Effects of cooking methods on the n-3 PUFA content of PUFA-enriched eggs

The n-3 polyunsaturated fatty acids (PUFAs) are known for their beneficial roles in human health. Recent understanding of their importance and continued consumer demands for healthier foods had led to the incorporation of n-3 PUFAs in table eggs. However, the stability of these n-3 PUFAs in eggs as a result of cooking or temperature treatments was seldom documented. The n-3 PUFAs are known for their heat lability and as much as 50% can be destroyed by temperatures beyond 100oC. This report attempted to quantify the loss of n-3 PUFAs in n-3 PUFA-enriched eggs as a result of two commonly employed Malaysian cooking methods. Three types of eggs were used, the conventional eggs (CONV) as the control, the n-3 PUFA-enriched eggs (N-3) and eggs enriched with the docosahexaenoic acid only (DHA), which is a long chain n-3 PUFA. A total of 15 eggs per egg type were used. Each of these 15 eggs were further divided into three portions of either uncooked egg (RAW), poached in boiling waterbath (POACH) or fried without oil (FRIED) to attain a core temperature of 70 C. Fatty acids were then quantitated for all eggs and their treated portions (n=135) using gas chromatography. Results showed that most of the PUFA’s in the eggs were reduced post-cooking. The n-3 PUFA’s were significantly reduced (P<0.05) in both POACH and FRIED N-3 and DHA eggs. Poaching seemed to have negligible effect on the CONV eggs but not frying. In general, the frying process is more destructive than poaching, causing a significant 14 – 23 % loss in the n-3 PUFAs of the eggs.

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