Study of the evolution of drying-induced flow properties for pulverised cassava grits

Determining the bulk flow properties of pulverised cassava grits is in high demand as designing efficient handling and drying systems remains a bottleneck step in the cassava value chain. A shear tester was used to collect the shear-to-failure data for samples taken at three drying stages. The flow properties were estimated based on the nonlinear Warren-Spring yield loci. The cassava grits' morphology and particle size distribution were also examined by scanning electron microscopy, mechanical sieving, and laser diffraction analysis. Drying reduced the cohesion and tensile strength, respectively, from 1.88 to 0.87 kPa to 0.16 and 0.12 kPa under 4.8 kPa of consolidation normal stress. Based on the flow function index (1/ffc), the very cohesive (0.66 < 1/ffc<0.86) wet sample with 46% wet-based moisture content evolved to cohesive (0.29 < 1/ffc<0.43) at 31% of moisture content. It eventually approached a free-flowing (0.07 < 1/ffc<0.15) state towards the end of the drying process at 14% moisture content.