Response Surface ‎Methodology for Optimization of Ethanol ‎Production from Cocoa Waste

Cocoa waste (CW) is an inexpensive agro-industrial by-product that is available in large quantities in tropical countries such as Malaysia. The rate of ethanol production can be affected by different parameters involved during fermentation. In this study, response surface methodology (RSM) with the full factorial design was used to obtain optimum conditions for bioethanol production using CW as the substrate. The simultaneous saccharification and fermentation (SSF) performed with an isolated microorganism from locally fermented food tapai ubi and tapai pulut. The effect of four independent variables temperature, CW concentration, inoculum size, and pH was investigated. In the optimized condition temperature of 31.7°C, pH 6.0, inoculum size 10.5%, and CW concentration 0.3 g/L, the highest ethanol production was 9.5 ± 1.1. ANOVA analysis revealed that temperature and CW concentration had the most significant effects on ethanol production. In addition, ethanol production was increased in the highest level of pH and inoculum size. Therefore it can be concluded that ethanol production increased from 6.2 ± 0.8 g/L to 9.5 ± 1.1 g/L after optimization.