H NMR as a simple methodology for differentiating barn and free-range chicken eggs.

The conventional intensive system produces cheap and safe chicken eggs, but exposes the animals to stress due to overcrowding on farms. This work compared the HNMR lipidic profile of chicken eggs produced in conventional and free-range systems. Sample preparation consisted of a single-step extraction and centrifugation, and the H NMR experimental time was just 3 min per sample. Eggs from free-range chickens had higher concentrations of ω-3 and ω-6 polyunsaturated fatty acids. The ratio between the signals at δ2.85 and 4.14 from bis-allylic polyunsaturated fatty acids and glycerol moiety, respectively, was able to correctly classify 93.8 % of the samples. These results were similar to those of PLS-DA, used for comparative purposes. Therefore, the proposed method could be easily used to assist quality control and fraud prevention in the egg industry. Free-range eggs had higher concentrations of cholesterol but, as they are smaller, similar amounts to conventional ones.