Changes in the viscosity and energy density of weaning maize porridge on supplementation with groundnut paste and dairy milk

Abstract

The effect of replacing 25% of the basic maize flour with groundnut paste (w/w) and/or 10% of the liquid ingredients with fresh dairy milk (v/v) on the viscosity and energy density of weaning maize porridge was investigated in a 2• fractional factorial experiment. Other factors investigated included (i) particle size of the flour (ii) concentration of the porridge (iii) cooking time (iv) the temperature of the porridge at the time of viscosity measurement and (v) the shear speed and shear time of the viscometer during viscosity measurements. The viscosity of the porridge was measured using 1 rotational viscometer while its energy density was determined by calculation from the proximate values of the raw ingredients. The results showed a significant reduction in the viscosity of the maize porridges due to addition of groundnut paste (P<0.001) or fresh dairy milk (P<0.001). Overall, ground nut alone decreased the viscosity of the porridges by 56. 1%, milk alone by 26.0% and groundnut plus milk by 64.9%. The influence of the addition of groundnut on the viscosity of the porridges was significantly influenced by concentration of the porridge (P<0.001), shear speed (P<0.01), cooking time (P<0.025) and flour particle size (P<0.05) with groundnut reducing the viscosity more at higher concentrations, lower shear speeds, higher cooking times and with fine particle-sized flour. The influence of addition of dairy milk on the viscosity of the porridges was significantly influenced by concentration (P<0.001) and flour particle size {P<0.05) with milk reducing the viscosity more at higher concentrations and with fine particle-sized flour. The energy density of the porridges was substantially increased by addition of groundnut alone (11.5%), milk alone (25.0%) and groundnut plus milk (36.4%). These results indicate that the viscosity of weaning maize porridges can be reduced and the energy density increased by supplementation with groundnut paste and/or dairy milk. As energy deficit has been found to be the most significant factor in the aetiology of protein-energy malnutrition (PEM), it is therefore recommended that weaning cereal porridges should be supplemented with energy-rich foods.