Effect of zucchini powder incorporation on the dough rheology and physico-chemical, sensory and quality of Taftoon bread

Since the dietary fiber has an important role in human nutrition, Incorporation of fibers into bread can compensate for its shortcomings and change it into functional food. Dietary fibers enhance the nutritional value of bread; however, they change the rheological properties of the dough, thus altering the final product quality. The objective of the present study was to investigate the effect of the addition of zucchini powder in different levels of 5%, 10% and 15% to flour, on the rheological properties of the dough as well as physicochemical and sensory properties of bread. In this study, zucchini slices were dried in a hot-air dryer until reaching 9% moisture content. The zucchini powder was prepared and added to wheat flour in different amounts. Rheological properties were measured for each treatment using a Farinograph instrument. The extensibility and tensile strength of the dough in addition to the bread texture were evaluated using a texture analyzer to investigate the bread staling during 72 h. The color of bread was evaluated by measuring L*, a*, and b* Hunter lab color parameters. The 5-point hedonic scale was used to assess the quality of the bread samples. By increasing the zucchini powder percentage, the amount of ash and fiber increased. As the zucchini powder content increased, the water content absorption slightly decreased, however, the stability and quality index of the dough increased. The zucchini powder caused an increase in the dough extensibility and tensile strength. The redness (a* parameter) of bread which was fortified with zucchini powder decreased with increasing zucchini powder. Treated bread texture was softer than the control while the staling rate increased. Sensory evaluation showed that bread containing zucchini powder has higher overall acceptance than the control sample.