Ethanol Production from Non-Food Tubers of Iles-iles (Amorphophallus campanulatus) by Using Separated Hydrolysis and Fermentation

Abstract

The decrease in production and the raise in needs have led to the rise in oil prices. This work investigated the possibility of Iles-iles (Amorphophallus campanulatus) tuber flour, which is rich in carbohydrate con-tent, as a raw material to produce bioethanol. To obtain the maximum ethanol concentration, several parameters had been studied, such as: the concentration of α-amylase and β-amylase in liquefaction and sac-charification processes, respectively, the type of S. cerevisiae enzyme (pure, dry, wet and instant) and weight of Diammonium phosphate (DAP) as a nutrient for S. cerevisiae in fermentation. The result shows that the highest reducing sugar content (12.5%) was achieved when 3.2 ml α-amylase/kg flour and 6.4 ml β-amylase/kg flour were used during liquefaction and saccharification processes. Since the concentration of α- and β-amylase increased, the reducing sugar obtained also increased. The higher sugar content resulted the higher the ethanol concentration in the fermentation broth. Furthermore, the highest concentration of ethanol (9 %v/v) was obtained at 72 h fermentation using the dry S. cerevisiae, at 3.2 ml and 6.4 ml /kg flour of α-amylase and β-amylase enzymes, respectively. From the study of the effect of S. cerevisiae type, it was shown that dry S. cereviseae produced the highest ethanol concentration 10.2% (v/v) at 72 h fermentation. The DAP was used as a nitrogen supply required by S. cerevisiae to growth and as a results can increase the ethanol concentration. The addition of DAP in the fermentation proved that 8.45% (v/v) of ethanol was obtained. This result shows that the proposed tuber flour has the potential a raw material for bioethanol production. © 2014 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)