Fatty Acid and Antioxidant Composition of Conventional Compared to Pastured Eggs: Characterization of Conjugated Linoleic Acid and Branched Chain Fatty Acid Isomers in Eggs

Abstract

The objective of this study was to compare the antioxidant and fatty acid composition of conventionally raised commercial, free-range commercial, and pasture-raised local eggs. Egg characteristics and antioxidants were assessed, and the fatty acid composition was determined by gas chromatography-mass spectrometry. Pasture-raised egg yolk contained more retinol and significantly higher levels of carotenoids and α-tocopherol (p < 0.05) with no significant differences in total phenolic content. The percents of total ω-3 fatty acids were higher and ω-6:ω-3 fatty acid ratios were lower in pasture-raised and free-range eggs (p < 0.05). Branched chain fatty acids (BCFAs) and conjugated linoleic acid (CLA) isomers were identified in egg yolk. Pasture-raised eggs had significantly higher levels of BCFAs (p < 0.05). However, no differences in CLA isomers were detected. These results indicate that a beneficial profile of antioxidants and fatty acids is found in egg yolks from hens with pasture access.