Rheological Characterization of TME 419 Cassava Mash–Water Slurries: Implications for the Design of a Mechanized Fufu Processor

Fufu, a fermented and gelatinized cassava dough, is a dietary staple for hundreds of millions of people across sub-Saharan Africa, yet its production remains overwhelmingly manual because the engineering data required to design processing equipment are largely unavailable. The gelatinization step, in which fermented cassava mash is cooked with water under continuous agitation, is the principal obstacle to mechanization and depends directly on the flow behaviour of the mash–water slurry. This study reports the first systematic rheological characterization of mash–water slurries of TME 419, the dominant improved cassava variety in Nigeria, across a processing-relevant design space. Apparent viscosity was measured with a six-speed rotational viscometer for four cassava mash masses (200, 300, 400 and 500 g) combined with eleven water volumes (300–800 mL), yielding mash-to-water ratios of 0.25–0.67 g mL⁻¹, at ambient temperature (32 °C). All slurries exhibited pronounced pseudoplastic (shear-thinning) behaviour, with apparent viscosity decreasing by a factor of 2.6–2.8 between shear rates corresponding to 100 and 600 rpm and well described by the power-law model. At a fixed water volume of 300 mL, apparent viscosity rose non-linearly from 5.37 Pa·s (200 g) to 19.33 Pa·s (500 g), a 260 % increase, demonstrating an exponential sensitivity of viscous resistance to solid loading. Conversely, for a constant 500 g mash load, increasing the water volume from 300 to 800 mL reduced apparent viscosity by 73.3 %. A mixture density of 1111 kg m⁻³ was determined. The mash to-water ratio is identified as the master design variable, and the data are translated into quantitative guidelines for impeller selection, motor and gearbox sizing, and incremental water management in batch fufu processors, providing a quantitative bridge between artisanal fufu preparation and engineered, reproducible food manufacturing.