Ahn, Jan 2010 – Effect of Processing, Storage and Cooking on Omega-3 Fatty Acids, Lutein and Choline in Egg Products

The objectives of this work were 1) to determine the effect of various processing (e.g., pasteurization, ultrapasteurization, spray drying and freezing) and storage of egg products (e. g., liquid egg yolk, liquid whole egg, frozen 10% salted yolk, frozen 10% sugar yolk, spray dried yolk, and spray dried whole egg) on omega-3 fatty acids, lutein and choline added during processing, and 2) to determine the effect of processing processes and storage of processed egg products on omega-3 fatty acids, lutein and choline modified through the feed. Liquid whole egg and liquid egg yolk samples were prepared and processed using pasteurization, ultrapasteurization, spray drying, or freezing, and stored. The storage time for egg samples varied depending upon processing methods used. Both raw and cooked samples were prepared and analyzed for fat content and fatty acid composition, and changes in volatiles, TBARS, lutein and choline content during processing and storage. Lutein and ω3 fatty acids could be enriched easily by adding dirtectly to the egg products before processing or through feeding diets containing them. The amounts of lutein and ω3 fatty acids enriched in egg yolk through feeding were lower than those of direct addition. However, the lutein enriched through feeding showed stronger antioxidant effect and was more stable to various processing, cooking and storage than that added directly before processing probably because the lutein enriched through feeding was distributed better than direct incorporation. Among the three functional components (lutein, ω3 fatty acids, and choline), only lutein decreased significantly mainly by storage and cooking. Processing had only minor effect on the stability of lutein. Among the processing methods, ultrapasteurization was detrimental to lutein because of two heat treatments involved (pre-heating and ultrapasteurization). Storage time had very strong impact on the stability of lutein, especially with long-term storage (> 3 months for frozen and spray dried). Lutein added directly to egg products was more susceptible to processing and storage than that enriched through feeding. In spray-dried products, more than half of the lutein directly added to egg products before processing was lost during the first 3 months of storage, and lutein added to liquid whole egg was more susceptible than that added to egg yolk, especially with spray-drying process. Significant amount of lutein was also lost by cooking of the processed egg products and 20-30% of lutein was lost during cooking of egg products. Although, the amounts of ω3 fatty acids in egg products were not changed, ω3 fatty acids-enriched egg products was more susceptible to oxidative changes and produced greater amounts of lipid-oxidation dependent volatiles than control and lutein-enriched ones. Choline was very stable and was not influenced by processing, storage, and cooking.