Sw. Huang et al., ANTIOXIDANT ACTIVITY OF CARNOSIC ACID AND METHYL CARNOSATE IN BULK OILS AND OIL-IN-WATER EMULSIONS, Journal of agricultural and food chemistry, 44(10), 1996, pp. 2951-2956
This study was aimed at evaluating the antioxidant activities of carno
sic acid and its methyl ester, methyl carnosate, in inhibiting the for
mation and decomposition of hydroperoxides in bulk and emulsified corn
oil triglycerides at 60 degrees C. In both lipid systems, methyl carn
osate was a better antioxidant than carnosic acid, and both were more
active than alpha-tocopherol. The difference in antioxidant activity b
etween methyl carnosate and carnosic acid was greater in emulsion than
in bulk systems. Carnosic acid was less stable than methyl carnosate
and alpha-tocopherol in bulk corn oil and 1% Tween 20 micelle solution
. The partitioning of carnosic acid into the water phase may explain i
ts low activity in emulsions. The measurement of antioxidant depletion
may not be a valid method to evaluate antioxidant activities because
the antioxidant activities of carnosic acid and methyl carnosate were
not related to their oxidative stability in bulk oil and Tween 20 solu
tion.