Effect of Chemical Randomization on Positional Distribution and Stability of Omega-3 Oil Triacylglycerols

摘要

Randomization has been commonly used to modify the chemical and physical properties of natural fats and oils. In this study, seal blubber oil (SBO) and menhaden oil (MHO) were modified through chemical randomization using sodium methoxide, and the effect on positional distribution of fatty acids was investigated using gas chromatography (GC) and ~(13)C nuclear magnetic resonance (NMR) spectroscopy. The effect of randomization on the stability of the original oils and their randomized counterparts was analyzed by comparing conjugated dienes and thiobarbiturio acid reactive substances (TBARS) values after accelerated oxidation at 60 °C for 4 days. The omega-3 polyunsaturated fatty acids (PUFA) were distributed more evenly among the terminal sn-1,3 positions and the middle sn-2 position in chemically randomized oils when compared to the starting oils. The effect was more pronounced for SBO with omega-3 PUFA attached preferentially to sn-1,3 positions of triacylglycerols before randomization, and it was less pronounced for MHO, which contained omega-3 PUFA more evenly distributed before randomization. However, different levels of commonly known omega-3 fatty acids, namely, docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), eicosapentaenoic acid (EPA), and stearidonic acid (STA), were obtained in both original and randomized oils from GC and ~(13)C NMR spectroscopy. The stability of the randomized oils was also affected to different degrees, depending on the storage time.