Grasas y Aceites, Vol 62, No 3 (2011)

Comparison of geometrical isomerization of unsaturated fatty acids in selected commercially refined oils

M. Tasan
Department of Food Engineering, Agricultural Faculty, Namik Kemal University, Turkey

U. Gecgel
Department of Food Engineering, Agricultural Faculty, Namik Kemal University, Turkey

M. Demirci
Department of Food Engineering, Agricultural Faculty, Namik Kemal University, Turkey


Four different commercially refined vegetable oils were analyzed by capillary gas-liquid chromatography for their trans fatty acid contents. The results obtained showed that the total trans FA contents in refined sunflower, corn, soybean, and hazelnut oils were 0.68 ± 0.41, 0.51 ± 0.24, 1.27 ± 0.57, and 0.26 ± 0.07% of total FA, respectively. The total trans FA comprised isomers of the C18:1, C18:2 and C18:3 FA. Meanwhile, five brands of the refined sunflower oil and two brands of hazelnut oil contained no measurable amounts of total trans C18:3 acids. The total trans C18:2 acid was the predominant trans FA found in the refined sunflower and corn oils, while trans polyunsaturated FAs for the refined soybean oils were found at high levels. However, total trans C18:1 acid was the major trans FA for refined hazelnut oils. The commercially refined vegetable oils with a relatively high total polyunsaturated FA contained considerable amounts of trans polyunsaturated isomers. This study indicates that it is necessary to optimize industrial deodorization, especially the time and temperature, for each different FA composition of oil used.


Degree of isomerization; Deodorization; trans Isomer; Refined vegetable oil

Full Text:



Ackman RG, Hooper SN. 1974. Linolenic acid artifacts from the deodorization of oil. J. Am. Oil Chem. Soc. 51, 42-49. doi:10.1007/BF00000011

AOCS. 1992. Official Methods and Recommended Practices of the American Oil Chemists’ Society, 4th Ed. American Oil Chemists’ Society, Champaign, IL. Method Ce 2-66.

Bruggen PC, Duchateau GSMJE, Mooren MMW, Van Oosten HJ. 1998. Precision of low trans fatty acid level determination in refined oils. Results of a collaborative capillary gas-liquid chromatography study. J. Am. Oil Chem. Soc. 75, 483-488. doi:10.1007/s11746-998-0251-0

De Greyt W, Radanyi O, Kellens M, Huyghebaert A. 1996. Contribution of trans fatty acids from vegetable oils and margarines to the Belgian diet. Fett/Lipid 98, 30-33.

Duchateau GSMJE, Van Oosten HJ, Vasconcellos MA. 1996. Analysis of cis and trans fatty acid isomers in hydrogenated and refined vegetable oils by capillary gas-liquid chromatography. J. Am. Oil Chem. Soc. 73, 275-282. doi:10.1007/BF02523420

Erickson DR. 1995. Overview of modern soybean processing and links between processes. In: Erickson DR (ed.), Practical Handbook of Soybean Processing and Utilization, pp. 62–64, AOCS Press, Champaign.

FDA. 2003. Food and Drug Administration, food labeling: Trans fatty acids in nutrition labeling, nutrient content claims, and health claims. Fed. Regist. 68, 41434-41506.

Ferrari RAP, Schulte E, Esteves W, Bruhl L, Mukherjee KD. 1996. Minor constituents of vegetable oils during industrial processing. J. Am. Oil Chem. Soc. 73, 587-592. doi:10.1007/BF02518112

García JO, Meza NG, Rodríguez JAN, Quiñónez OD, Galindo HSG, Guerrero JOA, Juárez LAM. 2006. Refining of high oleic safflower oil: effect on the sterols and tocopherols content. Eur. Food Res. Technol. 223, 775-779. doi:10.1007/s00217-006-0267-3

Henon G, Kemeny Z, Recseg K, Zwobada F, Kovari K. 1999. Deodorization of vegetable oils. Part I: Modeling the geometrical isomerization of polyunsaturated fatty acids. J. Am. Oil Chem. Soc. 76, 73-81. doi:10.1007/s11746-999-0050-2

Jawad IM, Kochhar SP, Hudson BJF. 1983. Quality characteristics of physically refined soya bean oil: effects of pre-treatment and processing time and temperature. J. Food Technol. 18, 353-360. doi:10.1111/j.1365-2621.1983.tb00278.x

