Rheological study of cowpea puree ‘adowè’ and the influence of saliva on the puree viscosity

The traditional preparation of adowè is laborious, time, water, and fuel consuming and this has resulted in a decline in its consumption. We investigated the characteristics of adowè where powder-based products were used to formulate the traditional puree as a means of reducing the cost of the dish. In the absence of additional salt, the cooking of cowpea seeds was characterised by two activation energy domains from the swelling kinetics below and above 60 °C ± 5 °C of ≈15.30 and ≈28.35 kJ mol⁻¹, respectively. Decorticated seeds were completely cooked after ≈60 min at 95 °C and the puree of 31% ± 2% (w/w) exhibited an apparent viscosity of ≈6 kPa s at ≈0.1 s⁻¹ and 23 °C, as determined by the back extrusion method. The purees exhibited a shear-thinning flow, time decreasing viscosity at constant shear rate, and a partially recoverable capacity. At a shear rate of 50 s⁻¹ and for a shearing time of 80 s, the viscosity increased sharply by a factor 200 as the concentration was increased from 12% to 20% (w/w) by a factor 1.67. In the presence of saliva, the viscosity was shown to remarkably decline with a greater impact for concentrations ≈15% (w/w).