ABSTRACT
Bio-ethanol is one of the energy sources that can be produced by renewable sources. Potato starch wastes were chosen as a renewable carbon source for ethanol fermentation because it is relatively inexpensive compared with other feedstock considered as food sources. However, saccharification processes are needed to convert starch of potato into fermentable or reducing sugars before ethanol fermentation. In this study, hydrolysis of potato starch wastes and growth parameters of the ethanol fermentation were optimized to obtain maximum ethanol production by S. cerevisiae S288c. The ratio of plant material to acid solution of 1:10 (w/v). Results demonstrated that 0.5% H2SO4, 1% H2SO4, 2% H2SO4 and 3% H2SO4 at 121ºC for 20 min by autoclave were enough to hydrolyze all starch contained in the potato starch wastes. The maximum yield of reducing or fermentable sugars was 125.8 mg/g obtained in 0.5% H2SO4. The minimum yield was 53 mg/g obtained in 3% H2SO4. The yield of bioethanol production by S. cerevisiae S288c was (51.37 mg/g) was achieved at pH 5.5, temperature of 30⁰C and inoculums size of 10% (v/v) after 72 hours of fermentation