Performance of yeasts from banana wine and coconut palm wine as compared to those of Tanzania distilleries limited (TDL).

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University of Dar es Salaam
The study covered the following areas: 1. Isolation of yeast from traditional alcoholic beverages and determination of their growth different temperatures. 2. Study of the performance of the yeast isolates in fermenting molasses and glucose as compared to the yeast used by the Tanzania Distilleries Limited (TDL). 3. Ethanol tolerance of the yeast isolates and that used at TDL. 4. Physiological characterisation of yeast isolated from various local alcoholic beverages. In this study a yeast strain from Tanzania Distilleries Limited (TDL) was used to compare the performance of the yeast isolated from local alcoholic beverages. The local alcoholic beverages used in this study were banana wine (i.e. mbege and rubisi) and coconut palm wine. Isolation and purification of yeasts from the above named local alcoholic beverages was done. Growth rates of these isolates were determined and compared with that of TDL yeasts. The results have shown that the yeasts isolated exhibited higher growth rates than that of the TDL yeast. The highest growth rate was exhibited by an isolate from rubisi brew at 37°C (0.69 hr-1 ). The optimum growth temperature for the isolates ranged between 25°C to 37°C; and pH 4.5 - 6'.0. The optimum growth temperature for TDL yeasts is 30°C and pH 5.6. The growth rate for TDL yeast at this temperature (pH 5.6) is 0.45 hr-1. Study on the performance of yeast isolates in fermentation of molasses and glucose at varying conditions was done. All isolates were able to ferment molasses and glucose. Fermentation of molasses using the yeast isolates has shown that an isolate from coconut palm wine produced higher ethanol 7.2% vol/vol at 30°C and pH 4.5. An isolate from Bugandika rubisi fermented molasses and produced 7.0% vol/vol,ethanol at 37°C. In both cases TDL yeasts produced lower amounts of ethanol (6.3% vol/vol) than that produced by .the isolates. At 40°C an isolate from Bugandika rubisi performed better producing 5.9% vol/vol ethanol as compared to TDL yeast which produced 5.3%.vol/vol ethanol. The Gas Chromatograph analysis has shown that ethanol is the sole detectable alcohol from the fermentations done. For the detection limits of the above analysis see appendix 1. Ethanol tolerance of the yeast isolates was analysed and the results have shown that growth of all yeasts were suppressed at 9% vol/vol ethanol where no growth was shown by any yeast strain. Physiological characterisation of the isolates was done by following the standard methods: The isolates showed many characteristics of the Saccharomyces genus except for one isolate from rubisi. The isolates can be employed in clarification of some taxonomic aspects and for the production of strains for industrial ethanol production and for single cell protein.
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Yeast classification, Coconut products, Banana products
Rutaindurwa, W. G. (1996). Performance of yeasts from banana wine and coconut palm wine as compared to those of Tanzania distilleries limited (TDL). Master dissertation, University of Dar es Salaam. Available at (