Comparison of Cyanide Levels in Selected Cassava Varieties Cultivated in Lurambi Constituency, Kakamega County Using the Picric Acid Method

Abstract

Manihot esculenta Crantz (cassava) is a perennial, woody shrub that has an edible root and is grown in the tropics.Cassava is an important source of calories for millions of people in the tropics.However, all cassava varieties contain cyanide which is among the topmost swiftly working poison.This study was aimed at comparing cyanide levels in three cassava varieties grown by residents of Lurambi constituency, Kakamega County for food.These varieties included Migyera, Serere and MH95/0183.Picric acid method was used in this study to assess the cyanide levels in the cassava tubers.A total of twenty-seven cassava tubers of different ages from three farms were used in this study.The average concentration of cyanide in Migyera was the highest (45 HCN mg/kg) while Serere had the lowest average cyanide concentration (15 HCN mg/kg).Migyera, Serere and MH95/0183 had the highest cyanide level at six months and this cyanide content reduces with increase in age of the tuber, the content of cyanide in Migyera, Serere and MH95/0183 ranged from 15 HCN mg/kg to 30 HCN mg/kg at twelve months, the cyanide levels in Migyera, Serere and MH95/0183 at twelve months were above the limits of cyanide fit for human consumption by WHO (10 HCN mg/kg), cyanide content for Migyera, Serere and MH95/0183 ranged between 10 HCN mg/kg to 30 HCN mg/kg at twelve months forty eight hours after uprooting.Serere had the lowest amount of cyanide post-harvest, 10 HCN mg/kg.It was concluded that Serere was the only variety that contains cyanide content after post-harvest storage that falls within the WHO accepted limit (10 HCN mg/kg).It is recommended that Migyera, Serere and MH95/0183 tubers be harvested after twelve months and stored for at least forty eight hours before consumption.