Volatile flavours in raw egg yolk of hens fed on different diets

BACKGROUND: Recent studies have suggested that the composition of lipophilic components of egg yolk is influenced by the feed. The aim of the present study was to isolate volatile flavours from egg yolk after different feeding trials using solvent extraction and thin layer high-vacuum distillation. The resulting aroma extract was analysed by various gas chromatographic techniques. Chickens were either fed with laying meal, laying meal plus cabbage and onion or laying meal plus rapeseed oil or held in free-range. RESULTS: The predominating odour impressions were described as onion-like. Comparing all analytical and sensory data of the flavour extracts, there were minimal differences among the respective samples. Free-range eggs contained fewer volatile compounds than the other samples, whereas rapeseed oil supplementation caused an enrichment of sulfur compounds. CONCLUSION: While data from gas chromatography/flame ionisation detection, gas chromatography/mass spectrometry and gas chromatography/olfactometry were less conclusive, the results from sulfur-specific analysis using gas chromatography/flame photometric detection showed a considerable effect. However, because of the low abundance of sulfur compounds in the yolk, these differences are not expected to be perceivable by the consumer. Copyright © 2011 Society of Chemical Industry