Prooxidative and antioxidative effects of phospholipids on milk fat

The effects of dipalmitoylphosphatidylethanolamine (DPE) and dipalmitoylphosphatidylcholine (DPC) on milk fat oxidation was examined at 50°C and 95°C under various conditions by monitoring oxygen uptake and fatty acid composition. DPE strongly inhibited milk fat oxidation both at 50°C and 95°C in the absence of water. DPC was less effective than DPE. In aqueous systems, the reverse was observed. DPE accelerated milk fat oxidation at both 50°C and 95°C. DPC accelerated the oxidation at 50°C, but inhibited it at 95°C. The free amino group in DPE may be responsible for its inhibiting effect in the dry system. The accelerating activity of DPE in the aqueous system is probably due to the formation of a more dispersed structure with better oxygen accessibility.