VOL. 6, NO. 1, JANUARY 2011 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences © 2006-2011 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com COMPARATIVE EXTRACTION OF COTTONSEED OIL BY n-Hexane and Ethanol Devesh K Saxena, S. K. Sharma and S. S. Sambi University School of Chemical Technology, GGSIP University, Kashmiri Gate, Delhi, India E-Mail: devesh_saxena@rediffmail.com ABSTRACT Cottonseed is a rich source of oil and protein. Cottonseed oil has gained importance as heart healthy oil as it contains lots of un-saturates. It is accepted as a better medium for frying foods. Presently, n-hexane is the solvent of choice in most of the solvent extraction plants though it has been graded as highly toxic and hazardous for the environment. The present study is undertaken to explore the possibility of using ethanol as a non toxic and green solvent in place of n- hexane. The extraction of cottonseed at different temperatures, solvent-solid ratio and particle size at different time intervals using the two solvents is presented to compare the extraction efficiency of the two solvents. The results indicate that at temperature of 45 o C and solvent to solid ratio of more than 10, ethanol has oil extraction efficiency comparable to hexane. The meal produced in the extraction process is found to have lower gossypol content when ethanol is used. Keywords: cottonseed oil, solvent extraction, n-hexane, ethanol, G. Hirsutum, comparability. INTRODUCTION Cotton is a cash crop for more than 20 million farmers in developing countries of Asia and Africa. It is mainly cultivated to meet the basic requirement for cotton fabrics. Cottonseed is a valuable by-product of the cotton plant and for every kg of cotton fiber, 1.65 kg of cottonseed is produced (Rathore, 2007). Global cotton cultivation in 2009-10 yielded 23.3 million metric tons (MMT) of cotton and around 40 MMT of cottonseed (Cotton Incorporated, 2010, Aug. 13). China tops in production of cotton in the world, whereas India stands second (Shekhar, 2006). Cottonseed contains approximately 18-25% of oil and 20-25 % high quality protein. The global annual production of cotton seed could potentially meet the total protein requirement of nearly half a billion people for a year @50 grams / day (Rathore, 2007) but presently cottonseed is not used in food preparations. It is used in animal feed in regulated manner due to the presence of gossypol. Cottonseed oil is rich in tocopherols which inhibits rancidity development and thus contribute to its stability resulting in a longer shelf life for the product. Cottonseed oil is naturally hydrogenated oil and is suitable for heart due to the presence of palmtic, stearic, mysteric, oleic, linoleic and linoleinic fatty acids in sufficient quantities. Cottonseed oil has also gained importance in food preparations due to its higher smoke point (about 232 o C) compared to other cooking oils and is good for frying food articles (Brien et al., 2005). Refined Cottonseed oil has a mild taste and light golden color. It also finds a number of other non food uses in biodiesel production, in paint industry and as an environmentally accepted lubricant additive to improve the lubricating abilities of the base oil SAE 20 W50 (Ertugrul et al., 2004). Solvent extraction is the commonly used commercial technique to recover oil from oilseeds, Presently n-hexane is the preferred solvent throughout the world due to its extraction efficiency and ease of availability yet hexane has been categorized as a hazardous air pollutant (HAP) by the US Environmental Protection Agency and is included in the list of toxic chemicals (NIOSH. 2007). The maximum permissible limit for n-hexane in oil and the meal are 5ppm and 10ppm, respectively (PFA act 1954). It is very tedious and energy consuming to reduce hexane concentration in the meal up to or below maximum permissible limit. These problems have attracted researchers to find a suitable alternative solvent. A number of solvents and their mixtures like heptane, acetone, ethanol-water azeotrope, methyl-pentane, isohexane, petroleum-ether, trichloroethane, chlorinated hydrocarbons, alcohols etc. for oil extraction from oilseeds have been reported in literature (Ayers et al., 1951; Conkerton et al., 1995; Wan et al., 1995(a) and (b); Gandhi et al., 2003; Maria et al., 2008; Frampton et al., 1967; Kuk. et al., 2005; Kuk, 1998; Sepidar et al., 2009; Johnson et al., 1983). Out of these, use of alcohols is gaining attention due to their higher threshold limit in the environment. Junfung (2010) has reported simultaneous extraction of oil and gossypol using mixture of methanol and hexane thereby lowering gossypol content to 0.014% thereby making the cottonseed cake suitable for feed. Although very good results have been reported by him for extraction of oil as well as gossypol still the hexane content in the cake is not within the acceptable limits. Bhowmick (2003) have advocated the use of isopropanol due to the higher solvency of oil and gossypol in it. In the alcohol series, ethanol is the safest solvent as it is obtained from biological sources by the fermentation process and is placed in the category of GRAS (generally recognized as safe). Very few studies are reported for the use of aqueous ethanol as solvent. Hron et al., (1994) have reported a two step process using 95% ethanol for extraction of oil from cottonseed. The extraction process consists of extraction at lower and higher temperatures; the lower temperature facilitates the reduction of gossypol concentration in the meal while higher temperature facilitates oil extraction. Further, it is reported that at higher temperature the extraction of 84