Nutritional, Physical, and Sensory Evaluation of Wheat Flour Biscuits Supplemented with Bambara Groundnut and Bush Mango Flours

Abstract

This study was designed to evaluate the nutrient composition, microbiological, physical and sensory properties of biscuits produced from blends of wheat, Bambara groundnut and bush mango mesocarp flour. Bambara groundnuts and bush mango mesocarps were separately processed into flours. Each of the flours was used at varying replacement levels (5-30%) to complement wheat flour in the production of biscuits, with biscuits produced from 100% wheat flour as control. The nutrient composition, microbiological, physical and sensory properties of the biscuits were determined using standard methods. The moisture, crude protein, fat, crude fibre and ash contents of the biscuits increased significantly (p<0.05) with increased substitution of Bambara groundnut and bush mango mesocarp flours from 6.42-7.65%, 7.32-17.32%, 3.25-4.24%, 3.32-5.03% and 1.42-2.11, respectively with subsequent decrease in carbohydrate and energy contents. The mineral composition of the biscuits also increased significantly (p<0.05) with increase in the addition of Bambara groundnut and bush mango mesocarp flours from 77.86-133.27 mg/100g calcium, 95.47-167.72 mg/100g potassium, 89.11-147.26 mg/100g phosphorus, 57.54-116.04 mg/100g magnesium, 1.64-2.04 mg/100g iron and 1.43-1.91 mg/100g zinc. The niacin,  thiamine, riboflavin, vitamin A, ascorbic acid, and folic acid contents of the samples also ranged from 2.54-3.26 mg/100g, 2.57-3.47 mg/100g, 2.61-3.26 mg/100g, 3.23-4.36 mg/100g, 1.43-1.91 mg/100g and 1.12-1.71 mg/100g, respectively. The result showed that the vitamin contents of the composite biscuits increased gradually with increased substitution of Bambara groundnut and bush mango mesocarp flours. The microbial counts of the biscuit samples showed that the total viable count of the samples ranged from 0.32 x 104-1.20 x 104cfu/g, while the coliform and fungal counts were nil which is an indication that the products would be safe, wholesome and shelf-stable with adequate packaging and storage. The height, weight and thickness of the biscuit samples also showed significant (p<0.05) increase with increased substitution of Bambara groundnut and bush mango mesocarp flours, while the diameter, spread ratio and spread factor decreased. The sensory properties of the samples showed that the biscuits made from 100% wheat flour (Control) were most preferable to the panellists and also differed significantly (p<0.05) in colour, mouthfeel, flavour and crispiness.  In addition, the biscuits prepared from the composite flours were also acceptable because they were equally rated high by the judges in all the sensory attributes evaluated. The study, therefore, showed that the nutrient contents and some physical properties of wheat flour biscuits could be improved by the addition of Bambara groundnut and bush mango mesocarp flours at different stated levels in the preparation of biscuits.