Linoleic acid, antioxidant action

Vulcain, E. et al. (2005). Inhibition of the metmyoglobin-induced peroxidation of linoleic acid by dietary antioxidants Action in the aqueous vs. lipid phase. Free Rad. Res. 39(5) 547-563. 

These results suggest that the presence in the diet of unsaturated fats increase tocopherol requirements to 10 to 100 times the amounts required in their absence. In the prevention of encephalomalacia in chicks it appears that the role of tocopherol is to act as an antioxidant specifically related to linoleic acid metabolism (Scott, 1962). Whether such specificity of action can explain the results obtained with ruminants seems doubtful, in view of the low linoleic acid content of highly unsaturated fraction of cod liver oil. 

In summary, the relative activities of various antioxidants vary widely according to the site of action in different systems, the charge and solubility of components in micelle compared to emulsions, liposome systems and solutions (Table 10.16). The interfacial behavior of antioxidants varies between bulk oil and different colloidal lipid systems. For example, polar antioxidants such as Trolox are more active in mixed micelle systems consisting of emulsifiers and free fatty acids than in corn oil-in-water emulsions, where they partition mainly in the water phase (see next Section). Although linoleic acid is commonly used... 

Soon after harvest, tree nuts, because of their high concentrations of unsaturated fatty acids, may undergo development of oxidative rancidity. This leads to the formation of undesirable rancid flavors and a decline in both unsaturated fatty acids (e.g., oleic, linoleic, and linolenic acids) and natural antioxidants (e.g., tocopherols) [63]. The postharvest stability and sensory quality of tree nuts are influenced by several factors such as chemical composition (e.g., fatty acid composition and presence of antioxidants such as tocopherols), moisture content, oxygen concentration, and temperature, among others. There is some evidence that lipid oxidation is at least in part due to the action of oxidative enzymes, such as lipoxygenases. This is supported by the fact that mild to moderate heat treatment of some nuts, such as pecan, retards the development of rancid flavors during storage [64,65]. Nevertheless, mild oxidation is probably necessary for the development of the characteristic volatile flavor components of natural tree nuts [63], In addition to the Upid oxidation volatiles, some other compounds, such as terpenes, lactones, and short-chain volatile acids, may impact the aroma profiles of some types of natural flee nuts. 

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