The antioxidant capabilities of anthocyanin and tocol extracts from black rice bran were evaluated using
an emulsion system containing either cholesterol (1.0 mg/ml) or fish oil (10 mg/ml). The cholesterol oxidation
product, 7-ketocholesterol, increased to 180.1 lg/ml in the control emulsion after 168 h of oxidation,
while it was only 15.4 and 39.0 lg/ml in the emulsions containing 1 lg/ml of the anthocyanin and
tocol extracts, respectively; but below 1.2 lg/ml in the emulsion having 5 lg/ml of anthocyanins or
tocols. In the fish oil emulsion, over 80% of C20:5 and C22:6 were oxidised after a 48 h incubation at
37 C, while they were retained above 38% and 65% in the emulsions containing 10 lg/ml of anthocyanins
and tocols, respectively, and above 85% in the emulsion containing 20 lg/ml of anthocyanins or tocols.
Compared with the tocols extract, the capability of the anthocyanin extract was relatively greater in stabilising
cholesterol but lower in inhibiting fatty acids oxidation.
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