Ethanol Production from Cocoyam (Xanthosoma sagittifolium). Design and Analysis

Corresponding author: ccardonaal@unal.edu.co

Xanthosoma sagittifolium (L.) Schott commonly known as cocoyam (Elephant Ear, Taro, and Malanga) belongs to the family of Araceas, originated in Central America and extensively grow in tropical regions [1]. The main producing regions in the world are West Africa, Asia and Oceania. Nigeria, China and Ghana are the leading countries in production with more than 1'300.000, 1'182.000, and 900.000 tons per year respectively [2, 3]. Currently in Colombia, this tropical plant is not extensively commercialized and is mostly grown around the land as a weed being the current uses mainly directed for feeding farm animals with an approximate production of 200 tons per year for farm animals feeding and only 20 tons per year for human food, sales and agroindustry [4]. However the use is limited to leaf and roots (tubers) are discarded. This discarded part contains about 15 and 39 percent of carbohydrates, 2-3 percent of protein and 70-77 percent of water. The potential of these roots can be used to obtain starches as value added product [5]. The average starch content of cocoyam is about 25% w/w [1]. That compared to others tubers such as potato (15%) [6] and yucca (18%) [7] can be considered a high value.

To understand the possibilities of this raw material, experimental work was done. The initial step of the process consisted in the pretreatment (including washing, peeling, grinding and gelatinization) of the plant in order to obtain the starch. Then, an enzymatic hydrolysis using α-amylase and glucoamylase enzymes was performed in order to convert the starch into sugars. The resulting stream was used for an alcoholic fermentation with Saccharomyces cerevisiae in a 1.5 L fermentor (Biotron LiFlus Autoclavable Fermentor of the brand Hanil Science Industrial) [8].

The experimental data obtained such as process conditions, conversion of starch and fermentation yield was used to assess the production process by means of the commercial software Aspen Plus V8.2 (ASPEN TECHNOLOGY USA). The economic evaluation was carried out using the commercial software Aspen Process Economic Analyzer V8.2 (ASPEN TECHNOLOGY USA). The environmental evaluation of the process was carried out using the software WAR GUI (Chemical Process Simulation for Waste Reduction) [9]. This environmental analysis is based in four main aspects which are: Human Toxicity Potential by Ingestion (HTPI), Terrestrial Toxicity Potential (TTP), Aquatic Toxicity Potential (ATP) and Acidification Potential (AP), correlating them into a total index, the Potential Environmental Impact (PEI) of process [10].

The obtained yields as well as the techno-economic and environmental analysis demonstrated that cocoyam can be an effective raw material in the production of ethanol. Additionally, compared to other starchy materials, cocoyam is not commonly used as a product for human food resulting in a process that does not affect food security.

REFERENCES

[1] Giacometti, D., & León, J. (s.f.). La agricultura amazónica caribeña. Consulted on March 28^th of 2015. Available in: http://goo.gl/ayJzqu.

[2] Food and Agriculture Organization of the United Nations. (1990). Roots, tubers, plantains and bananas in human nutrition. Rome: FAO Italy.

[3] Onwueme, I. C., & Charles, W. B. (1994). Tropical Root and Tuber Crops: Production, Perspectives and Future Prospects. Rome: Food and Agriculture Organization of the United Nations.

[4] Gómez, M., & Acero Duarte, L. E. (2002). Guía para el cultivo y aprovechamiento del bore Alocasia macrorrhiza (Linneo) Schott. Convenio Andrés Bello: Serie Ciencia y Tecnología, 101: 43-76.

[5] United States Department of Agriculture. (s.f.). Germplasm Resources Information Network (GRIN). Consulted on March 28^th of 2015.  Available in: http://goo.gl/cfxIF6.

[6] Potatoes Goodness. (2014). Potatoes Goodness. Consulted on April 18^th of 2015. Available in: http://goo.gl/M2e019.

[7] Rivera, M. A. (2012). Universidad Tecnológica de Pereira. Consulted on April 18^th of 2015. Available in: http://goo.gl/5n6cI5.

[8] Cardona, C. A., Sanchez, O. J., & Gutierrez, L. F. (2009). Process synthesis for fuel ethanol production. CRC Press.

[9] United States Environmental Protection Agency. (2014). WAR GUI V1.0.17. Chemical Process Simulation for Waste Reduction: WAR.

[10] Quintero, J. A., Moncada, J., & Cardona, C. A. (2013). Techno-economic analysis of bioethanol production from lignocellulosic residues in Colombia: a process simulation approach. Bioresource technology, 139: 300-307.