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Antioxidant Evaluation and Oxidative Stability of Structured Lipids from Extravirgin Olive Oil and Conjugated Linoleic Acid

Lee, J.H., Lee, K.T., Akoh, C.C., Chung, S.K., Kim, M.R.
Journal of agricultural and food chemistry 2006 v.54 no.15 pp. 5416-5421
olive oil, conjugated linoleic acid, structured lipids, antioxidants, antioxidant activity, oxidative stability, isomers, lipid composition, phenolic compounds, tocopherols, rosemary, plant extracts, free radical scavengers
Structured lipid (SL) was synthesized from extravirgin olive oil (EVOO) and conjugated linoleic acid (CLA) via a lipase-catalyzed reaction. CLA provides a variety of health benefits, but it is not consumed in free fatty acid form. The synthesized SL olive oil contained 42.5 mol % CLA isomers, and the major isomers were cis-9,trans-11-CLA (16.9 mol %) and trans-10,cis-12-CLA (24.2 mol %). The antioxidant activity determined by the radical scavenging capacity with the 2,2-diphenyl-1-picrylhydrazyl radical was lower in SL olive oil than in EVOO. The oxidative stability was also lower in SL olive oil since it had a higher peroxide value, -anisidine value, and 2-thiobarbituric acid reactive substances values during 20 days of storage at 60°C. This observation could be due to the reduction in the natural phenolic compounds (97%) and tocopherols (56%), and the incorporated CLA with two conjugated double bonds in the SL olive oil. The oxidative stability of SL olive oil was increased by added rosemary extracts at concentrations of 100, 200, and 300 ppm. The present study suggests that the SL olive oil may be a suitable way to incorporate or deliver CLA into human diets. However, the addition of a proper antioxidant would be required for improving its oxidative stability.