As both of the scavenging free radical activity and reducing
power assays are only based on an environment different from a
real lipid oxidation condition to assess the antioxidant capability of
a test sample, they are hardly associated with the potential of an
antioxidant in preventing the lipid oxidation of food or a biological
fluid emulsion. The lipid substrate and natural free radicals
involved in the oxidation were not taken into consideration in the
two assays. Although several previous studies have been conducted
to evaluate the antioxidant capability of individual natural or synthetic
antioxidants, they only focused on the effect of the antioxidants on oxidative stability
in a bulk pure oil system such aswalnut, flaxseed, or rice bran oil. In
this study, the effect of each pure antioxidant on stabilizing lipids
was evaluated by using a lipid-aqueous emulsion model which was
close to the environment of human blood emulsion. The effectiveness
of an antioxidant in the emulsion model may reflect its
capability in inhibiting adverse lipid oxidation and reducing
harmful lipid oxidation products occurring in the human body.