| Vegetable oil,which is rich in unsaturated fatty acids and micronutrients,plays an important role in daily diet.While with high-fat intake,it is easy to be overweight and be victim of some diseases like hypertension or hyperlipidemia.The fatty acid composition and contents of micronutrients vary according to the type of vegetable oils.The choice of edible vegetable oil will affect people's nutritional balance and safety to some degree.Therefore,the physicochemical properties,oxidative stability and effects on lipid metabolism in high-fat diet SD rats of different kinds of edible vegetable oils in Chinese market were studied to provide the foundation for quality,nutrition and safety evaluation of domestic vegetable oils and reasonable reference for consumers.Firstly,Soybean oil,rapeseed oil,corn oil,sunflower seed oil,rice bran oil,peanut oil and tea seed oil were studied on different physicochemical properties.The results showed that the content of unsaturated fatty acids of the 7 kinds of oils were all relatively high(78.42% ~ 92.24%),however,the compositions of fatty acid were different in different oils.The tea seed oil,sunflower seed oil and rapeseed oil had the highest content of monounsaturated fatty acid(80.68%),polyunsaturated fatty acids(61.18%)and unsaturated fatty acids(92.24%),respectively.The content of total phenols was the highest in rapeseed oil,reaching 139.83 mg GAE/kg.The main isomers of tocopherols in vegetable oils were ?-tocopherol and ?-tocopherol.The tocopherols content was the highest in soybean oil(1129.21 mg/kg).The main phytosterols was ?-sitosterol in vegetable oils and the content of phytosterols was relatively higher in rice bran oil(10705.8 mg/kg)and corn oil(8596.7 mg/kg).Benzo(a)pyrene and aflatoxin B1 were detected from few oil samples and the contents were all lower than the standards.The content of 3-MCPD ester was relatively low in rapeseed,sunflower seed,soybean and peanut oils(lower than 1.0 mg/kg).Secondly,the oxidative stability of different vegetable oils was studied based on the oxidative stability index(OSI)and scavenging capacity for DPPH radicals.The results showed that the oxidative stability was linked to the contents of micronutrients.It proved that OSI was significantly related to the content of total phenols.And the partial correlation analysis showed a positive relation between OSI,scavenging capacity for DPPH radicals and the contents of tocopherols and phytosterols.Finally,the effects on lipid metabolism of different vegetable oils were studied by highfat fed SD rats.Lipid profile,redox indicators in serum and liver,hepatic histopathological examination,fatty acid composition in hepar and hepatic lipid metabolism related-genes relative expression were detected after twelve-week high-fat diet.According to the results,vegetable oils decreased the liver lipid metabolism disorder compared with high fat group which was rich in saturated fatty acids.Tea seed oil(79.59% C18:1)and rapeseed oil(63.66% C18:1)groups which are rich in monounsaturated fatty acid especially Oleic acid(C18:1)could significantly reduce TC,LDL-C contents in serum,atherosclerosis index(AI),MDA content,and increase SOD level to improve the antioxidant capacity.Histopathological examination result indicated that the tea seed oil,rapeseed oil,rice bran oil and peanut oil could protect the liver cell damage induced by high-fat diet and reduce hepatic fat deposition to some extent.The hepatic fatty acid composition like the contents of oleic acid(C18:1),linoleic acid(C18:2)and ?-linolenic acid(C18:3n3)were positively correlated with the fatty acid composition in the food intake,and the correlation coefficient were 0.643,0.772 and 0.915,respectively.Hepatic lipid metabolism related-genes relative expression may result from high-fat diet.Compared with high fat group,tea seed oil,rapeseed oil and rice bran oil could increase the expression of PPAR? and Acox1 to decrease lipid metabolism disorders. |
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