CBN-V Video Archives - S2-10
Role of Hydroxynitrilelyase in Development of Cyanogen Free Cassava Foods

Nambisan B. and Sandhya C.

Division of Crop Utilization and Biotechnology, Central Tuber Crops Research Institute, Sreekariyam, Trivandrum- 695017, Kerala, India
prsbn@md4.vsnl.net.in

        The sequential action of the enzymes linamarin and hydroxynitrilelyase is essential for the complete hydrolysis of linamarin to free cyanide in cassava. The activities of these two enzymes could influence the removal of cyanoglucosides during processing. The relative distribution of linamarase and hydroxynitrilelyase and the kinetics of cyanogenesis in different tissues were studied in low and high cyanogen cultivars. The distribution of hydroxynitrilelyase was strikingly different from that of linamarase. The hydroxynitrilelyase/linamarase ratio showed large variation between different tissues, and this was reflected in the rate of cyanogenesis in these tissues. Rapid cyanogenesis was observed in leaf, where activity of both enzymes was high. In rind, acetonecyanohydrin accumulated due to high linamarase activity and negligible hydroxynitrilelyase, while in tuber, the rate of cyanogenesis was lowest due to low activity of linamarase and negligible hydroxynitrilelyase. Addition of purified hydroxynitrilelyase resulted in rapid lowering of the cyanogen content in both rind and tuber, due to faster dissociation of acetonecyanohydrin. The deficiency of this enzyme in root tissues causes accumulation of cyanogens during processing, so addition of hydroxynitrilelyase would ensure higher safety for cassava based food products.

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