Effect of inulin on rheological, textural, and structural properties of brown wheat flour dough and in vitro digestibility of developed Arabic bread.

Abstract

The brown wheat flour (BWF)-based Arabic bread was fortified with chicory-derived inulin. The objective of this work was to assess the influence of the inulin concentration (1.25 to 5%) on the rheological, textural properties, and fermentation efficacy of enriched BWF dough. Farinographic measurement established that only 3.75% BWF can be substituted by inulin in a dough formulation, which resulted in lowering the water absorption capacity. The peak gelatinization temperature, Tp detected at 74.4 °C by rheometric measurement, which increased linearly with increasing the inulin concentration. The elastic modulus (G'), however, differed significantly among doughs with the addition of inulin. The dough hardness and compressibility increased as a function of inulin concentration. TPA measurement indicated that the Arabic bread fortified with 3.75% inulin was the best in texture. The addition of inulin improved the volume of CO2 generation in the yeasted dough. The distribution of starch particles on the top layer of bread surface was visualized through SEM. In-vitro digestion and steady-flow measurement of the BWF/inulin bread digesta exhibited a slow digestion and an increment in the apparent viscosity against the control bread, which further confirmed potential health benefits of the developed Arabic bread. PRACTICAL APPLICATION: Arabic bread is a staple food in many Asian countries, and an incorporation of soluble fiber, like inulin, definitely improves its health benefits. This work optimized a formulation based on BWF and inulin with technical feasibility. Rheological and textural studies demonstrated that blend bread could be made by replacing 3.75% BWF by inulin with significantly lower water content. Inulin has replaced the sugar in the yeasted dough, and carried out the bread fermentation adequately.