Abstract: In this study, we extracted lipids from seven commercially available dairy products by dichloromethane-methanol method, separated triglycerides and phospholipids from the extract by solid phase extraction (SPE) on an aminopropyl-silica gel column, and hydrolyzed triglycerides by pancreatic lipase to obtain Sn-2 monoglyceride. Then, we analyzed the fatty acid content and position distribution of triglycerides and phospholipids by gas chromatography (GC), and determined the cholesterol content by liquid chromatography (LC). Furthermore, we comparatively analyzed the lipid profile characteristics of the dairy products. Results showed that family nutrition milk powder and milk powder for middle aged and elderly people were similar to each other in fatty acid composition and content. Palmitic acid was mainly combined at the Sn-1,3 position of triglyceride in 6- to 12-month-old infant formula, but mainly combined at the Sn-2 position in family nutrition milk powder and milk powder for middle aged and elderly people. Fermentation of milk led to an increase in the content of conjugated linoleic acid and trans fatty acids and a decrease in the content of short-chain fatty acids. Cholesterol content was positively correlated with fat content in pure milk, yogurt and cheese. The contents of polyunsaturated fatty acids and conjugated linoleic acid in goat milk were higher than those in cow milk.

Key words: dairy products, lipids, populations, processing methods, dairy sources