Single cell protein can be produced on a number of different substrates, often this is done to reduce the Biological Oxidation Demand of the effluent streams leaving various type of agricultural processing plants. A wide range of substrates can be used to grow microbial proteins (Kuhad et al., 1997). Various materials can be used as a substrate for producing single cell protein (whey, orange peel residue, sweet orange residue, sugarcane bagasse, paper mill waste, rice husks, wheat straw residue, cassava waste, sugar beet pulp, coconut waste, yam waste, banana pulp, mango waste, grape waste, sweet potato (Vaccarino et al., 1989; Swaminathan et al., 1989 ; Bajpai et al., 1991 ; Nwabueze et al., 1987; El-Shawarby et al., 1987; Khaled et al., 1985; Pandey et al., 1988; Aderiye et al., 1988; Aker et al., 1987; Kahlon et al., 1986; Manilal et al., 1991; Malathi et al., 1989; Kuzmanova et al., 1991; Zayed et al., 1992; El Refai et al., 1990; Bugarski et al., 1988; Guo et al., 1989; Rashad et al., 1990; Rodriguez et al., 1993; Yulinery, 1995). Methods available for concentrating include, filtration, precipitation, coagulation, centrifugation, and the use of semi-permeable membranes. These de-watering methods require equipment that is quite expensive and would not be suitable for most small-scale operations. Removal of the amount of water necessary to stabilize the material for storage, in most instances, is not currently economical. Single cell protein must be dried to about 10 % moisture, or condensed and acidified to prevent spoilage from occurring, or fed shortly after being produced.
