CYANOGENIC POTENTIAL OF CASSAVA FLOUR - FIELD TRIAL IN MOZAMBIQUE OF A SIMPLE KIT

The cyanogenic potential (ppm HCN equivalents) of 80 samples of cassav a flour (obtained from the Mujocojo and Terrene-A areas of Nampula Pro vince and the markets of Nampula City in Mozambique) were determined u sing a new simple kit, based on the use of picric acid paper (Egan et at, 1997). The kit is compact, requires only a small amount of water a nd is very simple to use in the field. Comparison with the results of a semi-quantitative method shows a mean deviation between the two meth ods of 20% (SD 12%). All samples fitted a single population distributi on with a mean value of 45 ppm KCN equivalents (SD 37). Two maxima wer e observed in the distribution curve at 11-20 and 41-50 ppm. Five samp les exceeded 100 ppm with two values of 200 ppm. The WHO safe level fo r cyanogens in cassava flour is 10 ppm. The lowest levels (2 and 6 ppm ) were obtained from cassava flour prepared from sweet cassava. Over 7 6 samples the mean value of the cyanogenic potential of cassava flour produced by heap fermentation is only one half as large as that produc ed by sun-drying (P < 0.005). Interventions needed to reduce cyanogen levels are (1) improvements in processing methods, such as replacement of sun-drying by heap fermentation, (2) introduction of additional ve getables, pulses and fruit to alleviate the monotonous cassava diet of the people and (3) introduction of high-yielding, disease-resistant, low-cyanide cultivars.