Removal of Cyanogenic Glycoside from Cassava during Controlled Drying

Abstract

Sweet cassava from the Cook Islands was washed, peeled, and hammer milled. It was spread on metal trays to a thickness of about 2 mm and kept in an enclosed transparent tunnel for 6 h in the sun to encourage endogenous linamarase activity. The end covers were removed and normal solar tunnel drying continued for 2 to 3 days or until quite dry. The temperature of the cassava pulp, the relative humidity in the tunnel, and weight of the cassava pulp were measured at regular intervals. It was found that the temperature of the cassava pulp and relative humidity in the enclosed tunnel rose rapidly to a level that caused the maximum level of linamarase activity. At the end of the 6-h period of fermentation, the total cyanide levels had reduced to well below the 10 ppm on a dry matter basis as recommended by the Codex Alimentarius Commission for food applications of cassava. Solar drying was continued until the moisture content in the product reached a safe level for storage.

Keywords:

• Cassava
• Cyanide reduction
• Detoxification of cassava
• Fermentation
• Solar tunnel drying