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African Journal of Biotechnology

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Changes in the nutrient and anti-nutrient content of micro-fungi fermented cassava flour produced from low- and medium-cyanide variety of cassava tubers

G Oboh, CA Elusiyan

Abstract


Comparative studies were carried out on the ability of pure strain of Rhizopus oryzae and Saccharomyces cerevisae to alter the nutritional quality of cassava flour produced from low- and medium-cyanide variety of cassava tuber. Low- and medium-cyanide variety of cassava tubers were collected from International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. These tubers were washed, peeled, grated and aseptically inoculated with pure strains of R. oryzae and S. cerevisae in
nutrient solution, independently, before allowing them to ferment aerobically for 3 days. The fermented mash was subsequently dried and milled into cassava flour. Subsequently, the proximate, mineral and
the anti-nutrient composition of the cassava flour were determined. The results of the study revealed that the unfermented flour from low-cyanide cassava variety had higher protein, fibre, ash, fat, Ca, Na
and K contents, while those produced from medium-cyanide variety, had higher anti-nutrient (tannin, cyanide and phytate), Zn, Mg and Fe contents. However, solid substrate fermentation of the cassava
mash using R. oryzae and S. cerevisae, independently, caused a significant (P < 0.05) increase in the protein and fat content. The nutrient enrichment was significantly higher (P < 0.05) in flour produced
from low-cyanide cassava variety. In addition, S. cerevisae fermentation brought about a higher increase in the nutrient content than R. oryzae fermentation. Conversely, fermentation of the cassava
caused a significant decrease (P < 0.05) in the anti-nutrient content of the flour; although, the level of decrease was more in the flour produced from low-cyanide variety than medium-cyanide variety.
Nevertheless, there was no significant difference (P>0.05) in the ability of the fungi to decrease the antinutrient (except phytate) of the cassava flour. Furthermore, micro-fungi fermentation did not cause a
significant change (P > 0.05) in mineral content (except Mg and K) of the fermented cassava flour. Therefore, unfermented cassava flour produced from low-cyanide cassava tubers had high nutrient
composition and low anti-nutrient content, and more susceptible to micro-fungi nutrient enrichment and detoxification than medium-cyanide variety. Furthermore, S. cerevisae was more efficient in the
nutrient enrichment of the cassava flour than R. oryzae.



http://dx.doi.org/10.5897/AJB2007.000-2336
AJOL African Journals Online