Initial evaluation of a field-friendly incubation procedure for the colorimetric assay of cassava linamarase

The Cooke colorimetric assay of cassava linamarase activity is temperature- and time-inflexible, making ``real time'' monitoring of linamarase activity in remote cassava-processing sites practically impossible. A modified incubation procedure is described, in which the 30 degrees C linamarase incubation step is terminated through acidification, yielding a stable cyanohydrin solution. Using partially purified linamarase as a ``standard extract'', the solution - held for up to 21 days at ambient/refrigeration temperatures before colorimetry showed reductions of up to 21% compared with the standard Cooke assay. In a separate trial, a strong linear relationship (r(2) > 0.95) was observed between recorded linamarase activity values and incubation temperature in the 25-40 degrees C range, indicating that incubation may take place in remote processing sites without a water bath, and resulting data may reliably be adjusted in keeping with the standard 30 degrees C incubation assay. The novel procedure thus appears to offer a satisfactory ``field-friendly'' means of assaying linamarase activity. (c) 2007 Elsevier Ltd. All rights reserved.