Functional Properties of Tigernut and Cowpea Flour Blends

The pH and functional properties: water and oil absorption capacity, bulk density, solubility, swelling power and foaming capacity of tigernut and cowpea flour blends were determined. The flour blends were coded with the letters B, C, D, E, F, G and H for cowpea flour substitutions of 5, 10, 15, 20, 30, 40 and 50 % respectively. For comparison sample A1, A2 and A3 representing 100 % of wheat, tigernut and cowpea respectively, were also evaluated. Standard methods were used for all the analysis. pH of the flour samples varied significantly (P ≤ 0.05) from 5.60-6.23 for sample B (5 % cowpea flour substitution) and A2 (100% tiger nut flour) respectively. Water and oil absorption capacity varied significantly (P ≤ 0.05) from 1.00-2.90 ml/g and 0.39-1.38 ml/g respectively. Sample A1 (100% wheat flour) and Sample B (5% Cowpea: 95% tigernut flour) was significantly (P ≤ 0.05) the highest in water absorption capacity while sample A1 (% wheat flour) had the highest oil absorption capacity. Bulk density varied from 0.58 - 0.84 g/cm3. Although Cowpea flour (sample A3) had the highest bulk density, there was significant (P ≤ 0.05) decrease with increase in cowpea substitution. Swelling power and solubility ranged from 0.08-6.74 g/g and 8.00–67.35 % respectively. Sample A1 (% wheat flour) had significantly (P ≤ 0.05) the highest solubility and swelling power while Sample A3 (% cowpea flour) had the least. The functional properties of the tigernut-cowpea composite flour were comparable with that of the wheat flour, except for the swelling power that was significantly (P ≤ 0.05) higher for the wheat flour. The result showed that the composite tigernut-cowpea flour can be good alternative in the production of bakery products that would not require much swelling.