Submitted to: Journal of Liquid Chromatography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/1996
Publication Date: N/A
Interpretive Summary: The amounts and types of the components of fats, called triglycerides, is important for a number of reasons. The triglyceride composition of a fat or oil determines its physical properties, such as melting point, texture, and resistance to oxidation. For edible oils, the triglyceride composition also determines the nutritional and health value. Recent advances in genetic modification techniques have allowed new strains of oilseed-bearing crops to be developed which are rich in specific triglyceride components. To characterize the triglycerides in modified soybean oil samples, a technique called high-performance liquid chromatography (HPLC) was used to separate the different triglycerides. After separation, the amounts of triglycerides were determined as they passed by a mass spectrometer, a method breaking molecules into pieces and analyzing the weights of the pieces to determine what triglycerides they came from. We use a new method of introduction, called Atmospheric Pressure Chemical Ionization, to spray the triglycerides into the mass spectrometer for detection. The combination separation technique with detection method allowed us to determine which and how much of each triglyceride was present in the genetically modified soybean oil samples. This method is an excellent tool for breeders and genetic engineers in the development of new, unique oilseed products.
Technical Abstract: Canola oil triacylglycerols from genetically modified canola lines were conclusively identified by reversed-phase HPLC coupled with atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection. Spectral identification of the triacylglycerols was based on the diacylglycerol fragments and on the protonated molecular ion [M+H]**+, except trisaturates which gave no [M+H]**+. Triacylglycerols were identified and quantitated in normal, high stearic acid and high lauric acid canola varieties. The LC/APCI-MS identification of canola oil triacylglycerols allowed their quantitation by reversed-phase HPLC coupled with a commercial flame ionization detector (FID). There was agreement between fatty acid composition obtained by LC/APCI MS and LC-FID. However, the triacylglycerol resolution obtained by LC/APCI-MS was superior to LC-FID in the qualitative identification of triacylglycerols present in amounts even below one percent. The oils of the modified canola varieties, compared to typical canola oil, contained increased content of triacylglycerols known to be more oxidatively stable like stearoyloleoyllinoleoyl, distearoyllinoleoyl, stearoyldioleoyl and distearoyloleoyl glycerols in high stearic acid canola oil and dilauroyllinoleoyl, dilauroyloleoyl and lauroyldioleoyl glycerols in high lauric acid canola oil. These oils contained fewer linolenate-containing triacylglycerols known to decrease oxidative stability.