(622ae) 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]
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[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]
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Bello: Serie Ciencia y Tecnología, 101: 43-76.

[5]
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[6]
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in: http://goo.gl/M2e019.

[7]
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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.