Research Article Improvement of fuel properties of cottonseed oil methyl esters with commercial additives* Hem Joshi 1 , Bryan R. Moser 2 , Shailesh N. Shah 2 , Anurag Mandalika 1 and Terry Walker 1 1 Biosystems Engineering, Clemson University, Clemson, SC, USA 2 United States Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, Peoria, IL, USA The low temperature operability and oxidative stability of cottonseed oil methyl esters (CSME) were improved with four anti-gel additives as well as one antioxidant additive, gossypol. Low temperature operability and oxidative stability of CSME was determined by cloud point (CP), pour point (PP), cold filter plugging point (CFPP), and oxidative stability index (OSI). The most significant reductions in CP, PP, and CFPP in all cases were obtained with Technol 1 , with the average reduction in temperature found to be 3.9 8C. Gunk 1 , Heet 1 , and Howe’s 1 were progressively less effective, as indicated by average reductions in temperature of 3.4, 3.0, and 2.8 8C, respectively. In all cases, the magnitude of CFPP reduction was greater than for PP and especially CP. Addition of gossypol, a polyphenolic aldehyde, resulted in linear improvement in OSI (R 2 ¼ 0.9804). The OSI of CSME increased from 5.0 to 8.3 h with gossypol at a concentration of 1000 ppm. Keywords: Biodiesel / Cottonseed / Fatty acid methyl esters / Gossypium hirsutum / Gossypol Received: December 22, 2009; Revised: March 9, 2010; Accepted: March 16, 2010 DOI: 10.1002/ejlt.200900291 1 Introduction Cottonseed (Gossypium hirsutum L.) oil is vegetable oil that is extracted from seeds of the cotton plant. Endogenous anti- oxidants normally found in vegetable oils primarily consist of tocopherols, with other antioxidant constituents present in lesser amounts such as ascorbic acid, flavonoids, catechins, and other minor components [1]. Cottonseed oil (CSO) is unique in that it contains a small percentage (0.1 to 0.2% of crude oil) of gossypol (Fig. 1), which has been demonstrated to possess antioxidant properties [2–5]. To date the influence of exogenous gossypol on the oxidative stability of biodiesel has not been investigated. Biodiesel is defined as the monoalkyl esters of long-chain fatty acids prepared from vegetable oils, animal fats, or other lipids [6–8]. Advantages of biodiesel over conventional petroleum diesel fuel (petrodiesel) include derivation from renewable feedstocks, displacement of imported petroleum, superior lubricity and biodegradability, lower toxicity, essen- tially no sulfur content, higher flash point, and a reduction in most exhaust emissions. Disadvantages include inferior oxi- dative and storage stability, lower volumetric energy content, reduced low temperature operability, and higher oxides of nitrogen exhaust emissions [6, 8]. Many of these deficiencies may be mitigated through cold flow improver [9, 10] and antioxidant [11, 12] additives, blending with petrodiesel [10, 13], and/or reducing storage time [14]. Biodiesel must satisfy accepted fuel standards (Table 1) such as ASTM D6751 [7] in the United States or the Committee for Standardization (CEN) standard EN 14214 [15] in Europe before combustion in diesel engines. CSO has been demonstrated as a suitable feedstock for biodiesel production, but issues such as relatively poor low- temperature performance and oxidative stability remain unresolved [2, 16–19]. The primary objectives of the current Correspondence: Terry Walker, 111 Biosystems Research Complex, Clemson University, Clemson, SC 29634 USA E-mail: walker4@clemson.edu Fax: 1-864-656-0338 Abbreviations: AV, acid value; CFPP, cold filter plugging point; CP, cloud point; CSME, cottonseed oil methyl esters; CSO, cottonseed oil; FA, fatty acid; FAME, fatty acid methyl esters; HHV, higher heating value; IV, iodine value; LHV, lower heating value; OIT, oxidation induction time; OOT, oxidation onset temperature; OSI, oil stability index; PDSC, pressurized differential scanning calorimeter; PP, pour point. *Disclaimer: Product names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable. 802 Eur. J. Lipid Sci. Technol. 2010, 112, 802–809 ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ejlst.com