Changes of molecular mobility of ascorbyl palmitate and ?-tocopherol by phospholipid and their effects on antioxidant properties in bulk oil

초록

Molecular mobility of ascorbyl palmitate and alpha-tocopherol in the presence of 1,2-dioleoyl-sn-glycero-3-phos-phocholine (DOPC) were determined by NMR relaxation technique. Synergistic effects of DOPC on the anti -oxidative capacities of ascorbyl palmitate were evaluated in DPPH radical scavenging assay and bulk oil matrix. NMR relaxation technique can provide information on the mobility of protons. Molecular mobility of two protons in hydroxyl group of ascorbyl palmitate decreased by 85 and 78% in the presence of DOPC compared to those without DOPC. However, proton mobility of alpha-tocopherol increased by 41% when DOPC was present. DOPC significantly enhanced the DPPH reactivity in medium chain triacylglycerol, while this effect was not observed in alpha-tocopherol. Mixture of ascorbyl palmitate with DOPC showed synergistic antioxidant properties in corn oil at 60 degrees C. DOPC may make protons of ascorbyl palmitate in more rigid state, which can enhance hydrogen donating ability and antioxidant properties of ascorbyl palmitate in bulk oils.

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