Cyanide profiles of some Nigerian edible mushrooms in the raw and processed states

Abstract

Slices of eight species of Nigerian edible mushrooms, namely, Volvorella vulvacaea, Marasmius spp., Coprinus comatus, Pleurotus squarulotus, Pleurotus ostreatus, Schizophyllum commune, Rigidiporus lignosus and Ganaderma oregonense were analysed for free and bound (glycosidic) cyanide in the raw state as well as after processing. The species of mushroom were processed by soaking in water, boiling, sun drying and oven drying using a combination of gravimetric and colorimetric methods. Except for G. oregonense, all the mushrooms contained toxic levels of free cyanide (133–781mg HCN/kg dry matter) and bound cyanide (219–2711mg HCN/kg dry matter). Soaking slices in water for 24 hours led to 41–99% and 79–93% losses in free and bound cyanide respectively. After boiling for 45 minutes both forms of cyanide were reduced to innocuous levels in slices previously soaked in water for 24 hours. Oven drying was less effective than sun drying in minimising free and bound cyanide, although both processes led to significant losses of cyanide. From toxicological perspectives, edible mushrooms are safest when boiled after prolonged soaking in water.



Key Words: Mushroom, processing, cyanide


[Jnl Medicine & Biomedical Res. Vol.1(2) 2002: 60-64]