Jung MY, Yoon SH, Min DB 1989. Effects of processing steps on the content of minor compounds and oxidation of soybean oil. J. Am. Oil Chem. Soc. 66, 118-120. doi:10.1007/BF02661798

Karaali A. 1985. The effects of refining on the chemical composition of Turkish sunflower seed oil. Fette Seifen Anstrichmittel 87, 112-117. doi:10.1002/lipi.19850870308

Kellens M. 1997. Current Developments in Oil Refining Technology. Technical Report, pp.35-48, De Smet- Belgium. Antwerp, Belgium.

Kemeny Z, Recseg K, Henon G, Kovari K, Zwobada F. 2001. Deodorization of vegetable oils: Prediction of trans polyunsaturated fatty acid content. J. Am. Oil Chem. Soc. 78, 973-979. doi:10.1007/s11746-001-0374-0

León-Camacho M, Ruíz-Méndez MV, Graciani-Constante E. 1999. Isomerization of fatty acids during deodorization and physical refining-stripping with nitrogen. Fett/Lipid 101, 290-294.

Martin CA, Milinsk MC, Visentainer JV, Matsushita M, De-Souza NE. 2007. Trans fatty acid-forming processes in foods: a review. An. Acad. Bras. Cienc. 79, 343-350. doi:10.1590/S0001-37652007000200015

Martin CA, Visentainer JV, Oliveria AN, Oliveria CC, Matsushita M, De-Souza NE. 2008. Fatty acid contents of Brazilian soybean oils with emphasis on trans fatty acids. J. Brazilian Chem. Soc. 19, 117-122. doi:10.1590/S0103-50532008000100017

Matthaus B, Bruhl L. 2003. Quality of cold-pressed edible rapeseed oil in Germany. Nahrung/Food 47, 413-419.

Mayamol, PN, Samuel T, Balachandran C, Sundaresan A, Arumughan C. 2004. Zero-trans shortening using palm stearin and rice bran oil. J. Am. Oil Chem. Soc. 81, 406-413. doi:10.1007/s11746-004-0914-7

Medina-Juárez LA, Gámez MN, Ortega GJ, Noriega RJA, Angulo GO. 2000. Trans fatty acid composition and tocopherol content in vegetable oils produced in Mexico. J. Am. Oil Chem. Soc. 77, 721-724. doi:10.1007/s11746-000-0116-3

Schwarz W. 2000. Formation of trans polyalkenoic fatty acids during vegetable oil refining. Eur. J. Lipid Sci. Technol. 102, 648-649. doi:10.1002/1438-9312(200010)102:10<648::AID-EJLT648>3.0.CO;2-V

Tasan M, Demirci M. 2003. Trans FA in sunflower oil at different step of refining. J. Am. Oil Chem. Soc. 80, 825-828. doi:10.1007/s11746-003-0779-9

Van Hoed V, Depaemelaere G, Vila Ayala J, Santiwattana P, Verhe R, De Greyt W. 2006. Influence of chemical refining on the major and minor components of rice bran oil. J. Am. Oil Chem. Soc. 83, 315-321. doi:10.1007/s11746-006-1206-y

Wolff RL. 1993. Heat-induced geometrical isomerization of a-linolenic acid: effect of temperature and heating time on the appearance of individual isomers. J. Am. Oil Chem. Soc. 70, 425-430. doi:10.1007/BF02552718

Wolff RL. 1992. Trans-polyunsaturated fatty acid in French edible rapeseed and soybean oils. J. Am. Oil Chem. Soc. 69, 106-110. doi:10.1007/BF02540558

Wolff RL. 1994. Cis-trans isomerization of octadecatrieonic acids during heating. Study of Pinolenic (cis-5, cis-9, cis-12 18:3) acid geometrical isomers in heated pine seed oil. J. Am. Oil Chem. Soc. 71, 1129-1134. doi:10.1007/BF02675907

Zehnder CT. 1995. Deodorization. In: Erickson DR (ed.) Practical Handbook of Soybean Processing and Utilization, pp.240-244, AOCS Press, Champaign.

Copyright (c) 2011 Consejo Superior de Investigaciones Científicas (CSIC)

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Contact us

Technical support