Journal of the American Oil Chemists' Society

, Volume 79, Issue 3, pp 225–230

Characterization and supercritical carbon dioxide extraction of walnut oil

  • Rui Oliveira
  • M. Fátima Rodrigues
  • M. Gabriela Bernardo-Gil
Article

Abstract

Walnut (Juglans regia L.) oil was extracted with compressed carbon dioxide (CO2) in the temperature range of 308 to 321 K and in the pressure range of 18 to 23.4 MPa. The influence of particle size was also studied at a superficial velocity of 0.068 cm/s, within a tubular extractor of 0.2 L capacity (cross-sectional area of 16.4 cm2). FFA, sterol, TAG, and tocopherol compositions were not different from those of oil obtained with n-hexane. The main FA was linoleic acid (56.5%), followed by oleic acid (21.2%) and linolenic acid (13.2%). The main TAG was LLL (linoleic, linoleic, linoleic) (24.4%), followed by OLL (oleic, linoleic, linoleic) (19.6%) and LLLn (linoleic, linoleic, linolenic) (18.4%). The main component of sterols was β-sitosterol (85.16%), followed by campesterol (5.06%). The amount of cholesterol was low (0.31 and 0.16% for oils extracted by n-hexane and supercritical fluid extraction, respectively. The CO2-extracted oil presented a larger amount of tocopherols (405.7 μg/g oil) when compared with 303.2 μg/g oil obtained with n-hexane. Oxidative stability determined by PV and the Rancimat method revealed that walnut oil was readily oxidized. Oil extracted by supercritical CO2 was clearer than that extracted by n-hexane, showing some refining. A central composite, nonfactorial design was used to optimize the extraction conditions using the software Statistica, Version 5. The best results were found at 22 MPa, 308 K, and particle diameter (Dp) −0.1 mm.

