Ethanol fermentation from solid waste of tapioca (onggok) by Aspergillus niger and Zymomonas mobilis

Abstract

The aims of this research were to know the best concentration of onggok flour to produce maximum reduction sugar concentration by Aspergillus niger and efficiency of ethanol production from reduction sugar as the product of onggok flour saccharification by Zymomonas mobilis, and the ethanol concentration which produced. The framework of this research was cassava starch in onggok can be used as substance which yielded ethanol by fermentation. The ethanol yielded serves as an alternative substitution fuel for fossil fuel. This research was done in two stages; they were saccharification by A. niger and ethanol fermentation by Z. mobilis. At saccharification stage there were four level of onggok flour concentration: 10%, 20%, 30% and 40%. The inoculum concentration of A. niger 10% (v/v) and the amount of spore about 3.3x106 spore/mL, was inoculated each concentration of onggok flour, with the temperature of incubation 500C and this process taken five days. Parameters have been used were starch concentration before and after saccharification process, reduction sugar concentration, and pH conducted by each, every 24 hours. Stage of ethanol fermentation used concentration of Z. mobilis 10% (v/v), with the cell amount 5.1x107 cell/mL. Reduction sugar concentration from saccharification product that used 1.9352% and fermentation was done in 72 hours. Parameters were concentration of ethanol and reduction sugar each, every 24 hours and the growth of Z. mobilis cell every 24 hours. This research concluded that concentration of onggok flour 10% produced maximum reduction sugar concentration on the third day that was 1.1842%. Ethanol concentration yielded was 0.7% (v/v) and efficiency of ethanol that was produced from reduction sugar from saccharification of onggok flour was 83% during 72 hours fermentation.