Utilising starchy tropical agri-resources through gluten-free bread-making: the case of cassava, green banana and sweet potato flours

This work evaluated, for the first time, different gluten-free bread formulations using mixtures of cassava, sweet potato and green banana flours. A simplex centroid mixture experimental design with constraints was used to evaluate the role of each flour in the physical properties of dough and bread. Hence, the relationships between the pasting properties of the flours, rheological properties of the doughs and physical properties of the baked breads were investigated. The results showed that increasing the proportion of cassava flour (from 30 to 70 %) enhanced porosity (from 6.36 to 17.89 %) and led to a softer crumb (from 12.48 to 8.07 N); whereas a higher proportion of green banana flour (70 %) resulted in a harder crumb (12.48 N) despite an increase in the bread specific volume (1.33 cm³ g⁻¹). The sweet potato flour input enhanced the staling properties of bread. However, when the input of this flour exceeded the threshold of ∼20 %, the specific volume of the bread (<1.16 cm³ g⁻¹) and its porosity (<11.20 %) and textural properties deteriorated. An optimal formulation containing equal proportions of cassava and green banana flours (43.3 %) and a lower proportion of sweet potato (13.3 %) was identified.