Key Words

Juglans regia L. lipids oil characterization supercritical CO2 walnut 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Rattray, J.B., Spring: A New Beginning, inform 11:303–311 (2000).Google Scholar
  2. 2.
    Rockland, L.B., and C. De Benedict, Occurrence of Fatty Acid Methyl Esters in Walnut Kernel and Other Oils, J. Agric. Food Chem. 18:228–233 (1970).CrossRefGoogle Scholar
  3. 3.
    Greve, C., G. McGranahan, J. Hansey, R. Snyder, K. Kelly, D. Goldhamerer, and J. Labavitch, Variation in Polyunsaturated Fatty Acid Composition of Persian Walnut. J. Soc. Hort. Sci. 117:518–522 (1992).Google Scholar
  4. 4.
    Savage, G.P., P.C. Dutta, and D.L. McNeil, Fatty Acid and Tocopherol Contents and Oxidative Stability of Walnut Oils, J. Am. Oil Chem. Soc. 76:1059–1063 (1999).Google Scholar
  5. 5.
    Zwarts, L., G.P. Savage, and D.L. McNeil, Fatty Acid of New Zealand-Grown Walnuts (Juglans regia L.), Int. J. Food Sci. Nutr. 50:189–194 (1999).CrossRefGoogle Scholar
  6. 6.
    Horrobin, D., and M. Manku, How Do Polyunsaturated Fatty Acids Lower Plasma Cholesterol Levels? Lipids 18:558–562 (1983).CrossRefGoogle Scholar
  7. 7.
    Sabaté, J., G.E. Fraser, K. Burke, S.F. Knutsen, H. Bennet, and K.D. Linstead, Effects of Walnuts on Serum Lipid Levels and Blood Pressure in Normal Men, New Engl. J. Med. 329:603–607 (1993).CrossRefGoogle Scholar
  8. 8.
    Abbey, M., M. Noakes, G.B. Belling, and P.J. Nestel Partial Replacement of Saturated Fatty Acids with Almonds or Walnuts Lowers Total Plasma Cholesterol and Low-Density-Lipoprotein Cholesterol, Am. J. Clin. Nutr. 59:995–999 (1994).Google Scholar
  9. 9.
    Chisholm, A., J. Mann, M. Skeaff, C. Frampton, W. Sutherland, A. Duncan, and S. Tiszavari, A Diet Rich in Walnuts Favourably Influences Plasma Fatty Acid Profile in Moderately Hyperlipidaemic Subjects, Eur. J. Clin. Nutr. 52:12–16 (1998).CrossRefGoogle Scholar
  10. 10.
    Lavedrine, F., D. Zmirou, A. Ravel, F. Balducci, and J. Alary, Blood Cholesterol and Walnut Consumption: A Cross-Sectional Survey in France, Prev. Med. 28:333–339 (1999).CrossRefGoogle Scholar
  11. 11.
    Zambon, D., J. Sabaté, S. Munoz, B. Campero, E. Casals, M. Merlos, J.C. Laguna, and E. Ros, Substituting Walnuts for Monounsaturated Fat Improves the Serum Lipid Profile of Hypercholesterolemic Men and Women. A Randomized Crossover Trial, Ann. Intern. Med. 132:538–546 (2000).Google Scholar
  12. 12.
    Dakovic, S., J. Turkulov, and E. Dimic, The Quality of Vegetable Oils Got by Extraction with CO2, Fat Sci. Technol. 91: 116–119 (1989).Google Scholar
  13. 13.
    Fors, S.M., and C.E. Eriksson, Characterization of Oils Extracted from Oats by Supercritical Carbon Dioxide, Lebensm. Wiss. Technol. 23:390–395 (1990).Google Scholar
  14. 14.
    Esquível, M., and M.G. Bernardo-Gil, Extraction of Olive Husk Oil with Compressed Carbon Dioxide, J. Supercrit. Fluids 6: 91–94 (1993).CrossRefGoogle Scholar
  15. 15.
    Gómez, M.A., C.P. López, and E. Martínez de la Ossa, Recovery of Grape Seed Oil by Liquid and Supercritical Carbon Dioxide: A Comparison with Conventional Solvent Extraction, Chem. Eng. J. 61:227–231 (1996).Google Scholar
  16. 16.
    Kuk, M.S., and M.K. Dowd, Supercritical CO2 Extraction of Rice Bran, J. Am. Oil Chem. Soc. 75:623–628 (1998).Google Scholar
  17. 17.
    Devittori, C., D. Gumy, A. Kusy, L. Colarow, C. Bertoli, and P. Lambelet, Supercritical Fluid Extraction of Oil from Millet Bran, J. Am. Oil Chem. Soc. 77:573–579 (2000).Google Scholar
  18. 18.
    Gómez, M.A., and E. Martínez de la Ossa, Quality of Wheat Germ Oil Extracted by Liquid and Supercritical Carbon Dioxide, J. Am. Oil Chem. Soc. 77:969–974 (2000).Google Scholar
  19. 19.
    Bernardo-Gil, M.G., C. Oneto, A. Antunes, M.F. Rodrigues, and J.M. Empis, Extraction of Lipids from Cherry Seed Oil by Supercritical Carbon Dioxide, Eur. Food Res. Technol. 212: 170–174 (2001).CrossRefGoogle Scholar
  20. 20.
    Official Journal of the European Communities L248:15–22 (1991).Google Scholar
  21. 21.
    Lavedrine, F., A. Ravel, A. Poupard, and J. Alary, Effect of Geographic Origin, Variety and Storage on Tocopherol Concentrations in Walnuts by HPLC, Food Chem. 58:135–140 (1997).CrossRefGoogle Scholar

Copyright information

© AOCS Press 2002

Authors and Affiliations

  • Rui Oliveira
    • 1
  • M. Fátima Rodrigues
    • 1
  • M. Gabriela Bernardo-Gil
    • 1
  1. 1.Centre for Biological and Chemical Engineering, Departmento de Engenharia QuímicaInstituto Superior TécnicoLisbonPortugal

Personalised recommendations