Evaluation of tigernut (cyperus esculentus l., brown variety) flour in the production of wheat-tigernut composite biscuit

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Tigernut is underutilized crop tuber despite its acclaimed nutrients composition. Biscuits were produced by compositing tigernut flour with wheat flour to explore the effect of tigernut in the product. Brown tigernuts were properly cleaned, dried and milled to obtain the flour. Wheat flour (WF) in the biscuit formulation was replaced at five levels, 10%, 20%, 30%, 40% and 50% with tigernut flour (TF). On a scale of 1 – 9; where 1 = dislike extremely and 9 = like extremely, the sensory attributes (appearance, taste, chewiness, mouthfeel, aroma and aftertaste) of wheat-tigernut biscuits were compared to 100% wheat biscuit (control). Proximate, minerals (Mg, Fe, K, Ca and P), colour and texture were conducted on the most preferred and control biscuit. Generally the biscuits had good consumer preference with the 30% tigernut flour blend being the most preferred with average scale score of 8.02. Incorporation of tigernut flour for the production of 30% wheat-tigernut biscuit resulted in an increase in fibre (1.50-6.20 g), ash (1.04-2.14 g) and (energy 419.90-464.97 kcal) but a decrease in protein content (12.21-9.14 g) as compared to the 100% wheat biscuit. Mineral content (Ca, K and P) for the most preferred formulation increased to (30.01-80.52, 91.50-105.50 and 187.87-198.11 (mg /100 g) as compared to the control biscuit. The tigernut-containing biscuit exhibited dark brown colour as compared to the control biscuit. This can be attributed to the brown colour of tigernut flour in the blend. Measurement of baked biscuits texture showed that hardness and fracturability values decreased as tigernut flour content in the biscuit formulation increased. Differences in hardness and fracturability of the biscuits due to various levels of tigernut flour incorporation might be as a result of differences in protein and carbohydrate contents of the products. Wheat flour contains high amount of gluten and starch which may have contributed to the firmness of the control biscuit as compared to the tigernut flour substituted biscuits since the tigernut flour contains no gluten but high in fibre which may have interfered with the texture of wheat-tigernut biscuits. The Promotion and adoption of wheat-tigernut based biscuits would increase the tigernuts nut utilisation and may drive the chain of production of the tigernuts.
A thesis submitted to the Department Of Food Science And Technology, in partial fulfilment for the award of the degree OF (Master of Science in Food Science and Technology), 2015
Tigernut flour, Biscuits, Sensory evaluation, Parameters, Colour and Texture analysis