Effects of drying temperature and loading rates on cyanide elimination from cassava whole‐root chips

Abstract

The effects of three oven drying temperatures (60,70 and SOT), each at three loading rates (10. IS and 20 kg/m') on cyanide elimination from cassava whole-root chips were evaluated. Roots of two cassava cultivars, one with high (M Col 1684) and the other with intermediate (M Col 22) cyanide contents, were used. A total of twenty-seven drying experiments with chips of cv. M Col 1684 and eighteen with M Col 22 were evaluated in two factorial experiments 3 x3 x3, (temperaturex loadingx replicate) and 3 X 3 X 2, respectively. The main factor determining cyanide elimination was the loading rate rather than the drying temperature under these conditions. As the loading increased from 10 to 20 kg/m2 the total and bound cyanide contents of dried chips decreased as a result of the higher cyanide losses. 'IThis effect was statistically significant only with the chips of the high-cyanide-containing cultivar but the same trend was observed with M Col 22. Artificial drying at the temperatures and loadings assayed allowed total cyanide losses of 81 and 69% for chips of cv. M (20122 and M Col 1684, respectively; the residual cyanide content of dried chips of cv. M Col 1684 was three times the maximum permissible level set by the EEC for hydrocyanic acid in cassava products to be used as animal feeds. These experimental results are compared with previously published data on cyanide elimination.

Investigation of effects of different cassava cultivars with respect to hydrogen cyanide content on their starch hydrolysis

“…Also, Arihantana and Buckle (1986) studied cassava detoxification during traditional fermentation process and reported total cyanide loss of 58 -87%. Gomez and Valdivieso (1985) investigated the effect of sun-drying on concrete floor and oven drying on trays on the elimination of cyanide from cassava whole root chips. According to their findings, sundrying eliminated 86-94% of the initial total cyanide and 93 -98% of the bound cyanide, whereas the reduction was found to be 77 -80% and 81 -85% for oven drying at 60 o C, respectively.…”

“…The utilization of cassava roots for both human and animal nutrition appears to be limited by the presence of these cyanogenic glycosides that limit the use of its products and a non-cyanide (acyanophoric) cultivar has not been found (Gomez and Valdivieso, 1985). However, linaminrin is reported to be destroyed during cassava processing: grating, rasping, soaking, drying and cooking at high temperature (White et al, 1998).…”