Optimization of composite flour biscuits by mixture response surface methodology.

Biscuits were produced from blends of pigeon pea, sorghum and cocoyam flours. The study was carried out using mixture response surface methodology as the optimization technique. Using the simplex centroid design, 10 formulations were obtained. Protein and sensory quality of the biscuits were analyzed. The sensory attributes studied were appearance, taste, texture, crispness and general acceptability, while the protein quality indices were biological value and net protein utilization. The results showed that while the addition of pigeon pea improved the protein quality, its addition resulted in reduced sensory ratings for all the sensory attributes with the exception of appearance. Some of the biscuits had sensory ratings, which were not significantly different (p > 0.05) from biscuits made with wheat. Rat feeding experiments indicated that the biological value and net protein utilization values obtained for most of the biscuits were above minimum recommended values. Optimization suggested biscuits containing 75.30% sorghum, 0% pigeon pea and 24.70% cocoyam flours as the best proportion of these components. This sample received good scores for the sensory attributes.