Detection of cyanide and comparison of two methods for its detoxification in cassava (Manihot esculenta Crantz)

Abstract

Cassava (Manihot esculenta Crantz) is an agricultural product widely
diffused in most of the tropical countries. However, its consumption could aggravate
a variety of health problems caused by insufficient iodine in the diet, such
as bocium, mental handicap and cretinism, due to the presence of significant
quantities of cyanogenic compound in the roots and leaves of different varieties
of this plant. That is why a methodology for the qualitative and quantitative determination
of cyanide (HCN) in the cassava, using the Head Space-Gas Chromatography
technique, is proposed. The HCN content was determined in a cassava
sample without a detoxification method (shell: 40 ppm and mass: 2 838 ppm,
Response Factor (RF): 4,86 and time of analysis 90 min), using a gas chromatograph
with packed columns and flame ionization detector. This was the technique
used to compare the influence of two traditional processing methods for
the removing of cyanogenic glycosides: The biofermentation followed by sundrying
(shell: 0 ppm and mass: 0,4 ppm) and of the direct sun- drying (shell:
8 ppm and mass: 2 037 ppm), in the final concentration of HCN of the samples, by
analyzing the shells and the eatable mass after having processed. It was possible
to reduce the HCN content applying both detoxification methods, being observed
that the shell still contained more HCN than the eatable part after having been
processed. It was concluded that the biofermentation is the most effective method
for cassava detoxification because it guarantees products with very little residual
HCN.