Cassava and cowpeas are crops of major dietary and economic importance in West Africa. The novel use of cassava flour for baking biscuits is being exploited in Ghana to reduce the huge foreign exchange expenditure on wheat imports. In order to enhance the nutritional quality of the cassava flour, addition of cowpea flour has been proposed. This will also provide another utilization path for cowpeas. Formulation of composite flour from cassava and cowpea that has optimal functionality for baking biscuits was therefore the objective of the study. For formulation, Yebeshie cassava flour has extremely low residual cyanide (<0.06 HCNequiv./Kg) and drum-dried cowpea flour with reduced beany flavor. The central composite rotatable design for K=2 was used to study the combined effect of cassava flour (45%-70%) and cowpea flour (30%-55%) levels on spread factor, hardness, fracturability, and color of biscuits baked from the composite flours. The biscuits were baked using a recipe for cassava biscuits. Fracturability and hardness of the biscuits were measured with a TA.XT2 Texture Analyzer. Preference was evaluated using a consumer sensory panel. Baking qualities that were significantly affected by the addition of cowpea flour were hardness and color of the biscuits. Models developed for these indices gave R2 values of 95.25% for color and 96.83% for hardness of the biscuits. As the cowpea level increased, the degree of browning of the biscuits increased whilst hardness reduced (30.00N for 30% cowpea/70% cassava to 16.39N for 55% cowpea/45% cassava). The composite flour biscuits were preferred over the 100% cassava flour biscuits that were judged to be too hard (42.63N). The 57.5%/42.5% and 48.7%/51.3% cassava/cowpea composite biscuits were most preferred in terms of hardness, fracturability, and color. The addition of cowpea flour enhances not only the nutritional quality but also the sensory quality of cassava biscuits.
- Response surface methodology,
- cassava flour
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