Elimination of Cyanique from Cassava Roots Grown in Congo; Case of bitter Variety Ngamanza : Kinetic and Thermodynamic Studies

Kinetic and thermodynamic studies on the elimination of cyanique from cassava roots habe been undertaken using the soaking process. One variety of cassava grown in Congo has been using. The argentometric method was used to monitor and quantify the appearance of cyanide in water. Kinetic constants indicate that (a) potentially toxic concentrations of cyanide are reduce to safer limits in less than three days soaking; and (b) the elimination is faster when fresh sample is used as raw materials at higher temperatures. The values of the equilibrium constants and free energy show that the elimination of cyanique from cassava roots is (a) a spontaneous process and (b) controlled by the entropic factor; in compensation promoting efficiently the fast elimination of cyanide from cassava

Processing of cassava roots to remove cyanogens: short communication

A simple equation is developed between the total cyanide contents of cassava root parenchyma and the processed product with the percentage retention of cyanide on processing. This equation is applied to different methods of processing used worldwide. Thus to produce cassava flour to 10 mg HCN equivalents/kg flour (PPM); the WHO safe level; by sun drying or heap fermentation requires starting with sweet cassava containing 12-32 ppm total cyanide. In an average year only 14 per cent of flour samples in our study areas in Nampula Province of Mozambique had total cyanide contents of 10 ppm. Distribution curves of flour total cyanide show that the percentage of samples exceeding 100 ppm total cyanide increased from 6 per cent in an average year to 43-65 per cent in a low rainfall year; when cases of konzo also occurred. Processing methods used to produce farinha in Brazil and gari in West Africa reduce the total cyanide content to less than one eighth of that using heap fermentation and less than one sixteenth of that using sun drying. Heap fermentation and sun drying; commonly used in eastern and southern Africa; do not adequately remove cyanide in a normal year and are hopeless inadequate when used on cassava grown during drought. New and greatly improved processing methods are urgently needed. The high levels of cyanide intake in central; eastern and southern Africa from high cyanide flour are most likely cause of konzo in young people and the very long term consumption of gari of lower cyanide content in West Africa is the most likely cause of TAN in order people

Epidemiological evidence from Zaire for a dietary etiology of konzo, an upper motor neuron disease

A clear association between seasonal outbreaks of a paralytic disease called konzo and toxic effects from consumption of insufficiently processed bitter cassava roots has been demonstrated in Bandundu region, Zaire. A community-based survey of 6764 inhabitants identified 110 live and 24 dead konzo-affected persons with a history of isolated non-progressive spastic paraparesis of abrupt onset. The start of these annual outbreaks of konzo in 1974 coincided with the completion of a new tarmac road to the capital, which facilitated the transport of cassava and made it the main cash crop. The extensive cassava sales encouraged the consumption by the peasant families of roots that had not been adequately processed; frequent acute cyanide intoxications resulted when the naturally occurring cyanogens in the roots were eaten. The disease mainly appeared in the dry season when there was high consumption of insufficiently processed cassava and the diet lacked supplementary foods with sulfur-containing amino acids which promote cyanide detoxification. These results, which confirm the earlier findings in East Africa, show that, owing to the high cyanide and low sulfur dietary intake, there is an increased risk of konzo outbreaks in cassava-growing areas during periods of adverse agro-economic changes