Cassava foliage: Chemical composition, cyanide content and effect of drying on cyanide elimination

Abstract

AbstractThe chemical composition and cyanide concentration in the foliage of four cassava cultivars (M Col 113, M Col 22, M Col 1684, CM 342–170) were evaluated at four plant ages (6, 8, 10 and 12 months). The effect on cyanide elimination of sun‐drying on a concrete floor and of oven‐drying at 60°C was also studied, including some observations on the tannin content of dried foliage. The proximal composition, calcium and phosphorus contents, as well as the amino acid composition of dried cassava foliage compared favourably to that of sun‐cured lucerne meal. In most cases, foliage from 6‐to 12‐month‐old plants contained 25 to 30% dry matter, and as dried foliage had 13 to 20% crude protein and 16 to 20% crude fibre. Crude protein and crude fibre were the two chemical constituents which varied the most with plant age. The average gross energy of dried cassava foliage was 4.12 kcal kg−1 with a range of 3.90 to 4.35 kcal kg−1. Sun‐drying eliminated more cyanide than oven‐drying (82 to 94% vs 68 to 76%, respectively) and in addition, most of the cyanide in sun‐dried foliage was free cyanide (62 to 77%) whereas only 24 to 36% was found as such in oven‐dried foliage. Sun‐dried foliage samples had consistently lower tannin content than the corresponding oven‐dried samples.