Rheological behaviour, physical and sensory properties of orange fleshed sweet potato and soy concentrate bread.

Trends on the use of non-wheat flours for bread production has led to researches on improving the rheological characteristics of such non-wheat flours. This aim of this study was to determine the effect of soy concentrate on the protein and rheological behaviour (pasting and mixolab) of the orange-fleshed sweet potato composite flour as well as the physical and sensory qualities of the bread produced. The experimental design to obtain the optimum blends was carried out using optimum design of response surface methodology; with sweat potato, soy bean concentrate, date palm flour and potato starch as the independent variables. The result shows that protein values ranged from 6.19 to 21.10%, carotenoid values ranged from 0.11 to 26.18 mg/100 g. pasting temperature ranged from 68.50 to 82.33 °C; peak viscosity ranged between 159 and 1040 RVU, the breakdown value ranged between 24 and 272 RVU and the setback value ranged from 75 to 368 RVU. The bread loaf weights ranged from 111 to 256 g and the specific loaf volume ranged from 0.7 to 1.6cm3/g. The bread samples varied significantly (p < 0.05)  with the consumer's acceptability in terms of aroma, appearance, taste and overall acceptability. It was observed that soy-concentrate increase the protein content and improves rheological properties of the composite flour for the production of gluten free bread.