Oxidative Stability of Omega-3 Polyunsaturated Fatty Acids Enriched Eggs

Abstract

Omega-3 polyunsaturated fatty acids (n-3 PUFA) enriched eggs have a growing market share in the egg industry. This study examined the stability of n-3 PUFA enriched eggs fortified with antioxidants (vitamin E or organic Selenium [Sel-Plex] or both) following cooking and storage. The total fat content was not affected by cooking or simulated retail storage conditions, whereas, n-3 fatty acids were reduced. The content of n-3 fatty acids in boiled eggs was higher than in fried eggs. Lipid oxidation was significantly affected by the different cooking methods. Fried eggs contained higher levels of malondialdehyde (MDA, 2.02 μg/kg) and cholesterol oxidation products (COPs, 13.58 μg/g) compared to boiled (1.44 and 10.15 μg/kg) and raw eggs (0.95 and 9.03 μg/kg, respectively, for MDA and COPs). Supplementation of antioxidants reduced the formation of MDA by 40% and COPs by 12% in fried eggs. Although the content of MDA was significantly increased after 28 days of storage, COPs were not affected by storage. Our study indicated that the n-3 PUFA in enriched eggs was relatively stable during storage and home cooking in the presence of antioxidants.

Effects of storage and cooking on the antioxidant capacity of laying hen eggs

“…These changes may be responsible for the increased susceptibility of free amino acids, carotenoids, fatty acids to heat induced oxidation, which can lead to decreased antioxidant capacity. Cortinas et al (2003) and Ren et al (2013) reported that domestic cooking (frying, scrambling and boiling) significantly increased the MDA contents in eggs. Boiling and frying was not different with regard to the generation of MDA in fresh eggs.…”

“…The TBARs test was performed according to the method reported by Ren et al (2013) with minor modifications. Briefly, yolk samples (0.6 g) were homogenized with 2.5 mL of 1.15% KCl using an IKA T25 digital Ultra-Turrax homogenizer (IKA Ò Works, Wilmington, NC, USA).…”

“…Absorbance values were recorded at 532 nm using a SpectraMax M3 multi-mode microplate reader (Molecular device, Sunnyvale, CA, USA). The results were calculated using an extinction coefficient of 1.56 Â 10 5 M À1 cm À1 and expressed as mg of malondialdehyde (MDA) per kg of sample (Ren et al, 2013). A total of eight replicates were conducted per sample.…”

“…It is known that industrial processing techniques such as spray-drying can result in increased lipid oxidation and loss of antioxidant capacity in eggs (Galobart, Barroeta, Baucells, & Guardiola, 2001;Lai, Gray, Buckley, & Kelly, 1995;Morgan & Armstrong, 1992). Table eggs are usually subjected to domestic cooking methods such as frying, boiling, scrambling etc., which are also known to reduce the antioxidant properties and the content of free amino acids (Nimalaratne et al, 2011), and increase lipid oxidation of eggs, especially in n-3 PUFA enriched eggs (Cortinas, Galobart, Barroeta, Baucells, & Grashorn, 2003;Ren, Perez, Zuidhof, Renema, & Wu, 2013). Lipid oxidation occurs during storage, especially at elevated temperatures (Mohiti-Asli et al, 2008), and is more pronounced in n-3 PUFA enriched eggs, due mainly to the presence of the unsaturated bonds (Hayat, Cherian, Pasha, Khattak, & Jabbar, 2010;Ren et al, 2013).…”

“…Table eggs are usually subjected to domestic cooking methods such as frying, boiling, scrambling etc., which are also known to reduce the antioxidant properties and the content of free amino acids (Nimalaratne et al, 2011), and increase lipid oxidation of eggs, especially in n-3 PUFA enriched eggs (Cortinas, Galobart, Barroeta, Baucells, & Grashorn, 2003;Ren, Perez, Zuidhof, Renema, & Wu, 2013). Lipid oxidation occurs during storage, especially at elevated temperatures (Mohiti-Asli et al, 2008), and is more pronounced in n-3 PUFA enriched eggs, due mainly to the presence of the unsaturated bonds (Hayat, Cherian, Pasha, Khattak, & Jabbar, 2010;Ren et al, 2013). Most available data on lipid oxidation or oxidative stability are focused on dried egg products and omega-3 enriched eggs, whereas information on the antioxidant activity of table eggs during retail storage and cooking is limited.…”