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Detoxification of Cassava Leaves by Thermal, Sodium Bicarbonate, Enzymatic, and Ultrasonic Treatments

Latif, Sajid, Zimmermann, Sonja, Barati, Ziba, Müller, Joachim
Journal of food science 2019 v.84 no.7 pp. 1986-1991
ascorbic acid, byproducts, cassava, glucosides, hydrogen cyanide, leaves, sodium bicarbonate, temperature, toxic substances, ultrasonic treatment
Cassava leaves are a valuable source of protein but the cyanogenic potential limits their use as food and feed. Four different treatments were investigated to detoxify cassava leaves. Thermal (55 °C for 6 hr), sodium bicarbonate (0.4% NaHCO₃, 55 °C for 6 hr), enzymatic (0.32% Multifect® GC Extra, 4 hr), and ultrasonic treatments (500 W, 35 kHz, 55 °C, 0.25 hr) reduced the total cyanide (µg HCN equivalents per g fresh leaf or ppm) content by 90%, 93%, 82%, and 84% while the cyanide content reduction in the respective controls was 85%, 90%, 79%, and 84%, respectively. The sodium bicarbonate treatment was found to be the most effective treatment. Therefore, it was further optimized by varying time and temperature. A significant effect on the cyanide content was observed by changing the incubation time while no significant effect of temperature was noticed. Nevertheless, extended incubation time during sodium bicarbonate treatment reduced ascorbic acid content by 7% and 39% when leaves were incubated with sodium bicarbonate for 0.5 hr and 48 hr, respectively. PRACTICAL APPLICATION: Cyanogenic glucosides are the major toxic compound in cassava leaves, which limits their use as food and feed. The methods proposed in this study can be used to detoxify cassava leaves, which are generally considered as an inferior by‐product. Hence, detoxified cassava leaves may contribute to fulfil world protein demand in an eco‐sustainable way.