QUALITY EVALUATION OF HARD DOUGH BISCUIT PRODUCED FROM FERMENTED BAMBARA GROUNDNUT TEMPEH AND WHEAT FLOUR MIXES
There is growing interest in fortifying wheat flour with high lysine material, such as bambara groundnut flour, to improve the essential amino acid balance of baked food products. Bambara groundnut is not adequately utilized in Nigeria. In this study, wheat flour in a standard biscuit formulation was partially or fully substituted with fermented bambara groundnut tempeh flour at six levels: 0%, 5%, 10%, 25%, 40% and 100%. The composite flours were analyzed for physic-chemical properties such as pH, water absorption capacity, bulk density, pasting characteristics and reconstitution index. Biscuit samples were them evaluated for chemical composition, texture, microbial characteristics and sensory properties. Increasing levels of fermented bambara tempeh flour in the mix resulted in changed flour characteristics. Incorporation of fermented bambara tempeh flour exerted positive influence on the nutritional status of the resultant biscuit products based on the level of substitution. Sensory evaluation tests revealed that biscuit sample prepared form wheat flour substituted with 5% fermented bambara groundnut tempeh flour consistently had the highest rating in terms of all the quality attributes assessed. Biscuit that closely followed this was that from pure wheat flour while rating for other samples gradually decreased with increasing level of substitution with bambara groundnut tempeh flour. All the biscuit samples were however acceptable though at varying degrees depending on the level of bambara flour incorporation.