Frying temperatures and minor constituents of oils and fats
Two important classes of minor constituents of oils and fats are tocopherols and sterols. Both these classes are biologically active and they also affect the stability and performance of an oil at elevated temperatures. Tocopherols are phenolic antioxidants that react with free radicals and their c...
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Consejo Superior de Investigaciones Científicas
1998-08-01
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| Series: | Grasas y Aceites |
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| Online Access: | https://grasasyaceites.revistas.csic.es/index.php/grasasyaceites/article/view/734 |
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| author | Dimitrios Boskou |
| author_facet | Dimitrios Boskou |
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| collection | DOAJ |
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Two important classes of minor constituents of oils and fats are tocopherols and sterols. Both these classes are biologically active and they also affect the stability and performance of an oil at elevated temperatures. Tocopherols are phenolic antioxidants that react with free radicals and their concentration is reduced signifantly when the oil is heated. α-TocopheroI is lost faster during deep-fat frying than the beta, gamma and delta homologues. In the presence of stronger antioxidants, natural or synthetic, losses of α-tocopherol can be eliminated. Unchanged phytosterols naturally present in vegetable oils are believed to be beneficial for the health. Depending on the chemical structure, phytosterols may act as prooxidants or antioxidants. Sterols with an ethylidene group in the side chain have been found effective in retarding polymerisation at temperatures similar to those of deep-fat frying. Under unfavourable conditions (high temperature, presence of air) oxidation products are formed from sterols and a marked increase in the oxidation rate of the fat is observed. Oxidation products of the main phytosterols, β-sitosterol and stigmasterol, are: hydrocarbons (3,5-diene and 3,5,22-triene), mono-, di- and triunsaturated ketosteroids (4-en-3-one, 3,5-dien-7-one, 3,5,22-trien-7-one), 5,6-epoxy derivatives, 3,7-diols and pregnane derivatives. Other minor constituents which may affect the rate of degradation of unsaturated triacylglycerols at high temperatures are squalene, pigments and phospholipids. Squalene and phospholipids have both been reported to retard the degradation of unsaturated fatty acids under simulated frying conditions. High chlorophyll levels were found to increase the rate of tocopherol decomposition and formation of polymers in rape seed oil heated at 180°C.
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| format | Article |
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| institution | DOAJ |
| issn | 0017-3495 1988-4214 |
| language | English |
| publishDate | 1998-08-01 |
| publisher | Consejo Superior de Investigaciones Científicas |
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| series | Grasas y Aceites |
| spelling | doaj-art-799499bc2163414e890083f4f2ddc4cc2025-08-20T03:10:58ZengConsejo Superior de Investigaciones CientíficasGrasas y Aceites0017-34951988-42141998-08-01493-410.3989/gya.1998.v49.i3-4.734724Frying temperatures and minor constituents of oils and fatsDimitrios Boskou0Faculty of Chemistry, Aristotle University Two important classes of minor constituents of oils and fats are tocopherols and sterols. Both these classes are biologically active and they also affect the stability and performance of an oil at elevated temperatures. Tocopherols are phenolic antioxidants that react with free radicals and their concentration is reduced signifantly when the oil is heated. α-TocopheroI is lost faster during deep-fat frying than the beta, gamma and delta homologues. In the presence of stronger antioxidants, natural or synthetic, losses of α-tocopherol can be eliminated. Unchanged phytosterols naturally present in vegetable oils are believed to be beneficial for the health. Depending on the chemical structure, phytosterols may act as prooxidants or antioxidants. Sterols with an ethylidene group in the side chain have been found effective in retarding polymerisation at temperatures similar to those of deep-fat frying. Under unfavourable conditions (high temperature, presence of air) oxidation products are formed from sterols and a marked increase in the oxidation rate of the fat is observed. Oxidation products of the main phytosterols, β-sitosterol and stigmasterol, are: hydrocarbons (3,5-diene and 3,5,22-triene), mono-, di- and triunsaturated ketosteroids (4-en-3-one, 3,5-dien-7-one, 3,5,22-trien-7-one), 5,6-epoxy derivatives, 3,7-diols and pregnane derivatives. Other minor constituents which may affect the rate of degradation of unsaturated triacylglycerols at high temperatures are squalene, pigments and phospholipids. Squalene and phospholipids have both been reported to retard the degradation of unsaturated fatty acids under simulated frying conditions. High chlorophyll levels were found to increase the rate of tocopherol decomposition and formation of polymers in rape seed oil heated at 180°C. https://grasasyaceites.revistas.csic.es/index.php/grasasyaceites/article/view/734Heated fatsMinor constituentsSterolsTocopherols |
| spellingShingle | Dimitrios Boskou Frying temperatures and minor constituents of oils and fats Grasas y Aceites Heated fats Minor constituents Sterols Tocopherols |
| title | Frying temperatures and minor constituents of oils and fats |
| title_full | Frying temperatures and minor constituents of oils and fats |
| title_fullStr | Frying temperatures and minor constituents of oils and fats |
| title_full_unstemmed | Frying temperatures and minor constituents of oils and fats |
| title_short | Frying temperatures and minor constituents of oils and fats |
| title_sort | frying temperatures and minor constituents of oils and fats |
| topic | Heated fats Minor constituents Sterols Tocopherols |
| url | https://grasasyaceites.revistas.csic.es/index.php/grasasyaceites/article/view/734 |
| work_keys_str_mv | AT dimitriosboskou fryingtemperaturesandminorconstituentsofoilsandfats |