The Effect of Different Processing Methods on the Residual Cyanide of 'Gari'

Abstract

The effect of different processing methods on the cyanide and residual cyanide content of gari (dry granule made from cassava and widely consumed in Nigeria) was investigated using gari from bitter variety of cassava. The processing methods investigated were 1 (unfermented with oil), 2 (unfermented without oil), 3 (fermented with oil), 4 (fermented without oil). The experimental design was a 2 x 2 factorial in a completely randomized design. The reference cyanide content of the cassava pulp determined immediately after grating was 437.4±15.2mg/kg. Results showed that the crude protein content of the fermented groups (Treatments 3 and 4) were higher than those of the unfermented groups (Treatments 1 & 2). The addition of palm oil increased the ether extract values of the groups with palm oil. Fermentation had a significant effect (P < 0.01) on the cyanide content of the gari. Cyanide content of the treatments at `garification` were 223.29±6.2; 203.16±11.7; 91.78±8.4 and 99.34±8.9mg/kg for treatments 1, 2, 3 and 4 respectively. The effect of palm oil addition on the cyanide content was not significant (P > 0.05). The residual cyanide content of the treatments after one week (7 days) of storage were 31.42±9.2; 33.6±2.6; 25.2±2.8 and 25.8±1.6mg/kg for treatments 1, 2, 3 and 4 respectively. These values were not significantly different (P > 0.05). It was concluded that fermentation was a veritable tool in gari production. Storage of gari for upward of 7 days further provides an enabling condition for the detoxification of cyanide from unfermented groups to safe levels.