Journal of the American Oil Chemists' Society

, Volume 81, Issue 1, pp 83–89

In situ alkaline transesterification: An effective method for the production of fatty acid esters from vegetable oils

  • Michael J. Haas
  • Karen M. Scott
  • William N. Marmer
  • Thomas A. Foglia


The production of simple alkyl FA esters by direct alkali-catalyzed in situ transesterification of the acylglycerols (AG) in soybeans was examined. Initial experiments demonstrated that the lipid in commercially produced soy flakes was readily transesterified during agitation at 60°C in sealed containers of alcoholic NaOH. Methyl, ethyl, and isopropyl alcohols readily participated in the reaction, suggesting that the phenomenon is a general one. Statistical experimental design methods and response surface regression analysis were used to optimize reaction conditions, using methanol as alcohol. At 60°C, the highest yields of methyl ester with minimal contamination by FFA and AG were predicted at a molar ratio of methanol/AG/NaOH of 226∶1∶1.6 with an approximately 8-h incubation. An increase in the amount of methanol, coupled with a reduced alkali concentration, also gave high ester yields with low FFA and AG contamination. The reaction also proceeded well at 23°C (room temperature), giving higher predicted ester yields than at 60°C. At room temperature, maximal esterification was predicted at a molar ratio of 543∶1∶2.0 for methanol/AG/NaOH, again in 8 h. Of the lipid in soy flakes, 95% was removed under such conditions. The amount of FAME recovered after in situ transesterification corresponded to 84% of this solubilized lipid. Given the 95% removal of lipid from the soy flakes and an 84% efficiency of conversion of this solubilized lipid to FAME, one calculates an overall transesterification efficiency of 80%. The FAME fraction contained only 0.72% (mass basis) FFA and no AG. Of the glycerol released by transesterification, 93% was located in the alcoholic ester phase and 75 was on the post-transesterification flakes.

Key Words

Biodiesel fats and oil utilization fatty acid ester in situ transesterification transesterification 


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  1. 1.
    Basiron, Y., and S. Ahmad, Palm Oil, Coconut Oil and Palm Kernel Oil: Issues and Future Prospects, Proceedings of the 2002 World Oleochemical Conference, April 14–17, 2002. Barcelona, Spain.Google Scholar
  2. 2.
    Kemper, T.G., Solvent Recovery and Loss Management, in Technology and Solvents for Extracting Oilseeds and Nonpetroleum Oils, edited by P.J. Wan and P.J. Wakelyn, AOCS Press, Champaign, IL, 1997, pp. 148–152.Google Scholar
  3. 3.
    National Emission Standards for Hazardous Air Pollutants, Part A, Section 112, U.S. Public Law 101-549, The Clean Air Act Amendments of 1990, 1990, available at Scholar
  4. 4.
    Biodiesel: A Technology, Performance, and Regulatory Overview, National SoyDiesel Development Board, Jefferson City, MO, 1994, p. 3.Google Scholar
  5. 5.
    Harrington, K.J., and C. D'Arcy-Evans, Transesterification in situ of Sunflower Seed Oil, Ind. Eng. Chem. Prod. Res. Dev. 24:314–318 (1985).CrossRefGoogle Scholar
  6. 6.
    Harrington, K.J., and C. D'Acry-Evans, A Comparison of Conventional and in situ Methods of Transesterification of Seed Oil from a Series of Sunflower Cultivars, J. Am. Oil Chem. Soc. 62:1009–1013 (1985).CrossRefGoogle Scholar
  7. 7.
    Siler-Marinkovic, S., and A. Tomasevic, Transesterification of Sunflower Oil in situ, Fuel 77:1389–1391 (1998).CrossRefGoogle Scholar
  8. 8.
    Ozgul, S., and S. Turkay, In situ Esterification of Rice Bran Oil with Methanol and Ethanol, J. Am. Oil Chem. Soc. 70:145–147 (1993).Google Scholar
  9. 9.
    Ozgul-Yucel, S., and S. Turkay, Variables Affecting the Yields of Methyl Esters Derived from in situ Esterification of Rice Bran Oil, Ibid. 79:611–613 (2002).Google Scholar
  10. 10.
    Ozgul-Yucel, S., and S. Turkay, FA Monoalkylesters from Rice Bran Oil by in situ Esterification, Ibid. 80:81–84 (2003).Google Scholar
  11. 11.
    Kildiran, G., S. Ozgul Yucel, and S. Turkay, In situ Alcoholysis of Soybean Oil, Ibid. 73:225–228 (1996).CrossRefGoogle Scholar
  12. 12.
    Freedman, B., E.H. Pryde, and T.L. Mounts, Variables Affecting the Yields of Fatty Esters from Transesterified Vegetable Oils, Ibid. 61:1638–1643 (1984).Google Scholar
  13. 13.
    Williams, M.A., and R.J. Hron, Sr., Obtaining Oils and Fats from Source Materials, in Bailey's Industrial Oil & Fat Products, 5th edn., Vol. 4, edited by Y.H. Hui, John Wiley & Sons, New York, pp. 61–155.Google Scholar
  14. 14.
    Fritz, E., and R.W. Johnson, Raw Materials for Fatty Acids, in Fatty Acids in Industry: Processes, Properties, Derivatives, Applications, edited by R.W. Johnson and E. Fritz, Marcel Dekker, New York, 1989, pp. 1–20.Google Scholar
  15. 15.
    Box, G.E.P., W.G. Hunter, and J.S. Hunter, Statistics for Experimenters, John Wiley & Sons, New York, 1978.Google Scholar
  16. 16.
    SAS/STAT User's guide, Version 8, SAS Institute Inc., Cary, NC, 1999.Google Scholar
  17. 17.
    Instruction Manual, Triglycerides Determination Kit, Sigma-Aldrich, St. Louis, 1996, Procedure No. 320-UA.Google Scholar
  18. 18.
    Haas, M.J., and K.M. Scott, Combined Nonenzymatic-Enzymatic Method for the Synthesis of Simple Alkyl Fatty Acid Esters from Soapstock, J. Am. Oil Chem. Soc. 73:1393–1401 (1996).CrossRefGoogle Scholar
  19. 19.
    Standard Specification for Biodiesel Fuel (B100) Blend Stock for Distillate Fuels, Designation D 6751-02, American Society for Testing and Materials, West Conshohocken, PA, 2002.Google Scholar
  20. 20.
    Haas, M.J., and T.A. Foglia, In situ Production of Fatty Acid Alkyl Esters, U.S. Provisional Patent Application No. 60/369,370, 2002.Google Scholar

Copyright information

© AOCS Press 2004

Authors and Affiliations

  • Michael J. Haas
    • 1
  • Karen M. Scott
    • 1
  • William N. Marmer
    • 1
  • Thomas A. Foglia
    • 1
  1. 1.Agricultural Research Service, Eastern Regional Research CenterU.S. Department of AgricultureWyndmoor

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