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Current methods for processing cassava leaves to remove cyanogens involve pounding followed by boiling in water or boiling intact leaves for 30 min or longer. Boiling in water rapidly removes cyanogens but also breaks down vitamins, proteins and S-containing amino acids, which are necessary to detoxify ingested cyanide. Two methods have been developed to remove cyanogens whilst conserving these key nutrients present in cassava leaves. The first method involves pounding leaves in a pestle and mortar for a minimum of 10 min until the leaves are well macerated, followed by washing the pounded leaves twice in twice their weight of water at ambient temperature, which reduces the total cyanide remaining to 8%. Two further washes reduce the total cyanide to 3%. The second method is to immerse cassava leaves in ten times their weight of water at 50 ± 3 °C for 2 h followed by one change of water and further immersion for 2 h at 50 °C which reduces the total cyanide remaining to 7%.

The lactic acid content of gari, was determined by pH titration to be about 10 g lactic acid/kg gari. As the size of the gari particles increased from 400 to >1000 μm their total cyanide content increased from 5 to 21 ppm. The acetone cyanohydrin content of gari samples exposed to ambient laboratory conditions of temperature and relative humidity gradually decreased by 58% in 38 weeks whereas linamarin in cassava flour is 100% stable for 6 months. Cyanogens could not be removed from wet gari samples at 30 or 50 °C and were only slowly removed by repeated heating at 100 °C and rewetting. By mixing equal weights of gari (pH 4.1) and low cyanide cassava flour (pH 6.5), wetting and heating at 50 °C for 5 h, the cyanide content was reduced by about one half. Wetting a gari/flour (1:1) sample with 1.5 times its weight of water and standing in a 1 cm thick layer in the sun for 4 h reduced the cyanide content by about one half. This treated mixture may be cooked to prepare stiff porridge with lowered cyanide content, and may help reduce tropical ataxic neuropathy in West Africa.

In 2005 a simple wetting method was developed that reduced total cyanide content of cassava flour 3–6-fold. The method involved spreading wet flour in a thin layer and standing in the shade for five hours to allow evolution of HCN gas. We found that breakdown of linamarin catalysed by linamarase to acetone cyanohydrin, followed by its spontaneous decomposition to HCN and acetone was greatly increased by standing the wet flour in the sun. Treatment for two hours in the sun gave the same amount of total cyanide remaining as five hours in the shade. This rapid treatment in the sun may be more acceptable to rural women in Democratic Republic of Congo, than five hours in the shade. The two methods are offered as alternatives for use in rural Africa. With adequate linamarase present the residual cyanogen remaining after the wetting treatment was acetone cyanohydrin.

A mild method was developed to remove cyanogens from cassava leaves that involved three consecutive steps (1) pounding, (2) standing for 2 h in the sun or 5 h in the shade in the tropics and (3) washing three times in water. Four cassava cultivars were used and the mean residual total cyanide content after steps 1, 2 and 3 was 28%, 12% and 1%, respectively. The pounded cassava leaves retained their bright green colour and texture. The traditional method for removing cyanogens from pounded cassava leaves is by boiling in water which removed all cyanogens in 10 min. However this method caused the pounded leaves to become dull green in colour and would cause considerable losses of vitamins, protein and methionine, which are already in short supply in the diet of poor village people in tropical Africa.