Utilization of Iles-Iles and Sorghum Starch for Bioethanol Production

Int. Journal of Renewable Energy Development 3 (2) 2014: 83-89 P a g e | 83 Contents list available at IJRED website Int. Journal of Renewable Energy Development (IJRED) Journal homepage: http://ejournal.undip.ac.id/index.php/ijred Utilization of Iles-Iles and Sorghum Starch for Bioethanol Production Kusmiyati* and Agus Sulistiyono Renewable Energy Research Centre, Department of Chemical Engineering, Faculty of Engineering, Universitas Muhammadiyah Surakarta, Kartasura, INDONESIA ABSTRACT: The aims of this study were to convert the starches from iles-iles tubers (Amorphophalus campanulatus) and sorghum grains (Sorghum bicolor L) into bioethanol as an alternative energy. Both of these agricultural products contains a high content starches and they do not use as the major foods in Indonesia. To find out the maximum ethanol concentration and yield, both the raw materials were converted to ethanol on various process variables including the concentration of flour substrate solution (100-300 g/L), β-amylase enzyme concentration (0.8 - 6.4 ml/kg of flour ), the concentration of dry yeast S. cerevisiae (215 g), and fermentation time (72-168 hours). The results showed that at the flour substrate concentration of 250 g/L produced the maximum ethanol contents of 100.29 g/L and 95.11 g/L for iles-iles and sorghum, respectively. Effect of β-amylase enzyme in the saccharification process showed that at concentration of 3.2 ml/kg the maximum reducing sugar content of 204.94 g/L and 193.15 g/L for iles-iles and sorghum substrate, respectively were generated therefore it was corresponding to the maximum ethanol production. The concentration effect of dry yeast S. cerevisiae in the fermentation stage for the iles-iles and sorghum substrate revealed that the maximum ethanol obtained at 5 g yeast activated in 100 ml medium starter resulted the highest ethanol content 100.29 g/L 95.11 g/L for iles-iles and sorghum substrate, respectively. To determine the effect of fermentation time on ethanol yield from iles-iles and sorghum substrate, the fermentation process were performed at 3, 5, and 7 days. The maximum ethanol fermentation was obtained at 5 days fermentation. The ethanol yield is calculated by weight of ethanol is formed (g) divided by the weight of flour (g). Based on the experiment results, conducted, generally the highest ethanol yield of iles-iles was higher than that of sorghum flour. The highest yield (g/g) iles-iles and sorghum flour were 71.25 and 68.92 respectively. Keywords: bioenergy, bioethanol, iles-iles, sorghum, S. cerevisiae Article History: Received January 21, 2014; Received in revised form March 24, 2014; Accepted June 11, 2014; Available online How to Cite This Article: Kusmiyati & Sulistiyono, A. (2014) Utilization of Iles-Iles and Sorghum Starch for Bioethanol Production. Int. Journal of Renewable Energy Development, 3(2), 83-89. http://dx.doi.org/10.14710/ijred.3.2.83-89 1. Introduction World petroleum consumption has increased about 5-6% per year based on the assumption of increased in the consumption of gasoline in the world in 1990-2001 from 3.6 to 6.6 MT (Prasad et al. 2007). In Indonesia, the consumption of gasoline reached 17.5 billion L/year which 30% comes from imported of oil producer countries (Bustaman 2008). An increasing of oil consumption causes the depletion of petroleum reserves. Therefore, alternative fuels are required to substitute petroleum. One of the alternative fuel that has been developed in the world is bioetanol. Bioetanol is a bioenergy derived from plants, having similar properties with a petroleum fuel. Bioethanol is promising fuel as its availability in an agricultural country like Indonesia therefore it could increase revenues in the agricultural sector (Sa´nchez & Cardon 2008). Compared with petroleum, bioethanol fuel has a colorless liquid, having a calorific value of 2/3 of the gasoline, having a high octane value. For the environmental aspects, bioethanol is biodegradable liquid which produces no air pollution because it can be oxidized to be carbon dioxide and water with a little carbon monoxide (Voca et al. 2009). Mixing of ethanol with the gasoline fuel will result in more complete * Corresponding author: (+62) 271 717417 Email: © IJRED – ISSN: 2252-4940, 15 July 2014, All rights reserved Citation: Kusmiyati & Sulistiyono, A. (2014) Utilization of Iles-Iles and Sorghum Starch for Bioethanol Production. Int. Journal of Renewable Energy Development, 3(2), 83-89 doi: 10.14710/ijred.3.2.83-89 P a g e | 84 combustion thereby reducing gas emissions (Manikandan & Viruthagiri 2010). Mixing gasoline and bioethanol do with the composition of 10% ethanol with 90% premium called as an EXX (Zamora et al. 2010). Bioethanol is produced from the fermentation of materials containing sugar or starch such as sugarcane, cassava, maize, sorghum and cellulose using yeast (Kargi & Ozmihci 2006). The process for bioethanol production may use simple to high technology depends on the source of raw materials containing sugar, starch, and the most difficult is the lignocellulosic material. For lignocellulosic material, it goes through the pretreatment stage to degrade cellulose and lignin molecules. The next stage is enzymatic hydrolysis using α-amylase (liquefaction) and β-amylase (saccharification). Then, the hydrolysed solution is fermented using microorganism (yeast), and distilled to obtain high purity of ethanol as a fuel (Verma et al. 2000). The simplest process can be applied to the raw material of sugar and molasses (a by product of sugar mills) that is directly fermented without hydrolysis. Currently, the most ethanol plants in Indonesia use molasses as feed stock therefore the molasses dependency as feedstock and high demand of the molasses cause problems in the limitation of its availability (Suhardi 2010). Alternative raw material is required to overcome a lack of raw material supply and high prices molasses although bioethanol production from molasses feedstock is the simple process (Cazetta et al. 2007). Meanwhile, tubers and grains have been used, one of which, corn became the main raw material of bioethanol in the USA. However, the usage of corn for food make the corn usage as an energy lead to rising corn prices and the food cricis (Morris & Brittany 2009). Cassava is also currently widely used as food so it led to drawback when the cassava used as raw material for bioethanol (Kargi and Ozmihci 2005). Besides corn, cassava and molasses, alternative bioethanol feedstock is desirable from material that non-food crop, low cost, and easily grown on nonproductive land. In this study, As shown in Fig. 1, ilesiles tubers (Amorphophalus campanulatus) and sorghum grain (Sorghum bicolor L) were used as raw material for bioethanol. Sorghum and iles-iles are possible to be developed for bioethanol feedstock due to its advantages such as easy in the cultivation because it can live in all land types, resistant in all weather conditi (...truncated)