Phospholipids oxidation and foaming enhancement of egg albumen

Abstract

The oxidative stability of egg and soy lecithin in emulsions was evaluated with two transition metal ions, cupric and ferric ions, at two concentrations (50 and 500 μM). The effect of pH on lipid oxidation was also examined under these two concentrations for each ion. Egg lecithin (EL) had a similar peroxide value (PV) development pattern to soy lecithin (SL) when treated with cupric ion under both acidic and neutral pH. Acidic pH of 3 accelerated the oxidation of both EL and SL, especially with high concentration of copper. When treated with ferric ion, EL oxidized much faster than SL did. EL had higher values of thiobarbituric acid-reactive substances (TBARS) than SL, possibly because of its higher content of long-chain polyunsaturated fatty acids (PUFA). Acidic pH accelerated TBARS development for both EL and SL, but EL had more significantly increased values. Cupric ion was more powerful than ferric ion in catalyzing oxidation of both EL and SL under both acidic and neutral pH conditions as measured by TBARS. Linoleic acid may contribute to higher PV production. However, arachidonic acid and docosahexaenoic acid may have contributed more to TBARS production. Overall, SL showed better oxidative stability than EL under the experimental conditions. This study also suggests that using multiple methods is necessary in properly evaluating lipid oxidative stability. 1 Reprinted with permission from J. Agric. Food Chem.56 (23): 11424-11431 (2008), copyright© 2008. 2 Department of Food Science and Human Nutrition. 3 Author for correspondence.