Moisture-pressure combination treatments for cyanide reduction in grated cassava

Several cyanide-associated health disorders have been linked with frequent consumption of mildly toxic cassava (Manihot esculenta crantz) products in individuals on a low-protein diet. Production of bread from cassava often involves application of prolonged physical pressure (pressing) to the freshly grated root for several hours. This study aimed to determine effects of pressure and wetting on grated cassava. Six treatments were applied: confining pressure for 12 h, wetting for 4 h at 25 °C, 2 h at 25 °C, 2 h at 40 °C, and 2 h at 50 °C, or each of the above followed by pressure for 12 h. Treatments released cyanide from samples in the order: 2-h wet at 50 °C + pressing >4-h wet at 25 °C + pressing = 2-h wet at 40 °C + pressing >2-h wet at 25 °C + pressing = 4-h wet at 25 °C >12-h pressing. Wetting for 2 h at 50 °C followed by pressure for 12 h reduced cyanide levels by at least 20% more than that of any other treatment. The combination of moisture and pressure enhanced the contact time between linamarin and linamarase to increase the release of hydrogen cyanide.