ISHS Acta Horticulturae 375: International Workshop on Cassava Safety
FURTHER IMPROVING THE ENZYMIC ASSAY FOR CYANOGENS IN CASSAVA PRODUCTS |
| Author: | A.J. Alexander Essers |
| Keywords: | Cassava, linamarin, cyanide, analysis, König reaction, isonicotinate |
| Abstract:
A commonly used assay for routine determination of cyanogens in cassava is the enzymic assay developed by Cooke (1979), and improved by O'Brien et al. (1991). It compared well with earlier methods and was further improved by more acceptable coloration and more accurate calculation of the cyanogenic glucosides and cyanohydrins (Essers et al., 1993). Isonicotinate/1,3-dimethyl barbiturate, the reagent used in the König reaction, was tested and found to have the following advantages over pyridine/pyrazolone, the color reagent used by Cooke and O'Brien et al.: it is less toxic and does not release repulsive vapors; it is quicker, cheaper and easier to handle; it has increased sensitivity and can be stored for longer. The new coloration has been applied successfully in laboratories in Uganda, The Netherlands and Malawi. An assay protocol is summarised. At Wageningen Agricultural University, the new assay was automated using a Gilson automated pipette station. The need for further improvements is discussed. | |
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