Optimization of Fermentation Condition and Product Characterization in Bioethanol Production from Waste Potato

Abstract

Fulfilling energy demand of generations in accordance with environmental policy and in a sustainable way is a very critical issue that requires a clear attention. For this reason, a promising solution is focusing on renewable energy sources. Bioethanol is one of these renewable energies that can be produced from fermentation of biomass such as waste foods. In the first part of the study, analytical methods were applied for characterization of waste potato which was used as a renewable carbon source for bioethanol production by fermentation. The value obtained from characterization of waste potato was relatively similar with standard and previous literature which implies the presence of component that helps to get possible ethanol production. The obtained result includes: 39.65% starch content, 34.71% of moisture content, 5.823% of ash content, 9.46% protein and 7.33% of fat content. The conversion of waste potato to ethanol was achieved mainly by four process steps: dry milling (physical pretreatment) of waste potato, acid hydrolysis of pretreated waste potato to convert starch into reducing sugar (glucose), fermentation of the sugars to ethanol using Saccharomyces cerevisiae and finally batch distillation of the fermented sugar into final product. In second part of the study, optimization of most significant parameters (temperature, pH and fermentation time) was carried out using Box-Behnken experimental design. The result of optimization indicated that optimal temperature of 32.199 °C, pH 4.066 and incubation time 72.082 hr. at this optimum condition, 34.5% ethanol yield was recorded. Finally, the properties of final product including functional groups FTIR analysis was done and compared with the standard physical and chemical characteristics of bioethanol