29B-1 |
Ability of antioxidants to alter interfacial tension and lipid oxidation in bulk oil |
W. CHAIYASIT, D. J. McClements, and E. A. Decker. Dept. of Food Science, Univ. of Massachusetts, Amherst, Chenoweth Lab., Box 31410, Amherst, MA 01003-1410 Chain-breaking antioxidants differ in their effectiveness at inhibiting lipid oxidation not only because of their chemical properties, but also because of their physical location within a system. Therefore it is possible that surface active antioxidants that have affinity toward the air-oil and the water-oil interfaces are more effective in bulk oil. Our objective was to evaluate the ability of a-tocopherol, d-tocopherol, butylated hydroxytoluene (BHT), and hydroxymethyl ditertiarybutylphenol to influence the interfacial tension of a water-hexadecane interface. The ability of these compounds to scavenge free radical and their antioxidant effectiveness in bulk oil were also determined. Interfacial tension was used to gauge differences in surface activity of the antioxidants. Phenolic antioxidants were added to hexadecane prior interfacial tension measurements. Partitioning of antioxidants in water phase was determined spectrophotometrically. The free radical, 2, 2-diphenyl-1-picrylhydrazyl (DPPH·) in methanol solution was used to evaluate radical scavenging activity. Lipid hydroperoxides and headspace propanal were used to follow lipid oxidation in bulk oil.
Ability of phenolic antioxidants to decrease interfacial tension was in order of d-tocopherol>a-tocopherol»hydroxymethyl ditertiarybutylphenol>BHT. Interfacial tension decreased with increasing antioxidant concentrations (0-5.0 mmol/kg hexadecane). The partitioning of antioxidants in water phase of the hexadecane-water bilayer was in order of a-tocopherol»BHT<d-tocopherol
These results indicate that the surface activity of chain-breaking antioxidant is not the only determinant of their antioxidant effectiveness in bulk oils.
Session 29B, Food Chemistry: Lipids, antioxidants and emulsifiers
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