Preliminary process design development and economics for dry baker’s yeast plant

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University of Dar es Salaam
Bakers’ yeast is a strategic input in bread manufacture. In this report, the manufacture of dry Bakers’ yeast from molasses which is abundantly available from the cane sugar factories in Tanzania is investigated. Molasses is a principle source of nutrients for the growth of yeast cells but must have a suitable chemical composition for this purpose. Molasses available here is interestingly within the recommended specifications in literature. Back-ground theory on the growth of yeast in relation to the amount of nutrients from the raw materials is given. It is the basis for material and heat balances, equipment design and economics for the process described in this report. At present, all the requirements for Bakers’ yeast in Tanzania are not from imports from Frances, British and W. Germany. On an average, over 100 tons of yeast have been imported annually for the last 6 years. The domestic demand has definitely been higher than the amount imported but does not seem to justify a plant of very large capacity. This report is therefore based on the production of 1 ton of dry yeast per day. A working year is considered to be 300 days and the plant is designed to operate on two shifts per day, employing 17 men (excluding Administrative personnel). It will be situated at a sugar factory site to take advantage of the already existing overhead facilities and services. This is considered to cut down annual operating costs. Only a batch fermentation of molasses solution is considered as the continuous systems are probably more complicated and too expensive for a simple plant of this capacity. The total fixed capital investment is estimated at 23,907,000 Tshs. With annual operating costs for the first year of operation at 5, 512,000 Tshs and rising 10% annually for the next 9 years of plant life. The revenue for the 1st year of operation is 9, 000, 000Tshs and also rises 10% annually. The annual income is taxed 50% at the end of every year and taxation sharts after the 1st year of operation. The plant salvage value is 0 and the plant depreciated linearly over the 10 years of lifetime. The day back period is 7.5 years and Discounted Cash flow rate of return is 5.08%. the breakeven point is 46% plant capacity while the shutdown point is 22% plant capacity. This suggests that the project is viable. Potential investors are very much argued to look into this venture, while the academicians are invariably argued to merge their knowledge with the national attempts to make the project a success.
Available in print form, EAF Collection, Dr. Wilbert Chagula Library, (THS EAF TP460.O5)
Production engineering- yeast, Yeast, Manufacturing processes
Omadi, O.L(1981) Preliminary process design development and economics for dry baker’s yeast plant, Masters dissertation, University of Dar es Salaam, Dar es Salaam