An enzyme-based dip-stick for the estimation of cyanogenic potential of cassava flour

An enzyme-based dip-stick for cyanogenic potential determination was constructed by gluing three pieces of chromatography paper impregnated with cassava leaf linamarase, phosphate buffer pH 8 and alkaline picrate solution, respectively, onto a plastic strip measuring 10 mm × 45 mm. Using different concentrations of linamarin as reference (equivalent to 0.5–40 μg HCN), the change in colour of the picrate paper was readily distinguishable. Beyond 40–80 μg HCN, it was difficult to differentiate the colour of the picrate paper with accuracy. For quantitative estimation, the colour from the picrate paper was eluted with water and its absorbance measured at 510 nm. Using the dip-stick in conjunction with different types of reaction vessels, it was possible to determine the cyanogenic potential (expressed as mg HCN kg−1) of cassava flour. The method was simple to use. It could easily handle large numbers of samples and it seems suitable for field work.