Cyanogen removal from cassava roots during sun-drying

Linamarin levels in sun-drying cassava root pieces showed an exponential decrease, parallel with the moisture loss, and stabilized when moisture levels reached about 15%. Linamarin degradation in thin root segments was significantly slower and less complete than in thick ones. Disinfected longitudinal root halves, oven-dried at 40 degrees C for 24 h, had significantly higher residual linamarin levels than the matched ones subjected to humid incubation at 25 degrees C. Interrupting for one or two days the sun-drying of peeled roots resulted in significantly lower residual levels of linamarin and of cyanohydrins plus HCN. Linamarin degradation was greater when the interruption was earlier or longer. The rate of dehydration influences linamarin degradation negatively - mechanisms are discussed. Cyanohydrin removal was completed by prolonged drying. Sun-drying is not very effective in linamarin removal, and speeding up the drying process, e.g. by reducing the size of the pieces, aggravates this. There is a potential for increasing the effectiveness of cyanogen removal by reducing the initial drying rate, followed by thorough final drying. (C) 1996 Elsevier Science Ltd.