Abstract
Oil was extracted from soybeans, degummed, alkalirefined and bleached. The oil was heated at 160, 180, 200, 220 and 240°C for up to 156 h. Fatty acid methyl esters were prepared by boron trifluoride-catalyzed transesterification. Gas-liquid chromatography with a cyanopropyl CPSil88 column was used to separate and quantitate fatty acid methyl esters. Fatty acids were identified by comparison of retention times with standards and were calculated as area % and mg/g oil based on 17:0 internal standard. The rates of 18:3ω3 loss and 18:3 Δ9-cis, Δ12-cis, Δ15-trans (18:3c,c,t) formation were determined, and the activation energies were calculated from Arrhenius plots. Freshly prepared soy oil had 10.1% 18:3ω3 and no detectable 18:3c,c,t. Loss of 18:3ω3 followed apparent first-order kinetics. The first-order rate constants ranged from .0018±.00014 min−1 at 160°C to .083±.0033 min−1 at 240°C. The formation of 18:3c,c,t did not follow simple kinetics, and initial rates were estimated. The initial rates (mg per g oil per h) of 18:3c,c,t formation ranged from 0.0031±0.0006 at 160°C to 2.4±.24 at 240°C. The Arrhenius activation energy for 18:3ω3 loss was 82.1±7.2 kJ mol−1. The apparent Arrhenius activation energy for 18:3c,c,t formation was 146.0±13.0 kJ mol−1. The results indicate that small differences in heating temperature can have a profound affect on 18:3c,c,t formation. Selection of appropriate deodorization conditions could limit the amount of 18:3c,c,t produced.
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References
Ackman, R.G., S.N. Hooper and D.L. Hooper,J. Am. Oil Chem. Soc. 51:42 (1974).
Grandgirard, A., J.L. Sebedio and J. Fleury, Ibid.:1563 (1984).
Wolff, R.L., Ibid.:106 (1992).
Wolff, R.L., and J.L. Sebedio, Ibid.:719 (1991).
Ratnayake, W.M.N., R. Hollywood and E. O’Grady,Can. Inst. Food Sci. Technol. J. 24:81 (1991).
Ratnayake, W.M.N., and J.L. Beare-Rogers,J. Chromatogr. Sci. 28:633 (1990).
Ratnayake, W.M.N., R. Hollywood, E. O’Grady and J.L. Beare-Rogers,J. Am. Oil Chem. Soc. 67:804 (1990).
O’Keefe, S.F., S. Gaskins and V.A. Wiley,Food Res. International, in press (1993).
Sebedio, J.L., A. Grandgirard, C. Septier and J. Prevost,Rev. Fr. Corps Gras 34:15 (1987).
Perkins, E.G., and C. Smick,J. Am. Oil Chem. Soc. 64:1150 (1987).
Piconneaux, A., A. Grandgirard and J.L. Sebedio,C.R. Acad. Sc. Paris 300:353 (1985).
Grandgirard, A., A. Piconneaux, J.L. Sebedio, S.F. O’Keefe, E. Semon and J.L. LeQuere,Lipids 24:799 (1989).
O’Keefe, S.F., M. Lagarde, A. Grandgirard and J.L. Sebedio,J. Lipid Res. 31:1241 (1990).
Grandgirard, A., and F. Juilliard,Rev. Fr. Corps Gras 34:213 (1987).
International Union of Pure and Applied Chemistry, Oxford, 1982, Method No. 2.201.
Morrison, W.R., and L.M. Smith,J. Lipid Res. 5:600 (1964).
Wolff, R.L.,J. Chromatogr. Sci. 30:17 (1992).
Price, N.C., and R.A. Dwek,Principles and Problems in Physical Chemistry for Biochemists, Oxford University Press, Oxford, 1973.
Villota, R., and J.G. Hawkes, inHandbook of Food Engineering, edited by D.R. Heldman, and D.B. Lund, Marcel Dekker Inc, New York, 1992, p. 41.
Brekke, O.L., inHandbook of Soy Oil Processing and Utilization, edited by D.R. Erickson, E.H. Pryde, O.L. Brekke, T.L. Mounts and R.A. Falb, American Oil Chemists’ Society, Champaign, 1980, pp. 155–192.
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O’Keefe, S.F., Wiley, V.A. & Wright, D. Effect of temperature on linolenic acid loss and 18:3 Δ9-cis, Δ12-cis, Δ15-trans formation in soybean oil. J Am Oil Chem Soc 70, 915–917 (1993). https://doi.org/10.1007/BF02545354
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DOI: https://doi.org/10.1007/BF02545354