Optimization of Bioethanol production from cocoa waste by locally isolated microorganism using RSM

Abstract

The purpose of this study is to screen for potential bioethanol producers and to optimize production of ethanol by RSM (Response Surface Method) through various growth parameters. Microorganisms that were able to ferment sugar into ethanol were isolated from local food sources which were Tapai ubi and Tapai pulut. In this study, four types of yeast were used during fermentation which was isolated from Tapai ubi and Tpapi pulut and also selected the best one in terms of highest production of bioethanol before optimization with RSM .Their potential as the microorganism for ethanol production was evaluated and optimized through various growth parameters that were temperature, pH, inoculum size, and cocoa waste Concentration. The cocoa wastes were pretreated using 0.5M sulphuric acid. Ethanol was produced by the isolated yeast during fermentation process using batch culture system in a shake flask. Different growth parameters which have effect on bioethanol production were investigated. The results have showed all these parameters are contributing in bioethanol production. Before optimization the optimum temperature of bioethanol production was 30°C, pH 5.0, inoculum size was 9% (v/v) and Cocoa waste concentration 0.2 g/L where the highest production of bioethanol was 0.0129 g/L/h. After optimization obtained the best condition of productivity and in range of temperature 31 °C, pH 6.0, inoculum size 10.5% (v/v) and Cocoa waste concentration 0.3 g/L meanwhile the highest productivity of ethanol was 0.2050 g/L/h which is higher in compare to before optimization process.