Cyanide content of the leaves and stems of edible aroids

Abstract

AbstractThe edible aroids taro (Colocasia esculenta), tannia (Xanthosoma violaceum), giant taro (Alocasia macrorrhizos), giant swamp taro (Cyrtosperma chamissonis) and elephant foot yam (Amorphophallus paeonifolius) have been shown to contain varying amounts of cyanide in their leaves and stems using a screening assay and a more accurate acid hydrolysis method. The cyanogenic glucoside triglochinin (previously identified in giant taro) was found to be less stable to acid hydrolysis (requiring only 15 min) compared with 50 min hydrolysis for linamarin and lotaustralian (from cassava) under the same experimental conditions. The amounts of cyanide present in the leaves (0‐3 mg HCN/100 g fresh weight) and in the stems (0—0.3 mg HCN/100 g fresh weight) of Colocasia and Xanthosoma are only about 1‐5% of that found in cassava leaves and tubers and are not a cause for concern for human nutrition. Cyrtosperma stems and Amorphophallus leaves contain only small amounts of cyanide. In contrast, all Alocasia varieties contained much more cyanide in leaves (2‐30 mg HCN/100 g fresh weight) and in stems (0.5‐4 mg HCN/100 g fresh weight).