J Am Oil Chem Soc DOI 10.1007/s11746-015-2634-3 1 3 ORIGINAL PAPER Methyl Esters (Biodiesel) from and Fatty Acid Profile of Gliricidia sepium Seed Oil Gerhard Knothe 1 · Maria Ellenita G. de Castro 2 · Luis F. Razon 3 Received: 15 January 2015 / Revised: 6 March 2015 / Accepted: 6 March 2015 © AOCS (outside the USA) 2015 Keywords Biodiesel · Fatty acid profile · Fuel properties · Gliricidia sepium seed oil · Legume · Methyl esters · Transesterification Introduction With the interest in and use of alternative fuels derived from renewable biological sources continuing to grow, the need to increase their supply has caused an intense search for additional feedstocks. Biodiesel [1, 2], defined as the mono-alkyl esters of vegetable oils, animal fats or other materials composed largely of triacylglycerols and rank- ing among the prime alternative biofuels, is affected by this issue. The current supply of biodiesel suffices to replace only a low percentage of the petrodiesel market. Besides the supply issue, the search for additional biodiesel feed- stocks has been powered by the perceived food vs fuel issue and economics. Thus, besides common commodity veg- etable oils such as palm, rapeseed (canola) and soybean, numerous other potential feedstocks have been investi- gated. Some “alternative” vegetable oils or other feedstocks that have been studied include camelina [3], coriander [4], cuphea [5], desert date [6] jatropha [7], mahua [8], moringa [9], mustard [10], pennycress [11], pongamia [12], pump- kin seed [13], rubber seed [14], Thespesia populnea [15], and, especially under economic aspects, used cooking oils [16, 17] as well as, prominently in recent years, algae [18, 19]. Methyl esters, obtained by transesterification of the triacylglycerol-containing feedstock in the presence of a base catalyst, preferably alkoxide, are the most common form of biodiesel because methanol is in most countries the least expensive alcohol. Thus, biodiesel standards are largely based on the methyl esters. The most commonly Abstract Increasing the supply of biodiesel by defining and developing additional feedstocks is important to over- come the still limited amounts available of this alternative fuel. In this connection, the methyl esters of the seed oil of Gliricidia sepium were synthesized and the significant fuel- related properties were determined. The fatty acid profile was also determined with saturated fatty acids comprising slightly more than 35 %, 16.5 % palmitic, 14.5 % stearic, as well as lesser amounts of even longer-chain fatty acids. Linoleic acid is the most prominent acid at about 49 %. Corresponding to the high content of saturated fatty acid methyl esters, cold flow is the most problematic property as shown by a high cloud point of slightly >20 °C. Otherwise, the properties of G. sepium methyl esters are acceptable for biodiesel use when comparing them to specifications in biodiesel standards but the problematic cold flow properties would need to be observed. The 1 H- and 13 C-NMR spectra of G. sepium methyl esters are reported. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. USDA is an equal opportunity provider and employer. * Gerhard Knothe gerhard.knothe@ars.usda.gov 1 Agricultural Research Service, National Center for Agricultural Utilization Research, US Department of Agriculture, 1815 N. University St., Peoria, IL 61604, USA 2 Biology Department, De La Salle University, Manila, The Philippines 3 Department of Chemical Engineering, De La Salle University, Manila, The Philippines