Determination of Cyanide Concentration Levels in Different Cassava Varieties in Selected Iodine Deficiency Disordered (IDD) Areas of Wolaita Zone, Southern Ethiopia

Abstract

Cassava (Manihot esculenta Crantz) is a cyanogenic plant which is toxic when consumed without sufficient processing. Cassava is characterized by presence of linamarin a cyanogenic glycoside and when acted upon by an enzyme linamarase is hydrolysed into cyanohydrin which is further hydrolyzed to give hydrogen cyanide (HCN) which is toxic. This study aimed at determination of the levels of cyanide in the sweet cassava variety grown in different geographical regions of Wolaita zone namely Offa, Kindo koysha and Kindo didaye woredas.

The picrate paper method and UV-Visible Spectrophotometric Determination Procedure were used. The study also reports on variation of cyanide concentration within varieties and its concentration in different parts of cassava root. The concentration of cyanide varied significantly (p<0.05), with the geographical location. The concentration of cyanide in cassava from Kindo koysha was highest (66±3.5 mg/kg), while cassava from Kindo didaye had the lowest cyanide concentration (29.35± 3.7 mg/kg), While the cyanide concentration in cassava from Offa was 47.725± 4.21 mg/kg. Three parts of cassava root (Pith,Cortex and Parechyma) contained significantly different concentrations of cyanide; 49.24±3.12, 81.23±2.84, 68.45±2.2mg/kg respectively. The concentrations of cyanide in cassava from all the study sites were higher than the recommended level by WHO (10mg of HCN/kg body weight). The median urinary iodine concentration (38.27μg/L) was also found in study site confirms that the area is moderately affected by iodine deficiency. This study provides critical information on the potential toxicity of cyanide in cassava from the three woredas of Wolaita zone.

Keywords: cassava; cyanide; picrate method; Kello; Qulle