The Effect of Refining Process on the Conjugated Dienes in Soybean Oil

Authors
1 Department of Food Science and Technology, Faculty of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran, Islamic Republic of Iran.
2 Department of Animal Science, Faculty of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran, Islamic Republic of Iran.
3 Technical Manager, Olive Oil Section, Techno Azma Laboratory, Adl Blvd, Poonak Sq., Tehran, Islamic Republic of Iran.
Abstract
The present study was carried out to investigate the effect of various refining processes’ conditions on conjugated dienes in soybean oil. Conjugated dienes contents of soybean oil were found to undergo reduction in neutralization and bleaching steps while being increased in deodorization. It was observed that alkali refining (neutralization) through 12 and 14 °Bé, bleaching with either acid activated clay or a mixture of acid activated clay plus activated carbon at 110˚C along with deodorization at 220˚C and at 4 or 8 mbar had the highest effect on reduction of conjugated dienes in soybean oil. Conjugated dienes were in good correlation with peroxide value, free fatty acids, Totox value and as well with p-anisidine value in each step. Overall, alkali refining proved to be the most effective step in reduction of conjugated dienes, free fatty acids and oxidative stability index. Peroxide value, p-anisidine and Totox values changed during refining and got significantly decreased in deodorization.

Keywords


1. Boskou, D., 2008, Olive oil minor constituents and health. CRC Press, Boca Raton, FL.
2. Chow, C.H.K., 2007, Fatty acids in foods and their health implications. CRC Press, Boca Raton, FL.
3. Codex Standard, Recommended International Code of Practice for Storage and Transport of Edible Fats and Oils in Bulk CAC/RCP 36-1987 (Rev.3-2005)
4. Crapiste, G.H., Brevedan, M.I.V., Carelli, A.A., 1999, Oxidation of sunflower during storage. J. Am. Oil. Chem. Soc, 77, 1437-1443
5. Deman, J.M., 1999, Principle of Food Chemistry. An Aspen publication, Maryland.
6. Dutton, H.J., 1995, Historical glimpses of analytical and quality assessment method for fats and oils. Smouse, T.H., 1995, Factors affecting oil quality and stability. White, P.J., 1995, Conjugated dienes, anisidine value and carbonyl value analysis. In: Warner, K. & Eskin, N.A.M. (eds), Methods to assess quality and stability of oils and fat-containing foods. AOCS Press, Champaign, IL 159-178
7. Farhoosh, R., Einafshar, S., Sharayei, P., 2009, The effect of commercial refining steps on the rancidity measures of soybean and canola oils. Food Chem, 115, 933-938
8. Farhoosh, R., Pazhouhanmehr, S., 2008, Relative contribution of compositional parameters to the primary and secondary oxidation of canola oil. Food Chem, 114, 1002-1006
9. Farhoosh, R., Tavakoli, J., Hadad Khodaparast, M.H., 2008, Chemical composition and oxidative stability of kernel oils from two current subs species of Pistacia Atlantica in Iran. J. Am. Oil. Chem. Soc, 85, 723-729
10. Firestone, D., 1994, Official methods and recommended practices of the American Oil Chemists’Society. AOCS Press, Champaign, IL
11. Gómez-Alonso, S., Salvador, M.D., Fregapane, G., 2004, Evolution of the oxidation process in olive oil triacylglycerol under accelerated storage conditions (40-60˚C). J. Am. Oil. Chem. Soc, 81, 177-184
12. Hamilton, R.J., Kalu, C., McNail, G.P., Padley, F.B., Pierce, J.H., 1998, Effects of tocopherols, ascorbyl palmitate and lecithin on autoxidation of fish oil. J. Am. Oil. Chem. Soc, 75, 813-822
13. Hopia, A., 1993, Analysis of high molecular weight autoxidation products using high performance size exclusion chromatography: ΙΙ Changes During Processing. J. Lebensm-Wiss Technol., 26, 568-571
14. Houhoula, D.P., Oreopoulou, V., Tzia, C., 2002, A kinetic study of oil deterioration during frying and a comparison with heating. J. Am. Oil. Chem. Soc, 79, 133-137
15. O’Brien, R.D., 2004, Fats and oils formulating and processing for application. CRC press,Boca Raton,FL.
16. Oštrić-Matijašević, B., Turkulov, J., Karlović, D., 1979, Quality of sunflower oil bleached during deodorization. J. Am. Oil. Chem. Soc, 57, 323-325
17. Pokorný, J., Schmidt, S., Parkányiová, J., 2005, Ultraviolet-visible spectrophotometry in the analysis of lipid oxidation. In:Pokorný, J. & Kamal-Eldin, A. (eds), Analysis of lipid oxidation. AOCS Press, Champaign, IL, 17-39
18. Taylor, D.R., 2005, Bleaching. In: Shahidi, F. (ed), Bailey’s Industrial Oil and Fat Products. John Wiley and Sons Publication , Hoboken,NJ, 285-339