ABSTRACT
I. Introduction.......................................................................................................................... 449 II. Mechanisms of Lipid Autoxidation..................................................................................... 449 III. Mechanisms of Photosensitized Oxidation of Lipids.......................................................... 453 IV. Effects of Minor Compounds in Oil on the Lipid Oxidation.............................................. 455
A. Free Fatty Acids........................................................................................................... 455 B. Mono-and Diacylglycerols.......................................................................................... 457 C. Metals ........................................................................................................................... 457 D. Phospholipids ............................................................................................................... 458 E. Thermally Oxidized Compounds and Hydroperoxides ............................................... 459 F. Chlorophylls................................................................................................................. 459 G. Carotenoids .................................................................................................................. 460 H. Tocopherols and Tocotrienols ..................................................................................... 461 I. Other Phenolic Compounds......................................................................................... 464 J. Antioxidant Interactions............................................................................................... 467
References ..................................................................................................................................... 467
Lipid oxidation produces low molecular weight off-flavor compounds and affects the quality and shelf life of foods [1]. The off-flavor compounds decrease the consumer acceptability or industrial use of lipid as a food ingredient. Lipid oxidation destroys essential fatty acids and produces toxic compounds and oxidized polymers [2]. Lipid oxidation is influenced by many factors: energy input such as light or heat, food composition, types of oxygen, and minor compounds such as free fatty acids, mono-and diacylglycerols, metals, peroxides, thermally oxidized compounds, chlorophylls, carotenoids, tocopherols (TOH), and other phenolic compounds. Some of them accelerate the oil oxidation and others act as antioxidants. The major mechanisms of lipid oxidation during food processing and storage are autoxidation and photosensitized oxidation. The improvement of oxidative stability of lipid foods can be achieved by thorough understanding of chemical mechanisms of lipid oxidation and functions of some compounds present in oil, naturally or added on purpose, other than triacylglycerols.
