En. Frankel et al., EVALUATION OF ANTIOXIDANT ACTIVITY OF ROSEMARY EXTRACTS, CARNOSOL ANDCARNOSIC ACID IN BULK VEGETABLE-OILS AND FISH-OIL AND THEIR EMULSIONS, Journal of the Science of Food and Agriculture, 72(2), 1996, pp. 201-208
The antioxidant effectiveness of two rosemary extracts, carnosol and c
arnosic acid, was significantly influenced by the type of system teste
d (bulk oils vs oil-in-water emulsions), by the oil substrates, the me
thods used to follow oxidation, and the concentrations of test compoun
ds. The rosemary extracts and compounds effectively inhibited conjugat
ed diene hydroperoxide formation in corn oil, soya bean oil, peanut oi
l and fish oil, when tested in bulk. Test compounds also inhibited hex
anal formation in bulk vegetable oils, and propanal and pentenal forma
tion in bulk fish oils. In contrast, these test compounds were either
inactive or promoted oxidation in the corresponding vegetable oil-in-w
ater emulsions. In fish oil emulsions, however, the rosemary compounds
inhibited the formation of conjugated diene and pentenal but not that
of propanal. Interfacial phenomena may explain why the hydrophilic ro
semary antioxidants afford more protection in the bulk oil systems by
being oriented in the air-oil interface, and less protection in the oi
l-in-water emulsion systems by partitioning into the water phase.