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Lipid peroxidation, or lipid oxidation, is a complex chemical process that leads to oxidative degradation of lipids, [1] resulting in the formation of peroxide and hydroperoxide derivatives. [2] It occurs when free radicals , specifically reactive oxygen species (ROS), interact with lipids within cell membranes , typically polyunsaturated fatty ...
It is well known that fats, especially polyunsaturated fats, become rancid, even when kept at low temperatures, [19] however many other foods are susceptible to autoxidation. The complex mixture of compounds found in wine, including polyphenols , polysaccharides, and proteins, can undergo autoxidation during the aging process, leading to wine ...
Physiological antioxidants are classified into two broad divisions, depending on whether they are soluble in water (hydrophilic) or in lipids . In general, water-soluble antioxidants react with oxidants in the cell cytosol and the blood plasma, while lipid-soluble antioxidants protect cell membranes from lipid peroxidation. [32]
The natural antioxidants tend to be short-lived, [13] so synthetic antioxidants are used when a longer shelf-life is preferred. The effectiveness of water-soluble antioxidants is limited in preventing direct oxidation within fats, but is valuable in intercepting free radicals that travel through the aqueous parts of foods. A combination of ...
Glutathione peroxidase 4 (GPx4) has a high preference for lipid hydroperoxides; it is expressed in nearly every mammalian cell, though at much lower levels. Glutathione peroxidase 2 is an intestinal and extracellular enzyme, while glutathione peroxidase 3 is extracellular, especially abundant in plasma. [ 4 ]
Alpha-tocopherol is a fat-soluble antioxidant functioning within the glutathione peroxidase pathway, [15] and protecting cell membranes from oxidation by reacting with lipid radicals produced in the lipid peroxidation chain reaction. [3] [16] This removes the free radical intermediates and prevents the oxidation reaction from continuing.
4-Hydroxynonenal, or 4-hydroxy-2E-nonenal or 4-hydroxy-2-nonenal or 4-HNE or HNE, (C 9 H 16 O 2), is an α,β-unsaturated hydroxyalkenal that is produced by lipid peroxidation in cells. 4-HNE is the primary α,β-unsaturated hydroxyalkenal formed in this process. It is a colorless oil.
Lipid peroxidation is considered to be a major reason for the deterioration of quality of meat products (rancidity and unappetizing flavors). [19] Sodium nitrite acts as an antioxidant in a mechanism similar to the one responsible for the coloring effect. [ 19 ]