Effect of non‐enzymic browning, starch and sugars on total cyanide determination in cassava by an enzymic assay

Abstract

Maillard (non-enzymic) browning pigments and gelatinized starch interfered in the assay of total cyanide in cassava products by an alkaline picrate-enzymic method. Interference from browning pigments in cyanide determinations was overcome by adding charcoal followed by filtration, while gelatinized starch was precipitated by the addition of ethanol. Glucose, fructose and maltose but not sucrose also interfered in the assay and produced high total cyanide results. A more specific reaction than alkaline picrate is still required for free cyanide estimations in cassava products.

Studies on the quantification of specific cyanogens in cassava products and introduction of a new chromogen

“…An improved storability of the extracts was suggested. Ikediobi et a1 (1980) tried to replace the pyridine/ pyrazolone color reagent with picrate but this reagent is not very specific for cyanide in the Guignard reaction (Zitnak 1973;Arihantana and Buckle 1986). Bradbury et a1 (1991) managed to replace the use of the expensive enzyme linamarase by an acid hydrolysis, but this resulted in a more laborious and time-consuming assay and sometimes lower recoveries of linamarin supplement.…”

Initial evaluation of a field‐friendly extraction procedure for the enzymatic assay of cassava cyanogens

“…For the Cooke assay, the extraction procedure is as follows: a diced parenchymal sample is blended with a known quantity of extraction medium (normally 0.1 m H 3 PO 4 ), then filtered (usually under vacuum) to give a clarified extract, which is assayed for CNP. A modified medium (containing ethanol) has been developed for the extraction of cassava products containing gelatinised starch (Arihantana & Buckle, 1986). To date, however, no modification of the extraction procedure itself has been reported.…”

Improved enzymic assay for cyanogens in fresh and processed cassava

“…To overcome this problem, Arihantana and Buckle (1986) used a phosphoric acid/ethanol extraction mixture which limited the 'pasting' effect, giving better volumetric recovery. The ethanol was removed by evaporation prior to assay.…”