Stability of conjugated linoleic acid isomers in egg yolk lipids during frying

The stability of conjugated linoleic acids (CLA) was studied in egg yolk during storage and frying, using gas liquid chromatography (GLC) and silver ion high-performance liquid chromatography (Ag+–HPLC). The eggs, containing 4.0% CLA per gramme of egg yolk, were stored in a refrigerator at 0–4 °C for 6 months, while the egg yolks were fried in a pan at 160–180 °C for 40 s. Either storage for 6 months or frying for 40 s did not significantly change the composition of CLA in egg yolk. However, the degradation of CLA was statistically significant, when the CLA mixture was fried under the same conditions at 160–180 °C for 40 s, suggesting that other components of egg yolk protected CLA from degradation. It is concluded that CLA is well preserved in egg before it is consumed.