Oxidative stability and lipid components of eggs from flax-fed hens: Effect of dietary antioxidants and storage

January 1, 2010 Human Health and Nutrition Data 0 Comments

Oxidative stability and lipid components of eggs from flax-fed hens: Effect of dietary antioxidants and storage

Year: 2010
Authors: Hayat, Z. Cherian, G. Pasha, T.N. Khattak, F.M. Jabber, M.A.
Publication Name: Poultry Science
Publication Details: Volume 89; Pages 1285?1292.


An experiment was conducted to investigate the effect of dietary antioxidants and storage on fatty acid profile, oxidative stability, and vitamin E concentration of n-3 fatty acid-enriched eggs. Eggs (384, 48/diet) were collected from ISA Brown layers fed diets containing corn-soy (control) with 100 g/kg of flax seed and 2 types of antioxidants [α-tocopherols (α-TOC) and butylated hydroxytoluene (BHT)] at 0, 50, 100, or 150 IU or mg/kg. Eggs were stored at 4 degrees C. On day 0, 20, 40, and 60 of storage, 2 eggs were selected randomly from each replicate (totaling 12 eggs per treatment) and analyzed. Eggs from hens fed flax had increased α-linolenic (ALA,18:3n-3), eicosapentaenoic (20:5n-3), and docosahexaenoic acids (DHA, 22:6n-3) and decreased arachidonic acid (20:4n-6) and total n-6:n-3 ratio when compared with control eggs (P <0.05). The n-6:n-3 fatty acid ratio was lowest in the flax+ 50 IU of α-TOC, flax + 100 IU of α-TOC, and flax +BHT supplemented group when compared with the flax group (P < 0.05). With the exception of flax + 100 mg of BHT, addition of antioxidants led to a reduction in palmitic acid in fresh eggs (P < 0.05). During the first 20 d of storage, over a 17% reduction in total n-3 fatty acids was observed in eggs from flax + 50 mg of BHT supplemented groups (P < 0.05). Docosahexaenoic acid was the predominant long-chain n-3 fatty acid in egg and was stable during storage in the control, flax, flax + 100 IU of α-TOC, flax + 150 IU of α-TOC, and flax+ 150 mg of BHT groups. However, antioxidant supplementation had no effect on DHA upon storage in flax +50 IU of α-TOC and flax + 50 mg of BHT eggs where over 13 to 17% reduction in DHA content was observed during 20 to 60 d of storage (P < 0.05). Inclusion of α-TOC led to over 4.5- to 12-fold increases in α-TOC in eggs. Egg storage for 40 d or longer led to over 50% reduction in egg α-TOC (P < 0.05). Feeding flax seeds led to an increase in TBA reactive substances in eggs (P < 0.05). α-Tocopherol was better in preventing lipid oxidation than BHT at d 0 of storage. However, neither had a significant effect on egg TBA reactive substances upon 60 d of storage (P > 0.05). These studies demonstrate that the level and type of antioxidants and duration of egg storage significantly affected the fatty acid profile, α-TOC status, and oxidative stability of chicken eggs.(Author's abstract)
Due to limited intake of n-3 PUFA in the human diet, different strategies to produce animal food products with higher concentration of these fatty acids have been attempted in the past decade. The chicken egg has been the most reported, realistic, and successful way to incorporate n-3 fatty acids into the human diet. Incorporating different marine or vegetable oils (e.g., flax), oil seeds, or meals (plant or marine-derived) in the layer diet enhances n-3 fatty acid contents of chicken eggs.  Flax seed is the most common ingredient used for n-3 fatty acid-enriched egg production. To maintain egg quality and fatty acid stability during storage, it is essential to prevent or minimize lipid oxidation. The effect of natural versus synthetic antioxidants and their levels on fatty acid stability, α-TOC contents, and lipid oxidation products in n-3 PUFA-enriched eggs during storage is limited. In this context, the current experiment investigated the effects of dietary antioxidants (natural vs. synthetic) at 3 different levels on fatty acid profile, oxidative stability, and vitamin E concentration of n-3 fatty acid-enriched eggs throughout a 60-d refrigerated storage period. The current study demonstrated that egg yolk n-3 fatty acid and α-TOC content can be increased through diet manipulation. Consumption of 2 eggs from hens
fed the 10% flax + 150 IU of α-TOC diet could contribute to more than 500 mg of n-3 fatty acids and 11 mg of vitamin E to the human diet. Further research is needed to investigate the effect of different natural and synthetic antioxidants on fatty acid stability during storage at different time periods. (Editor's comments)

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