Fresh cassava roots are highly perishable and contain 65–70 per cent moisture (water), whereas high-quality cassava flour (HQCF) contains only 10–12 per cent moisture and has a much longer shelf life. Reduction of moisture is a key step in processing cassava roots into HQCF and must be done quickly to avoid lowering product quality.
Preparation for sun drying
Efficient removal of moisture requires airflow and heat energy, which can be provided by the sun or artificially by burning oil to generate hot air. Artificial drying is expensive and sun drying depends on availability of sunlight.
For these reasons, it makes good sense to remove as much water as possible from the product before drying. This is achieved by pressing the grated cassava mash in a jack press for a period of approximately two hours.
Sun drying offers the simplest way to dry pressed cassava cake and is best suited for small-scale rural operations where product volumes are low (50–100kg of dry product per day). Efficient sun drying requires a combination of sunlight, dry air (low humidity) and good airflow over the product. Simple approaches to sun drying involve spreading the wet product on a concrete drying floor or a black plastic sheet laid on top of a concrete drying floor.
Construction of improved sun-drying racks
A much better approach is to spread the product on special drying racks that have a porous drying surface to improve airflow. The drying surface for these racks is made from mosquito mesh stretched over a rectangular wooden frame 2m-long by 1m wide (see Figure 1). The main frame is made from timber (8cm x 2cm section is sufficient) of sufficient strength to maintain shape when wet product is loaded on to the mesh. The four parts of the frame are screwed together to make maintenance easier.
Please read the leaflet below for more information