An improved microdiffusion method with solid-phase detection for the determination of total cyanogens in fresh cassava. Comparison to the method of Cooke (1978)

A microdiffusion method with solid-phase detection for the determination of total cyanogens (=cyanogenic potential, CNp) in fresh cassava roots was developed and evaluated against the classical spectrophotometric method of Cooke (J Sci Food Agric 29 (1978) 345-352). Using seven different cassava cultivars, a significant difference (approx 15%) in the determined CNp was observed only for one of these. The new method offers several advantages over the earlier described spectrophotometric methods. Filtration of homogenates is not necessary, neither is cooling nor hearing, The developed colour is stable on the reaction sheet, so that levels may be measured immediately or when appropriate, and be filed for documentation purposes, Further the solid-phase reaction may be measured in different ways according to the instrumentation available, ie reflectometry as used in this study, or absorption of transmitted light using a TLC-densitometer or a microplate reader. The amount of enzyme (linamarase) used per analysis is lower than for the spectrophotometric assays, giving economic advantages to the present assay. In addition to the extract, only three solutions are used when performing the assay, ie the buffer, the substrate solution for standards, and the enzyme solution. The assay may be run either according to a 'slow' overnight protocol or to a 'fast' protocol at 40 degrees C. (C) 1998 SCI.