Positional distribution of fatty acids in egg yolk lipids

Numerous methods for the assessment of the positional distribution of fatty acids (FAs) in triacylglycerols (TGs) and phospholipids (PLs) have been described in the literature. Most of them employ enzymatic reactions or chiral separation by high-performance liquid chromatography. Compared with most other food lipids, egg lipid has a rather unique composition, containing high amounts of TG as well as PL organized in lipoproteins. In this study, we demonstrate that the classical approach employing pancreatic lipase and phospholipase A2 is suitable for application to egg lipids. By using this method, the total distribution of FAs among the single positions of the main lipid classes in egg lipids can be measured in a rather straightforward way. Problems regarding accuracy, especially for the determination of minor and polyunsaturated fatty acids, are discussed. The presented method gave satisfactory results even for polyunsaturates such as docosahexaenoic acid down to amounts of 1% in a specific position.