Rheological and textural properties of gluten-free doughs and breads based on fermented cassava, sweet potato and sorghum mixed flours

Abstract

In this study, the fermented cassava-sweet potato-sorghum mixed flours have been used to produce GF bread using xanthan gum as substitute of gluten. The "constrained mixture design" was used to evaluate the effect of flour proportions on the rheological and textural properties of dough and bread. The pasting properties of flour blends reveal high peak viscosity (750–1076 cP) for blends containing more than 70% cassava flour. Sweet potato and sorghum flours lead to a drop in the peak viscosity in the blend when substituted at 30 and 20% respectively. According to the response surface of the Linear Visco elasticity (LVR G′), 5% of sorghum proportion appears as the critical threshold beyond which the decrease in the proportion of cassava flour makes it possible to increase the solid character of the dough (LVR G′ increases). Analysis of the textural properties (hardness, adhesiveness, elasticity, cohesiveness and chewiness) of the crumb of the fresh and stored breads allowed obtaining an optimal flour formulation made of 75% fermented cassava, 20% sweet potato flour and 5% sorghum. This study demonstrated feasibility of fermented cassava-sweet potato-sorghum mixed flours in GF bread making.