC and ABTS activity were highest in BWF, followed by <500 µm and <250 µm, mirroring phenolic retention. Specifically, total phenolic content reached 1.58 mg GAE/g and ABTS antioxidant activity 19.49% in BWF, compared with 0.96 mg GAE/g and 18.31% in the <500 µm fraction, and 0.87 mg GAE/g and 17.67% in the <250 µm fraction. Bread hardness decreased from 5437 g in BWF to 4878 g in the <500 µm fraction and 4386 g in the <250 µm fraction. Key phenolic acids, chlorogenic, p-coumaric, sinapic and trans-ferulic acids, showed strong positive correlations with hardness and chewiness and negative correlations with appearance and overall acceptability. PCA and OPLS-DA confirmed distinct biochemical separation among bread types, with the PCA model explaining 73% of the total variance (PC1 = 57% and PC2 = 16%), and phenolic subclass distribution was identified as the main discriminant factor. Bread from the <500 µm fraction preserved phenolics but reduced sensory quality, while finer fractions (<250 µm) improved acceptability at the cost of some flavonoids and antioxidant capacity. Fractionation of flour, therefore, provides a practical strategy to optimize bioactive-sensory trade-offs in fiber-enriched bread samples. This study contributes to efforts in achieving sustainable development goals aimed at improving nutrition and food security.