Soaking and drying of cassava roots reduced cyanogenic potential of three cassava varieties at Jimma, Southwest Ethiopia
Detoxification of three cassava varieties (NR-44/72, NW-45/72 and NW-44/72) by traditional methods of processing to produce cassava flour was investigated at the college of agriculture, Jimma University during February to May, 2007. The total hydrogen cyanide (HCN) quantitative determination in cassava flour was carried out using a simple enzymatic picrate paper method. Results show that varieties, soaking time and their interactions highly significantly reduced (P<0.01) total HCN content (ppm) in the flour. Soaking of cassava chips in water for about 24 h prior to sun drying reduced the HCN from 108.37 to 10.83 ppm (reduced by 90%), from 66.45 to 13.33 ppm (reduced by 79.94%) and from 58.63 to 15.0 (reduced by 74.42%) for varieties NW-44/72, NR-44/72 and NW-45/72, respectively. It was noted that total HCN content in cassava flour can be substantially eliminated (by more than 80%) by soaking of cassava chips in water. This study highlighted the importance of soaking of cassava chips for at least 24 h prior to sun drying for a safe level of HCN in the flour. However, it is also important to develop new and improved processing techniques to reduce HCN substantially.
Key words: Cassava flour, soaking, total hydrogen cyanide.