Abstract: Lipids from partially hydrogenated soybean oil and ruminant animal fat were extracted by the Folch methods, and then separated using a NH2 solid phase extraction (SPE) cartridge to obtain triglycerides and phospholipids. The analyses were carried out after using Sn-1,3-specific lipase to hydrolyze the acyl group Sn-1 and Sn-3 in triglycerides, and using phospholipase A2 to hydrolyze the acyl group at the Sn-2 position of phospholipids, which were finally converted to fatty acid methyl esters and analyzed by gas chromatography. Results showed that trans fatty acids accounted for 41.466% and 2.451%–3.179% of the total fatty acids in triglycerides from hydrogenated soybean oil and ruminant animal fat, respectively. Trans fatty acids were selectively located at the Sn-2 position of hydrogenated soybean oil triglycerides and at the Sn-1,3 position of ruminant animal fat triglycerides. For ruminant animal fat phospholipids, trans fatty acids were preferentially located at the Sn-1 position. Dietary intake of trans fatty acids from different sources and their different positional distribution preferences in triglycerides may be the cause of the fact that trans fatty acids from different sources have different impacts on human health.

Key words: trans fatty acids, triglycerides, phospholipids, positional distribution