Analysis of intact triacylglycerols in cold pressed canola, flax and hemp seed oils by HPLC and ESI-MS

Cold-pressed canola, hemp and flax seed oils were separated into their respective intact triglycerides via high pressure liquid chromatography (HPLC) and their fatty acids analysed. Molecular weights of the triglycerides were determined by electrospray ionization-mass spectroscopy (ESI-MS). Seven triglycerides were collected for flax seed, and trilinolenoyl-glycerol was the most abundant at 25.9%. Seven triglycerides were separated and collected for canola seed oil with dioleoyl-linolenoyl-glycerol as the most abundant (32.5%). Eight triglycerides were separated and collected from hemp seed oil with trilinoleoyl-glycerol as the most abundant (21.9%). The fatty acid profiles of the separated triglycerides for the three oils were determined to confirm the assignments. Hempseed was found to have the highest content of palmitic acid in the triglyceride fractions collected (5.6%); flax and canola had 4.1% and 3.1% respectively. The results of fatty acid composition analysis of the cold pressed oils showed oleic acid to be the most abundant fatty acid in canola oil at 57.56 ± 0.13%. Linoleic acid was the most abundant in hemp seed oil at 55.64 ± 1.21%, and linolenic acid in flax seed oil at 58.84 ± 0.91%. Enzymatic hydrolysis using pancreatic lipase treatment was performed to analyse positional distribution of fatty acids in the oils. Thin layer chromatography (TLC) was used for separation of 2-monoglycerides and free fatty acids. For all three oils, unsaturated fatty acids marginally preferred the sn-2 position on the glycerol backbone. Flaxseed had 59.1% of linolenic acid on sn-2 position. At 58.6%, oleic acid was the most abundant fatty acid at the sn-2 position in canola oil, and for linoleic acid in hemp seed oil, 58.2%. Higher ratios of saturated fatty acids to unsaturated fatty acids were located on sn-1, 3 positions.