Evaluation of suitability of substituting wheat flour with sweet potato and tiger nut flours in bread making

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 (<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 320cm3 (in 100% wheat flour) – 216cm3 (in 20% substitution) and 1.55cm3/g (in 100% wheat flour) to 0.98cm3/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 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.

Influence of Partially Substituting Wheat Flour with Tiger Nut Flour on the Physical Properties, Sensory Quality, and Consumer Acceptance of Tea, Sugar, and Butter Bread

“…Flour, nutmeg, and margarine were separately weighed and hand-mixed to obtain evenly mixed ingredients. After adding the yeast solution to the flour, the mixture was rubbed together to obtain a rough dough followed by kneading using a rolling machine to obtain a fine-textured dough [ 13 ]. Based on the recipe in Table 1 , WF substitutions resulted in B b and S b with TNF compositions of 7.7%, 11.6%, 15.4%, 19.3%, and 23.2% and for T b , 8.5%, 12.7%, 17.0%, 21.2%, and 25.4%.…”

“…For each type of bread, 1000 g dough was sliced, rolled, molded, and arranged in a baking pan and covered with a clean cloth in an enclosed room to allow for proofing at ambient temperature (28-32°C) for 60 min. Then, the dough was transferred to a Swiss baking oven maintained at 230°C for 30 min [ 13 ]. The baked bread was transferred to a cooling room to equilibrate at room temperature and packed in translucent polythene bags until analyses.…”

“…The specific volume of bread was determined by measuring the weight and the volume by the displacement method according to the procedure by Ahemen et al [ 11 ] with a few modifications: after displacement, the volume of the residual millet grains was measured by transferring into a graduated cylinder and recorded in cm 3 [ 13 ]. Specific volume was computed according to Dabels et al [ 18 ] using equation ( 3 ) as follows: where v (cm 3 ) is the volume and w (g) is the weight of the bread.…”

“…Indeed, the incorporation of tiger nut in the formulation of bread, which is a universal ready-to-eat worldwide staple [ 11 ], has received additional attention because of the simplicity of the production process and ingredient availability and flexibility of incorporating different flour types [ 12 ]. The use of tiger nut in bread baking can lead to possibilities for creating healthier products with enhanced minerals and fiber [ 6 ] whilst serving as an avenue for utilizing the underexplored, less known, nutrient-rich tuberous rhizome for food [ 13 ].…”

“…A few reported studies showed that partially substituting wheat flour with tiger flour by more than 8% significantly reduced bread-specific volume, crumb moisture, and dough extensibility, resulting in decreased consumer acceptance [ 14 ]. Others showed that partial substitution of wheat flour bread allowed up to 15% tiger nut flour without detracting significantly from the sensory properties [ 13 ]. Whilst the method of preparation is likely to influence the use of tiger nut flour in bread making, the type of bread under consideration could influence the allowable levels of flour substitution and consumer acceptability.…”