Rape is the third largest vegetable oil source in the world after soybean and palm, and the largest domestic vegetable oil source in China at present. Low erucic acid rapeseed oil is rich in monounsaturated fatty acids (oleic acid) and n-3 fatty acids (α - linolenic acid). It plays a good role in preventing and reducing cardiovascular and cerebrovascular diseases. It is a healthy edible vegetable oil, which is widely used in the Yangtze River Basin and other places in China. After in-depth analysis of rapeseed oil, experts found that there are more rare healthy trace active ingredients in rapeseed oil, such as phenol, phytosterol, natural vitamin β - caroteneluteinEtc. The polyphenol content of rapeseed oil is higher than that of main bulk vegetable oil, the content of natural vitamin E is second only to soybean oil and corn oil, and the content of phytosterol is second only to corn oil. The content of total phenol in rapeseed oil ranges from 9 to 104 mg/100g, most of which range from 15 to 65 mg/100g. The average content of total phenol in samples from the upper, middle and lower reaches of the Yangtze River is 43, 35 and 29 mg/100g respectively.
Phytosterol can inhibit the absorption of cholesterol in the body, so it has the function of reducing blood cholesterol level. The main phytosterols in rapeseed oil include rapeseed sterolsRapeseed sterol、β - sitosterol, stigmasterol and oat sterol. The content of phytosterol ranges from 432 to 1190 mg/100g. The average content of rapeseed oil in the upper, middle and lower reaches of the Yangtze River is 786, 863 and 830 mg/100g respectively.
In addition, the average content of β - carotene in rapeseed oil is 2.4 mg/kg, and the content of lutein ranges from 28 to 352 mg/kg.
Polyphenols widely exist in plants and are the main secondary metabolites. They have a variety of pharmacological and health effects, such as high-efficiency antioxidant, anti radiation, anti mutagenic, anti-cancer, anti-aging, antibacterial, free radical scavenging, and are beneficial to human health. Rapeseed is rich in polyphenols, which is 10-30 times that of other oilseeds. Rapeseed polyphenols can be divided into free polyphenols, soluble esterified polyphenols, glycoside polyphenols and insoluble polyphenols.
The free phenolic acids in rapeseed account for 9-16% of the total phenols, among which mustard acid accounts for 70%-85% of the total free phenolic acids. In addition, it also contains a small amount of free p-salicylic acid, vanillic acid, gentian acid, protocatechuic acid, syringic acid, p-coumaric acid, ferulic acid, caffeic acid and chlorogenic acid; Conjugated phenolic acid accounts for 80% of total phenols, among which sinapine is the main one, and its content in rapeseed is about 0.4%-1.0%.
Tocopherol is one of the most widely used natural antioxidants, which can be divided into tocopherol and tocotrienol. Rapeseed oil mainly contains α - and - tocopherol, and the content of - tocopherol is relatively high. α - tocopherol has the strongest physiological activity and is beneficial to human nutrition and health. α - tocopherol mainly plays the role of antioxidant. The tocopherol content ranges from 113 to 824 mg/kg. The total tocopherol content of rapeseed oil in the upper, middle and lower reaches of the Yangtze River is 181, 289 and 470 mg/kg respectively.