Antioxidant synergy of alpha-tocopherol and phospholipids

The prevention of oxidation of a refined sardine oil by alpha-tocopherol at 0.04%, by several phospholipids [phosphatidylcholine (PC), phosphatidyleth anolamine (PE), and cardiolipin (CL)] at 0.5%, as well as by combinations o f a-tocopherol with each phospholipid, was investigated. The evolution of t he oxidation process during 1 mon at 40 +/- 2 degrees C was followed by a s eries of methods, measuring peroxide value (PV), diene, triene, and polyene index, and absorbance at 430 nm, while alpha-tocopherol and phospholipid c ontent were being monitoried. Among these indices, PV was found to be the m ost adequate to follow the process. PC was the most effective individual an tioxidant as shown by the PV values obtained at the end of the storage peri od, which were 54.0, 83.4, 87.9, and 97.7 meg O-2/kg for PC, CL, PE, and al pha-tocopherol, respectively. The highest synergistic effect was obtained w ith a mixture of alpha-tocopherol and PE, and the second and third best by mixtures made with PC and CL, respectively. The corresponding PV values rec orded at the end of the period were 27.0, 35.0, and 58.0 meg O-2/kg. The hi gh degree of synergy between PE and tocopherol is probably due to the occur rence of a simultaneous antioxidant mechanism involving Maillard compounds.