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 determinati on of total cyanogens (=cyanogenic potential, CNp) in fresh cassava ro ots was developed and evaluated against the classical spectrophotometr ic method of Cooke (J Sci Food Agric 29 (1978) 345-352). Using seven d ifferent cassava cultivars, a significant difference (approx 15%) in t he determined CNp was observed only for one of these. The new method o ffers several advantages over the earlier described spectrophotometric methods. Filtration of homogenates is not necessary, neither is cooli ng 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 ma y be measured in different ways according to the instrumentation avail able, ie reflectometry as used in this study, or absorption of transmi tted light using a TLC-densitometer or a microplate reader. The amount of enzyme (linamarase) used per analysis is lower than for the spectr ophotometric assays, giving economic advantages to the present assay. In addition to the extract, only three solutions are used when perform ing the assay, ie the buffer, the substrate solution for standards, an d the enzyme solution. The assay may be run either according to a 'slo w' overnight protocol or to a 'fast' protocol at 40 degrees C. (C) 199 8 SCI.