Research On Simultaneous Determination Of Micronutrients And Functional Evaluation In Edible Vegetable Oil

Food is vital to human life, and vegetable oil provides essential energy and fatty acids for people’s activities and metabolism as an indispensable part of human diets. Also, it contains large amounts of fatty acids, and various nutritional metabolites such as vitamins, tocopherols, phytosterols, carotenoids, squalene and other nutritional elements. With the improvement of living standards, people become increasingly concerned about the nutrition of edible vegetable oils. To evaluate the nutrition and functions of vegetable oils is greatly significant to consumers and has great influence on the development of the oil industry. Therefore, in this paper, we established a method to simultaneously detect vitamins, phytosterols and carotenoids, evaluated the quality and nutrition of vegetable oils systematically based on the antioxidant capacity and bacteriostatic effect by correlation analysis. This study provides basic data for analysis of the quality and nutrition of vegetable oils. The main contents in this research are as follows:1. We established a method for simultaneous detection on vitamins, phytosterols and carotenoids with liquid chromatography tandem mass spectrometry(LC-MS/MS). Based on single factor experiments, we optimized the extraction factors of stigmasterol, β-sitosterol, squalene, α-tocopherol, γ-tocopherol, δ-tocopherol, carotenoids, lycopene, and lutein with the central composite design(CCD). The experimental results showed that the best extraction conditions were: ultrasonic temperature of 75 ℃, ultrasonic time of 40 min, and 100% ultrasonic power. Compared with classic reflux saponification method, this method has advantages of simple operations, short extraction time, and being suitable for large quantities of samples. We established a method of simultaneously detecting nine biologically active substances based on LC-MS/MS. The limit of detection(LOD) of this method is 2.1~50.0 ng/mL, the limit of quantification(LOQ) is 6.1~180.0 ng/mL, the recoveries of the sample range from 74.1% to 112.0%, and inter- and intra-day precision values(relative standard deviations) are between 2.1% and 9.7%. This method is highly sensitive and reliable and is suitable for simultaneous quantification of target compounds in vegetable oils.2. We investigated the antioxidant capacity of vegetable oils and molecular mechanism. With ABTS, FRAP and DPPH, ethanol was used to evaluate free radical scavenging ability. The results showed that vegetable oils containing high contents of biologically active substances, such as sunliower seed oil, rapeseed oil, sesame oil, have higher radical scavenging abilities than other vegetable oils. With the FRAP method, we systematically evaluated the correlation between the antioxidant capacity and nutritional contents in self-prepared camellia oil, and conducted statistic analysis by the SAS software to establish the model: Y=-2.1055-1.2742X1+0.3748X2-1.4091X3+2.4997X4-6.5845X5+20.404X6+15.521X7+30.007X8+431.74X9(R2=0.8401). In this model, X1 is stigmasterol, X2 is β-sitosterol, X3 squalene, X4 is α-tocopherol, X5 is γ-tocopherol, X6 is δ-tocopherol, X7 is lycopene, X8 is β-carotene, X9 is lutein, and Y is the result of the antioxidant capacity. The correlation coefficient R2 is 0.8401, and p is 0.0441(< 0.05), showing a significant correction. The model indicates that β-sitosterol, α-tocopherol, δ-tocopherol, γ-tocopherol, β-carotene, lutein and lycopene are the major components showing free radical scavenging ability in vegetable oils.3. We studied the antibacterial ability of 10 edible vegetable oils. In this study we take 10 edible vegetable oils as the major project, among which six are virgin edible vegetable oils, and four are commercial edible vegetable oils. We studied the antibactetial activity of Staohylococcus aureus Bacillus subtilis, Escherichia coli, Pseudomonas 3JW1 on vegetable oils. In six virgin edible vegetable oils, linseed oil and perilla oil, and sesame oil show the best inhibitory effects, and rapeseed oil shows the worst effect. Of the four commercially available edible vegetable oils, the best is corn oil, followed by olive oil. In addition, we examined the inhibitory effects of different levels of extraction phase on the antibacterial ability. The experimental results showed that the inhibition rates of four crude and least refined oils were above 50%, whereas those of primary and secondary rapeseed oils were below 20%, indicating that virgin oil is better than refined rapeseed oil in the antibacterial ability.