Some Quality Attributes of Composite Flour and Bread Produced from Wheat and African Walnut

This study explored the potential of African walnut in the formulation of composite flour which can be used for bread production and in various food applications. African walnut flour was produced and used to substitute wheat flour at different levels (5 - 25%) in the production of wheat-African walnut composite flour. Functional and pasting properties of the composite flour were evaluated using standard procedures. Proximate composition, antioxidant activity, some loaf quality attributes and sensory acceptability of bread produced from the composite flour were evaluated using standard procedures. Wheat bread served as control. The composite flour showed varying functional properties which ranged from 2.43 to 3.46 (swelling capacity), 1.15 to 1.85 mL/g (water absorption capacity), 2.15 to 2.75 mL/g (oil absorption capacity), 10.80 to16.60% (foam capacity), 63.0 to 75.0% (dispersibility), 38.92 to 69.92 seconds (wetability), 0.75 to 0.79 g/mL (packed bulk density) and 0.43 to 0.47 g/mL (loose bulk density). Inclusion of African walnut reduced peak viscosity (53.92 – 148.83 RVU), trough viscosity (52.25 – 88.58 RVU), breakdown viscosity (1.67 – 60.25 RVU), final viscosity (74.08 – 191.25 RVU) and setback viscosity (21.83 – 102.67 RVU) of the composite flour. Composite bread had better protein (9.75 – 16.93%), fat (3.42 – 9.94%), ash (1.46 – 2.75%), crude fibre (0.86 – 3.64%) but reduced specific loaf volume (2.36 – 4.18 cm3/g) and loaf height (3.00 – 5.40cm) than the control, and exhibited appreciable antioxidant activity (DPPH: 31.60 – 73.09% and FRAP: 0.51 - 4.25 mg/g). In term of sensory acceptability composite bread samples produced with 5 and 10 % levels of African walnut compared favourably with bread produced from wheat flour. Thus composite flour produced from wheat and African walnut flours showed an array of physicochemical properties which could make it useful in different food applications. Acceptable bread could be produced from wheat flour substituted with African walnut flour at 10% level.