Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish due to the presence of impurities. In chemical terms, oleic acid is classified as a monounsaturatedomega-9 fatty acid, abbreviated with a lipid number of 18:1 cis-9, and a main product of Δ9-desaturase.[2] It has the formula CH3−(CH2)7−CH=CH−(CH2)7−COOH.[3] The name derives from the Latin word oleum, which means oil.[4] It is the most common fatty acid in nature.[5] The salts and esters of oleic acid are called oleates. It is a common component of oils, and thus occurs in many types of food, as well as in soap.
Fatty acids (or their salts) often do not occur as such in biological systems. Instead fatty acids such as oleic acid occur as their esters, commonly triglycerides, which are the greasy materials in many natural oils. Oleic acid is the most common monounsaturated fatty acid in nature. It is found in fats (triglycerides), the phospholipids that make membranes, cholesteryl esters, and wax esters.[6]
Free oleic acid occurs in oils and fats as a product of the breakdown of triglycerides. Olive oil exceeding 2% free oleic acid is graded unfit for human consumption. See Fatty acid §Free fatty acids.[7] It is a chemical signal use by some ants.[14][15][16][17]
Oleic acid is the most abundant fatty acid in human adipose tissue,[18] and second in abundance in human tissues overall, following palmitic acid.
The trans isomer of oleic acid is called elaidic acid or trans-9-octadecenoic acid. These isomers have distinct physical properties and biochemical properties. Elaidic acid, the most abundant trans fatty acid in diet, appears to have an adverse effect on health.[21] A reaction that converts oleic acid to elaidic acid is called elaidinization.
Another naturally occurring isomer of oleic acid is petroselinic acid.
In chemical analysis, fatty acids are separated by gas chromatography of their methyl ester derivatives. Alternatively, separation of unsaturated isomers is possible by argentation thin-layer chromatography.[22]
Safflower and olive oil have one of the highest levels of oleic acid among dietary fats
Oleic acid is used as a component in many foods, in the form of its triglycerides. It is a component of the normal human diet, being a part of animal fats and vegetable oils.[3]
Oleic acid as its sodium salt is a major component of soap as an emulsifying agent. It is also used as an emollient.[53] Small amounts of oleic acid are used as an excipient in pharmaceuticals, and it is used as an emulsifying or solubilizing agent in aerosol products.[54]
Niche uses
Oleic acid is used to induce lung damage in certain types of animals for the purpose of testing new drugs and other means to treat lung diseases. Specifically in sheep, intravenous administration of oleic acid causes acute lung injury with corresponding pulmonary edema.[55]
Oleic acid is used as a soldering flux in stained glass work for joining lead came.[56]
Health effects
Oleic acid is the most common monounsaturated fat in the human diet (~90% of all monounsaturated fats).[57] Monounsaturated fat consumption has been associated with decreased low-density lipoprotein (LDL) cholesterol, and possibly with increased high-density lipoprotein (HDL) cholesterol.[58] Oleic acid may be responsible for the hypotensive (blood pressure reducing) effects of olive oil that is considered a health benefit.[59] A 2017 review found that diets enriched in oleic acid are beneficial for regulating body weight.[60]
The United States FDA has approved a health claim on reduced risk of coronary heart disease for high oleic (> 70% oleic acid) oils.[61] Some oil plants have cultivars bred to increase the amount of oleic acid in the oils. In addition to providing a health claim, the heat stability and shelf life may also be improved, but only if the increase in monounsaturated oleic acid levels correspond to a substantial reduction in polyunsaturated fatty acid (especially α-linolenic acid) content.[62][63] When the saturated fat or trans fat in a fried food is replaced with a stable high oleic oil, consumers may be able to avoid certain health risks associated with consuming saturated fat and trans fat.[64][65]
↑ "9-Octadecenoic acid". PubChem, National Center for Biotechnology Information, US National Library of Medicine. 14 July 2018. Retrieved 19 July 2018.
↑ Villarreal-Lozoya, Jose E.; Lombardini, Leonardo; Cisneros-Zevallos, Luis (2007). "Phytochemical constituents and antioxidant capacity of different pecan Carya illinoinensis (Wangenh.) K. Koch cultivars". Food Chemistry. 102 (4): 1241–1249. doi:10.1016/j.foodchem.2006.07.024.
↑ Moore, K. M.; Knauft, D. A. (1989). "The Inheritance of High Oleic Acid in Peanut". The Journal of Heredity. 80 (3): 252–3. doi:10.1093/oxfordjournals.jhered.a110845.
↑ Nutter, Mary K.; Lockhart, Ernest E.; Harris, Robert S. (1943). "The chemical composition of depot fats in chickens and turkeys". Oil & Soap. 20 (11): 231–4. doi:10.1007/BF02630880. S2CID84893770.
↑ Kokatnur, MG; Oalmann, MC; Johnson, WD; Malcom, GT; Strong, JP (1979). "Fatty acid composition of human adipose tissue from two anatomical sites in a biracial community". The American Journal of Clinical Nutrition. 32 (11): 2198–205. doi:10.1093/ajcn/32.11.2198. PMID495536.
↑ Toledo Hijo, Ariel A. C.; Maximo, Guilherme J.; Costa, Mariana C.; Cunha, Rosiane L.; Pereira, Jorge F. B.; Kurnia, Kiki A.; Batista, Eduardo A. C.; Meirelles, Antonio J. A. (2017). "Phase Behavior and Physical Properties of New Biobased Ionic Liquid Crystals". The Journal of Physical Chemistry B. 121 (14): 3177–3189. doi:10.1021/acs.jpcb.7b01384. PMID28332847.
↑ Breuer, B.; Fock, H. P. (1987). "Separation of fatty acids or methyl esters including positional and geometric isomers by alumina argentation thin-layer chromatography". J. Chromatogr. Sci. 25 (7): 302–306. doi:10.1093/chromsci/25.7.302. PMID3611285.
↑ Marinescu, Smaranda C.; Schrock, Richard R.; Müller, Peter; Hoveyda, Amir H. (2009). "Ethenolysis Reactions Catalyzed by Imido Alkylidene Monoaryloxide Monopyrrolide (MAP) Complexes of Molybdenum". J. Am. Chem. Soc. 131 (31): 10840–10841. doi:10.1021/ja904786y. PMID19618951.
1 2 3 "FoodData Central". United States Department of Agriculture. 1 April 2019. All values in this table are from this database unless otherwise cited or when italicized as the simple arithmetic sum of other component columns.
1 2 3 4 Katragadda, Harinageswara Rao; Fullana, Andrés; Sidhu, Sukh; Carbonell-Barrachina, Ángel A. (May 2010). "Emissions of volatile aldehydes from heated cooking oils". Food Chemistry. 120 (1): 59–65. doi:10.1016/j.foodchem.2009.09.070.
↑ "Canola oil, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
↑ "Coconut oil, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
↑ "Palm oil, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
↑ Aladedunye, Felix; Przybylski, Roman (December 2013). "Frying stability of high oleic sunflower oils as affected by composition of tocopherol isomers and linoleic acid content". Food Chemistry. 141 (3): 2373–2378. doi:10.1016/j.foodchem.2013.05.061. PMID23870970.
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