Background: Eggs are important foods in the daily diet of humans and have great biological activity and a high digestibility. Egg yolk is a good source of biologically active substances such as fatty acids, phospholipids, sterols and tocopherols. The eggs of seven chicken genotypes were analyzed for their chemical composition, and a detailed study of the lipids in egg yolk was conducted.
Results: Energy composition of the egg yolk and egg albumen was 29.06-30.51 MJ kg-1 and 19.77-20.93 MJ kg-1 respectively. Regarding their chemical composition: water ranged from 471.7 to 515.4 g kg-1 and 878.3-885.9 g kg-1 ; fat content in dry matter ranged from 607 to 647 g kg-1 and 6.7-11.6 g kg-1 ; protein varied from 302 to 331.7 g kg-1 and 823.6-892.5 g kg-1 ; ash ranged from 33.7 to 37.7 g kg-1 and 63.8-74.0 g kg-1 ; and nitrogen-free extracts ranged from 12.7 to 36.5 g kg-1 and 35.0-96.2 g kg-1 . The sterols and phospholipids in the yolk lipids were 16-26 g kg-1 and 59-127 g kg-1 . The main fatty acids in the lipids were oleic (39.1-47.3%) and palmitic (26.0-35.5%) acids. Cholesterol in the yolk lipids ranged from 15.9 to 25.9 g kg-1 . Phosphatidylcholine (389-573 g kg-1 ), phosphatidylethanolamine (219-355 g kg-1 ) and phosphatidylinositol (112-284 g kg-1 ) were the main phospholipids. The content of saturated fatty acids in the phospholipids was significantly higher than that in triacylglycerols.
Conclusion: Small variations in the chemical composition of eggs from seven different genotypes were observed. Significant differences in the fatty acid compositions of the main classes of phospholipids and the triacylglycerol fraction were established. © 2019 Society of Chemical Industry.
Keywords: chemical composition; eggs; fatty acids; gross energy; phospholipids; sterols.
© 2019 Society of Chemical Industry.