## Materials and Methods  
### Experimental Procedure  
The study was performed as a survey of the current practices of a small-size cassava processing enterprise located at the town of Abura Dunkwa in the Central Region of south Ghana (5\({}^{\circ}\)19\({}^{\prime}\)58\({}^{\prime}\) north; 1\({}^{\circ}\)10\({}^{\prime}\)13\({}^{\prime}\) west). This cassava processing enterprise grows its cassava but also buys it from other growers in the region. The survey followed the usual material preparation and drying procedure of the cassava processing enterprise, and no interventions were made other than collecting samples and measuring drying conditions. This enterprise uses a fixed-bed dryer and a pneumatic dryer to produce cassava flour. The final product is shipped in bulk to Accra and sold to wholesalers, who evaluate the flour appearance and moisture content to assess quality. The survey used a comparative experimental design, with 5 replicates. Each dryer type was considered as a treatment and data collection was conducted over 10 consecutive days, in series, one dryer type per day. The order in which each dryer was used was randomized. The steps used to process the cassava root into flour are shown in Figure 1. At the processing enterprise locally grown, freshly harvested, cassava roots were peeled by hand, washed manually and turned into a mash using a mechanical grater. The mash was subsequently dewatered with a screw operated press and then the resulting press-cake was pulverized into wet cassava grids using another mechanical grater. When the fixed-bed dryer was used, the equipment was loaded with 500 kg of wet cassava grits without preheating. The wet grits were spread over the perforated screen forming a 0.15 m thick layer. Aiming to improve uniformity, after 3 h of drying, the operator manually turned and shifted the cassava grits with a wooden shovel. Drying lasted for a total of 6 h. During the drying process, the temperature of the drying air was thermostatically controlled using a temperature sensor located at the dryer inlet. The thermostat was set to 90 \({}^{\circ}\)C and kept at this value. When the pneumatic dryer was used, it was preheated for 0.5 h before being loaded with wet cassava grits. Once loading started, it continued uninterrupted for 7.5 h. In this period, a total of approximately 500 kg of wet cassava grits were fed to the dryer. Drying air temperature was thermostatically controlled using a temperature sensor located at the dryer inlet, placed before the feeding point. The thermostat was set to 220 \({}^{\circ}\)C and kept at this value. The fixed-bed dryer was locally manufactured, built in a rectangular shape, 2.54 m by 2.45 m with a height of 0.85 m, as illustrated in Figure 2a. The perforated screen was located approximately in the middle of its height and was inclined by an angle of 8\({}^{\circ}\) to facilitate unloading. The equipment was constructed using stainless steel and was thermally insulated with a 50 mm thick mineral wool, shielded by aluminium sheeting. Air was heated by a heating unit comprising a 70-kW diesel burner and a heat exchanger. Airflow was forced by a radial blower powered by a 5.2 kW three-phase electric motor. The pneumatic dryer was also locally manufactured. However, as part of a capacity-building activity of a rural development project, in which equipment manufacturers in Ghana learned how to design, dimension and build small-scale pneumatic dryers for cassava processing. The equipment was constructed using stainless steel and was thermally insulated with a 50 mm thick mineral wool, shielded with aluminium sheeting. The drying duct had a diameter of 0.18 m and a length of 24.84 m. To reduce the total height of the equipment the drying duct was divided into 7 vertical meandering sections, as illustrated in Figure 2b. Wet cassava grits were introduced to the drying duct by a feeder powered by a 4.0 kW three-phase electric geared motor. Airflow was forced by a radial blower powered by a 7.5 kW three-phase electric motor.