| Triacylglecerol (TAG) is an important kind of lipid, which is the main source of essential fatty acids (linoleic acid and linolenic acid), fat-soluble vitamins and other non-polar compounds for human. It can cause serious illness when triacylglycerols are ingested unbalancedly. Additionally, TAG is the major component of edible oil, which can be a key indicator for oil quality and authenticity. However, it is a great challenge to analysis TAGs in natural lipids due to the high complexity. We study triacylglycerols as follows:1. In this research, a rapid method for systematic analysis of triacylglycerols in human milk, infant formula and other dairy products was established by applying supercritical fluid chromatograph (SFC) coupled with quadruple time-of-flight mass spectrometry (Q-TOF-MS), combined with chemometric tools. TAGs were separated ideally within 25 min under optimized chromatographic conditions. Hundreds of triacylglycerols and diacylglycerols were identified by high resolution mass spectrometry, including several pairs of isomers. The results showed that TAG compositions became more complex over lactation period. Content of medium-chain TAGs increased significantly, and content of linoleic acid was also enhanced in mature milk. Principal component analysis (PCA) could clearly classify human milk during different lactation period from three regions, and several potential markers were found such as O-P-L. The TAG composition in infant formula was significantly different from human milk, which mostly showed in palmitic acid didn’t occupied the sn-2 position in infant formula, and this kind of TAG structure was not conducive to fat absorption for infants. Besides, there were large diferences between infant formula and trasitional milk due to higher content of medium-chain TAGs in infant formula. Therefore, it may be necessary to develop formulated products for newborn babies, different brands of infant formula can be distinguished through PCA model, indicating that the method may have great potential for identification of fake milk powder. Cow milk and goat milk have high content of short-/medium-chain saturated fatty acids, which is quite different from human milk. Compared with cow milk, goat milk contains more complicated TAG compositions and higher levels of unsaturated fatty acid, indicating that goat milk may be more suitable as infant formula base material. This analytical method is rapid and green, providing data to the systematic study of the dairy fat.2. In this study, a high-throughput method for rapidly detecting acylglycerols in various edible oils was developed by applying supercritical fluid chromatograph (SFC) coupled with quadruple time-of-flight mass spectrometry (Q-TOF-MS), combined with chemometric tools. In the instrumental optimization process, the retention mechanism of TAGs on four different columns were comprehensively evaluated, helping to underatand the separation mechanism of SFC. Some important factors were also examined including mobile phase, column temperature, back pressure and so on. The instrument conditions were as follows:Acquity UPC2 BEH 2-EP column as stationary phase; methanol/acetonitrile/acetic acid (50/50/0.1, v/v/v) and carbon dioxide as the mobile phase; column temperature:50℃; back pressure:1600 psi. Major TAGs could be separated during 15 min, including certain pairs of TAGs which remain difficulty by traditional method. SFC-MS data were subsequently analysed by principal component analysis (PCA) to make a clear classification between six different kinds of vegetable oils. Internal and external validation were processed, showing the potential of this method in differentiating the fakes quickly.3. Considering high-price of olive oil, further quantification of olive oil adulteration was studied. The linearity is good and above 0.99. Good consistencies with labeled content of olive oil in commercial blend oils demonstrated the reliability of the quantitative method.4. A rapid method was developed by using supercritical fluid chromatography combined with mass spectrometry to separate major triacylglycerols, diacylglycerols and monoacylglycerols in hydrolysis products within 8 min. This method was applied to study reaction system of specific hydrolysis of triglycerides in milk powder catalyzed by porcine pancreatic lipase in order to investigate the effects of different reaction conditions on the acyl group transfer. The results show that an increase in the amount of lipase enhances acyl group trasfer, and this kind of phenomenon is fairly obvious in a very short reaction time. Futhermore, it verified that there was high level of acyl group transfer that hydrolysates from edible oil contained 1/3-palmitic acid monoacylglycerols. Therefore, some measures should be adopted to curb acyl transfer and improve the efficiency of hydrolysis. Otherwise, the result may be inaccurate. |
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