Effects of Processing Techniques on the Level of Cyanogenic Glycosides and Hydrogen Cyanides in Cassava Flour

Abstract

This work investigated the toxicity level of Cyanogenic glycosides, hydrogen cyanide in palm oil, fermented and unfermented cassava flour. The cassava flour processed by different methods was made to undergo qualitative and quantitative using Zhou S., method of analysis. Results show that the three cassava flour samples (dry fermented garri, oil garri and water submerged fermented garri) contain 0.986mg/kg, 0.864mg/kg and 0.986mg/kg Cyanogenic glycoside, hydrogen Cyanide (0.0049 mg/kg, 0.0043mg/kg and 0.0049mg/kg ) respectively. Both compounds concentration are reduced in oil garri. This is attributed to the glycosides and non glycosides undergoing hydrolysis, which is in line with Cooke who said that microorganisms are not necessarily involved in the breakdown of Cyanogenic glycosides. This study clearly shows that addition of palm oil to garri helps in delaying the decomposition of Cyanogenic glycosides while it also reduces the formulation of hydrogen cyanides. The three methods of preparation yields are below the tolerable level of acute reference dose (ARFD) of 0.09mg/kg bw (body weight) and provisional maximum tolerable daily intake (PMTDI) of 20mg/kg bw/d as recommend by World Health Organization. Fermentation by submerging cassava in water for days before frying, contain higher amount of Cyanogenic glycoside which releases higher concentration of hydrogen cyanide due to hydrolysis. Cassava flour made of palm oil (yellow garri) is highly recommended for those without diabetic issue since it contains some amount of vitamin A, E and K from palm oil and lesser amount of HCN which made it less toxic.