Cyanide reduction pattern of cassava (mannihot Esculenta) as affected by variety and air velocity using fluidized bed dryer

Abstract

Detoxification of two cassava varieties (TMS30572 and TMS98/0581) by varying drying temperature and air velocity to produce cassava chips was studied at the Department of Food Science and Technology, Federal University of Technology Akure, Ondo; State Nigeria. Quantitative determination of total cyanide (HCN) in cassava chips was carried out using alkaline titration method. Results show that varieties and air velocity interactions highly significantly reduced (P≤0.05) the total cyanide content in the dried chips. Drying at temperature of 40 oC, air velocity of 2.03 m/s, 2.25 m/s, 2.45 m/s and 2.75 m/s reduced the cyanide content from 8.19 mg/kg to range between 2.53 mg/kg-1.07 mg/kg; at temperature of 50 oC at same air velocity gave result of 4.05 mg/kg-1.63 mg/kg; at temp of 60 oC same set of air velocity gave 6.75 mg/kg-1.01 mg/kg and temperature of 70 oC at same air velocity of 7.08 mg/kg - 1.87 mg/kg for TMS30572. TMS98/0581 at temperature of 40 oC, 50 oC, 60 oC and 70 oC and air velocity of 2.03 m/s, 2.25 m/s, 2.45 m/s and 2.75 m/s gave result of 7.43 mg/kg-3.04 mg/kg; 0.45 mg/kg-0.67 mg/kg;0.68 mg/kg-0.59 mg/kg and 0.59 mg/kg respectively. It was noted that total HCN content in cassava chips can be substantially reduced by drying at temperature of 70 oC and air velocity of 2.75 m/s for TMS30572 and temperature of 60 oC and 70 oC at air velocity of 2.75 m/s. This study shows the importance of air velocity on drying for achieving a save level of HCN on dried cassava chips.