African Journal of Biotechnology Vol. 4 (7), pp. 689-696, July 2005          
ISSN 1684–5315 © 2005 Academic Journals

Full Length Research Paper

Reduction of the cyanide content during fermentation of cassava roots and leaves to produce bikedi and ntoba mbodi, two food products from Congo

S.C. KOBAWILA, D. LOUEMBE*, S KELEKE, J. HOUNHOUIGAN, C. GAMBA

Faculté des Sciences, BP 69, Brazzaville-Congo / BP 1286, Pointe-Noire, Congo.

*Corresponding author. E-mail: d.louembe@laposte.net. Tel:  00 242 662 05 72 / 00 242 668 69 31, Fax: 00 242 94 39 81.
 

Accepted March, 2005

Cassava roots and leaves constitute energy-rich and protein-rich foods, respectively, for the populations in Central Africa, where they are consumed as staple foods. But cassava roots and leaves contain some cyanide in the form of cyanogenic glucosides, notably the linamarine, which can constitute a poison for the consumers when roots or leaves are processed improperly. Cassava roots and leaves processing in Congo, as in most central African countries, involve fermentation. The fermentation of the cassava roots is a lactic fermentation (pH 3.8) with Lactobacillus as dominant microflora whereas that of the cassava leaves is an alkaline fermentation (pH 8.5) where Bacillus constitute the main microflora. The hydrolysis of cyanogenic glucosides takes place as well in acid medium during the cassava tubers fermentation as in basic medium with the cassava leaves fermentation. The cyanide content decreases during the fermentation of cassava roots and leaves by more than 70% through the activities of the bacterial produced linamarase, allowing the hydrolysis of cyanogenic glucosides. Certain lactic bacteria present in the environment of fermentation are resistant to the strong cyanide concentrations of between 200 and 800 ppm.

Key words: Fermentation, cassava roots, cassava leaves, lactic acid bacteria, bacillus, cyanogenic glucosides.