Analysis of Oleic Acid-rich Edible Oils by Mass Spectrometry Analysis of Oleic Acid-rich Edible Oils by Mass Spectrometry

Introduction. Edible oils containing > 60 % monoenoic acids (i. e. oleic acid), in particular olive oil and Canola oil have been shown to exhibit beneficial effects on lipid metabolism in human (LDL-cholesterol blood levels, triacylglycerol blood levels) within the last few years [1]. These findings are in contrast to earlier recommandations by nutrition experts who strongly favored high-linoleic acid-containing edible oils such as sunflower oil, corn oil, soybean oil etc. Lipid diets rich in monoenoic fatty acids especially become important for patients with familial hypercholesterolaemia (FH), a genetical degeneration of the human low density lipoprotein (LDL)-receptor, in order to prevent the early development of atherosclerosis and cardiovascular deseases. Resulting effects of dietary monoenoic fatty acids on lipid blood levels are a decrease of total triacylglycerol levels, a decrease of LDL-cholesterol, and an increase of HDLcholesterol. Based on these clinical findings we became interested in the analyis of oleic acid-rich edible oils (olive oil, Canola oil, oleic acid-rich sunflower oil) with special emphasis to the characterization of oleic acid-containing triacylglycerols. Canola oil and oleic acid-rich sunflower oil are compared with other cultivars of rape and sunflower, respectively, in terms of oleic acid-distribution. The analytical protocol consiste of the determination of the triacyl-glycerol (TAG) composition as well as the elucidation of the TAG-structure of these edible oils by positive-ion electrospray ionization mass spectrometry (ESI-MS), high-energy CID/linked scanning (product ions, neutral loss) and non-aqueous reverse-phase highperformance liquid chromatography (NARP-HPLC)/atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). This analytical strategy is applied to seed oils of olive and different cultivars of rape (oleic acid-rich, erucic acid-rich) and sunflower oil (linoleic acid-rich, oleic acid-rich ones and a mixed type).