Open Agriculture. 2016; 1: 173–178 parameters evaluated however bread from higher levels of substitution varied significantly with the control. All the bread samples were acceptable in all the parameters evaluated except bread from 20% level of substitution. The study concludes the potential health and sensory benefits of partial substitution of sweet potato and tiger nut to wheat flour in bread making through improved fibre content, improved taste and to promote sweet potato and tiger nut utilization. Keywords: sweet potato, tiger nut, bread, composite flour, substitution 1 Introduction Bread, a staple food in developing countries is consumed in large quantities because it is affordable, is an excellent source of nutrients and is available in a “ready to eat” form (Darko, 2002). Wheat, the basic ingredient in bread making is one of the most important crops grown round the world, however it cannot be grown in all bread consuming areas hence it may need to be imported making it relatively expensive according to the reports of Edema et al. (2005) and Olaoye et al. (2006). Before now, imported wheat flour has been the only kind of flour used in bread production in Nigeria. However, over the years, in response to the increase in the price of wheat, reports have been published on successful composite bread technology (though such bread still requires at least 70% wheat flour to be able to rise) if substituting with indigenous crops like soybeans, plantain, cocoyam, sweet potato, breadfruit etc (Oluwole et al., 2005; Onuh and Egwujeh, 2005; Olaoye et al. 2006; Eddy et al., 2007; Ade-Omowaye et al., 2008; Malomo, 2010; Malomo et al., 2011). Utilization of these composite flours would reduce the demand for imported wheat; conserve foreign reserves (Eddy et al., 2007) and widen the utilization of indigenous crops in food formulation (Ade- Omowaye et al., 2008). DOI 10.1515/opag-2016-0022 Received November 8, 2016; accepted December 20, 2016 Abstract: The study was carried out to assess the nutritional quality and palatability of bread after partially substituting wheat flour (WF) with sweet potato (SF) and tiger nut (TF) flours. Sweet potato (yellow fleshed) and tiger nut flours were used to substitute wheat flour at 5, 10, 15 and 20% level each. The bread quality of each of these composite flours evaluated on the basis of their nutritional quality, physical properties and acceptability by consumers. The findings indicate slight decrease in the protein content of the bread samples with increasing sweet potato and tiger nut supplementation (6.97% in 100% wheat flour to 3.80% in 20% level of substitution) while crude fibre content increased with increased sweet potato and tiger nut substitution (2.29% in 100% WF to 2.80% in 20% substitution) but there was no significant change (P<0.05) in the ash and fat contents. Carbohydrate which was the major component ranged from 73.47 – 79.42%. Findings on the study on the functional properties showed that water absorption capacity increases with increase in the level of sweet potato and tiger nut substitution (0.54g/ml in 100% WF to 1.12g/ml in 20% level of substitution). The loaf volume and specific volume of the bread samples decreased significantly with increase in the level of substitution with sweet potato and tiger nut and it ranged from 320cm 3 (in 100% wheat flour) – 216cm 3 (in 20% substitution) and 1.55cm 3 /g (in 100% wheat flour) to 0.98cm 3 /g (in 20% level of substitution) respectively. Bread from 100% wheat flour scored the highest in all the sensory properties evaluated. There was no significant difference between the control and bread from 5% level of substitution in terms of all the sensory Research Article Open Access © 2016 Chinelo V. Ezeocha, Nnenna A. Onwuneme, published by De Gruyter Open. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License. Chinelo V. Ezeocha*, Nnenna A. Onwuneme Evaluation of suitability of substituting wheat flour with sweet potato and tiger nut flours in bread making *Corresponding author: Chinelo V. Ezeocha, Michael Okpara University of Agriculture, Umudike, Nigeria, E-mail: vanessa. ezeocha@gmail.com Nnenna A. Onwuneme, National Root Crops Research Institute, Umudike, Nigeria