Effect of Selected Pre-Treatments on The Functional and Pasting Properties of Pigeon Pea Flour

Abstract

The effect of three different processing conditions (fermentation, steaming and roasting) on the functional and pasting properties of an under-utilised legume pigeon pea were investigated. This study aimed to optimise these processing conditions for the processing of pigeon peas. Response Surface Methodology (RSM) based on a 3-level full factorial of the Random sample design was selected to optimise the effect of fermentation, steaming and roasting on the quality parameters of pigeon peas. The quality parameters of the pre-treated beans: functional and pasting properties were determined to see the effects of the pre-treatment using standard laboratory procedures. For functional properties, values obtained were: bulk density (0.64 - 0.81)g/ml, water absorption capacity (123.64-174.64)%, oil absorption capacity (78.8-106.13)% , swelling capacity (11.60-27.96)%, foaming capacity 5.57-15.15 and foam stability (0.84 and 6.25)%. Values obtained for pasting properties have their regression coefficient (R2) as peak viscosity, trough viscosity, breakdown viscosity, final viscosity, setback viscosity, peak time and pasting temperature as 0.69, 0.05, 0.51, 0.37, 0.34, 0.07 and 0.54 respectively while the adjusted R2 values for same parameters were 0.39, -0.09, 0.04, -0.25, -0.32, -0.87 and 0.07 respectively. Furthermore, the Coefficient of Variation (CV) derived for peak viscosity, trough viscosity, breakdown viscosity, final viscosity, setback viscosity, peak time and pasting temperature was 8.86, 19.24, 35.03, 4.99, 27.34, 16.57 and 4.29 respectively. The response surface plots depict the effects of steaming temperature and steaming time on the pasting properties of fermented pigeon pea flours. The optimum conditions for the variables investigated with fermented, steamed, and roasted pigeon peas with suitable quality characteristics were fermentation temperature of 270C for 4 days, steaming at 100oC for 20 minutes, and roasting at 1400C for 8 minutes. The pasting properties are also reflective of the functional properties so also the response surface plots. This information will be necessary for the utilisation of pigeon peas with improved physical conditions for exploitation on a large scale.