Cyanogens in Cassava Flour and Roots and Urinary Thiocyanate Concentration in Mozambique

The total cyanogen content of 90 cassava flour samples from Mujocojo, Terrene A and Acordos de Lusaka in Nampula Province of Mozambique was determined in 1997 using the simple picrate kit method. The results at the first two locations were compared with those obtained at the same locations at the same time of the year in 1996. There was a significant decrease of about 50% in the cyanogen levels at Mujocojo and Terrene A in 1997. Results from Acordos de Lusaka and Mujocojo showed that flour processing by heap fermentation gave a substantially lower cyanogen content compared with sun drying. This confirms the conclusion found in our previous study. The cyanogen levels of flour from Acordos de Lusaka were very high (mean value 67 (39) ppm). The amount of available cyanogen (acetone cyanohydrin +HCN/CN^-) and partially available cyanogen (linamarin) was determined for 37 samples of cassava flour. There was no correlation between the amounts of available cyanogen and partially available cyanogen. Twenty-nine samples of urine from school children at Acordos de Lusaka gave a mean value of thiocyanate content of 512(277) μmolL^-1.