Protein enrichment of cassava by-products through solid state fermentation by fungi

Nigeria stands as the world's foremost cassava producer with about 26 million tones (FAO, 1993). The leaves and peels, which are by-products of harvesting and processing, constitute 25% of the whole plant. These by-products and the flour constitute a potential source of livestock feed ingredient. The utilization of cassava and it by-products for livestock feeding has long been realized. Various authors have reported their use for feeding poultry (Ravindran, 1991; Sarwat et al, 1988, Long and Adetola, 1983), Pigs (Iyayi, 1986; Iyayi and Tewe, 1988) and ruminants (Smith, 1988). But cassava will be most beneficial for feeding monogastric animals. The major limitation in the use of cassava for monogastric feeding is its low protein content. The flour for example contains about 3.6% protein and the peels about 5.5%. Though the leaves are fairly high in protein with an average value of 21%, it is desirable for this level to be improved. Because of the low protein of cassava products their use in animal feeding usually requires the supplementation of such diets. Protein enrichment of cassava through less expensive means is therefore desirable. Fungal fermentation has been identified as an inexpensive tool for increasing the protein level of substrates in solid state. The attractive characteristics in the use of microorganisms for single cell protein include (1) their fast growth rate even in semi solid and solid media; (2) their high level of protein; (3) their comparable good nutritional values and (4) their easy genetically modification to growth under specific conditions on particular substrates. This study investigated changes in the protein levels of cassava pulp (flour), peels and leaves following solid state fermentation with Aspergillus niger , Saccharmyces cerevisie , Rhizomucor miehei and Mucor strictus .