Oxidative kinetics of salmon oil in bulk and in nanoemulsion stabilized by marine lecithin

Salmon oil (Salmo solar) rich in long-chain polyunsaturated fatty acids was submitted to various oxidative stresses (temperature, atmosphere, presence of natural antioxidant or pro-oxidant). Oxidative kinetics of oil formulations and nanoemulsions prepared by high-pressure homogenization (1700 bars) were carried out by using conjugated dienes and infrared spectroscopy measurements. Droplet size nanoemulsion and polyene index were calculated from the fatty acid composition of oils, and the lipid fraction of emulsions were followed up over a period of 40 days. The particle size of different nanoemulsions was about 160-207 nm. The oxidative stability of salmon lecithin was higher than that of other oil samples in spite of its high LC-PUFA concentration. Crude salmon oil was better protected by its natural antioxidants (tocopherols and astaxanthin). In this study, a high concentration of alpha-tocopherol (0.2%) was used for its pro-oxidant role. The addition of quercetin improves slightly the oxidative stability of oils. However, no effect of this antioxidant was observed in emulsion, due to its insolubility in water and lipid phases. (C) 2009 Elsevier Ltd. All rights reserved.