Cyanide in garri. 1. Distribution of total, bound and free hydrocyanic acid in commercial garri, and the effect of fermentation time on residual cyanide content

Random samples (n = 108) of commercial garri collected from the main garri-producing communities in Nigeria were analysed for total, free and bound hydrocyanic acid (HCN) content. The samples contained highly variable levels of total HCN (1.3–38.6 mg HCN/kg) and free HCN (1.2–32.4 mg/kg). Frequency distribution of the total cyanide levels showed that about 80% of the samples contained less than 20 mg HCN/kg; 13% contained 20–30 mg HCN/kg and the remaining 7% contained 30–40 mg HCN/kg. About 90% of all samples contained ≥10 mg/kg bound HCN. There were distinct inter- and intra-communal variabilities in the residual HCN levels of garri, which apparently arose from wide variabilities in the cassava varieties in use, differences in agronomic/environmental factors with respect to cassava production, and a clear lack of standardisation of the processing techniques before and during garrification (frying).