Effect of partial replacement of wheat with peanut flour on the chemical, sensory and microbial quality of bread

Background: Consumption of bread is continually growing despite the high cost of wheat importation. There is a dire need to reduce the dependence on wheat through partial replacement of wheat with indigenous crops as well as improving the nutritional value of carbohydrate based foods.Objectives: The objectives of this study were to assess the chemical, sensory and microbiological qualities of bread fortified with peanut flour.Materials and Methods: Four samples of bread were formulated by blending wheat flour with partially defatted peanut flour at various ratios of 100:0, 90:10, 80:20 and 70:30 (Wheat: Peanut). The 100:0 ratio (Wheat: Peanut) served as control. The proximate composition, pro-vitamin A, sensory properties and the microbiological qualities were evaluated using standard methods of analysis. The data obtained were subjected to statistical analysis.Results: The Proximate composition result showed that ash, fibre, fat and protein contents increased as the proportion of peanut flour increased in the blend  formulation from 0.50% to 1.35%, 0.48% to 2.84%, 4.40% to 12.70% and  9.019% to 18.16% respectively. Carbohydrate content decreased with increase in the proportion of peanut flour from 53.37% to 36.10%. Pro-vitamin A content increased in a dose dependent manner (0.49mg/100g to 12.20mg/100g). Sensoryevaluation results indicated that all the bread had high sensory ratings for all the parameters evaluated. The total viable count of the bread samples during ten days of storage ranged from 1.80x102 cfu/g to 4.8x105 cfu/g. Fungal count ranged from 1.2x102 cfu/g to 5.0x103 cfu/g. Some species of fungi and bacteria were isolated after ten days of  storage.Conclusion: Substitution of wheat flour with peanut flour up to 30% produced a more nutritionally adequate,organoleptically acceptable and microbiologically shelf stable bread.Keywords: Bread, Peanut, Fortification, Microbial Quality