ANTIOXIDANT PROPERTIES OF INDIVIDUAL PHOSPHOLIPIDS IN A SALMON OIL MODEL SYSTEM

The antioxidant properties of phospholipids (PL) in a refined salmon oil model system were measured by determining changes in the 2-thiobarbituric acid number and decreases in the ratio of docosahexaenoic acid (DHA)/palmitic acid (22:6/16:0) of a fish oil system incubated at 180-degrees-C for up to 3 h. The more phosphatidylcholine (PC) added to the oil system, the higher the oxidative stability obtained. The order of effectiveness of commercial phospholipids in inhibiting oxidation and the loss of polyunsaturated fatty acids was as follows: sphingomyelin (SPH) = lysophosphatidylcholine (LPC) = phosphatidylcholine (PC) = phosphatidylethanolamine (PE) > phosphatidylserine (PS) > phosphatidylinositol (PI) > phosphatidylglycerol (PG) > control salmon oil. Nitrogen containing PL, including PE, PC, LPC and SPH, were equally effective in exerting greater antioxidant properties than PS, PG and Pl. The inverse relationship observed between the oxidation index (C22:6/C16:0) and color intensity for treatments following 2 h of heating suggests that Maillard-type reaction products may have contributed to the oxidative stability of PL-supplemented fish oils.