Preliminary plant design and economics for the extraction and purification of mafura nut oil from mafura nuts

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University of Dar es Salaam
A preliminary plant design and economics of a plant for the extraction and purification of Mafura nut oil for edible purposes has been carried out. A plant capacity of 4000 MT/year of edible oil is proposed, with 1000 MT/year of low grade oil and 700 MT/year of Free Fatty Acids (FFA} as by-products to be sold to soap manufacturers. The main raw material is the Mafura nuts from the mafura tree (Trichiliaemetica), a tropical tree found in most parts of the country. Mbeya region, the proposed plant location is currently estimated to be able to supply approximately 20 % of the 10,800MT/year of nuts required to feed the plant. It is assumed that the rest will be obtained from individual farmers and from government mafuru plantations to be set up in advance of the establishment of the plant. The design of the process has been based on mechanical and solvent extraction principles, Fupi's work on the removal of the bitter and emetic principle(s) from the oil, and on the practical experiences gained by the Morogoro based Multipurpose Oilseeds Processing Company. Mechanical expression followed by solvent extraction with n-Hexane has been chosen in favour of both mechanical expression alone and solvent extraction alone because the former method gives a rather low extraction efficiency while the latter is expensive. Degumming of the oil is achieved by mixing with acetic anhydride (0.1% v/v) followed by water (3.0 % v/v) and centrifugation. Neutralization of the Free Fatty Acids in the oil is achieved by use of 1 .OM NaOH followed by centrifugation. The oil is then washed twice with 15 w% portions of 0.25M NaOH and once with 15w % water and centrifuged each time. During the refining process, low grade oil and crude Free Fatty Acids are recovered as by-products. The oil is vacuum dried and vacuum bleached and deodorized and finally filtered thorough polishing filter to packaging or to storage at 550c. The economic viability of the project has been established. With an estimated total capital investment of 47:4 million Tshs s after tax Rate of Return on Investments was found to be 32% with a Discounted Cash Flaw Rate of Return {DCFRR) of 40%. The break-even point was found to be at 50% of plant capacity with a pay-back period of 2½ years and the shut-down point at 28% plant capacity. This economic analysis was arrived at by using the following estimated prices for raw material and products;- Delivered Raw mafura nuts -1.85 Tshs/kg, Edible Mafura oil - 20 Tsh/kg, Low grade oil -10 Tshs/kg FFA-5 Tshs/kg.
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Production engineering, Mafura Nuts, Manufacturing processes
Mwaipopo, L. J. N ( 1981) Preliminary plant design and economics for the extraction and purification of mafura nut oil from mafura nuts, Masters dissertation, University of Dar es Salaam. Available at ( )