Antioxidant effects of α-, γ- and δ-tocopherels (Tocs) investigated using lard, palm or corn oil as a substrate. Conformation of effects was made by determination of the peroxide (POV) and carbonyl values (COV) of the substrate, and the amount of each Toc decomposition by the AOM test.
1) With the addition of each Toc into the oils, changes in a POV and COV values were larger the lard than in the palm or corn oil. Thus, α-Toc led to a high POV of the substrate at the stage of oxidation, but showed an apparent induction period. γ- and δ-Tocs depressed an increase in POV, but did not show a clear induction period.
2) Each Toc was rapidly consumed in the order of α, γ and δ in all substrates. When the POVs reached 100, the residual Tocs remained high in the corn oil, followed by lard and then palm oil.
3) The antioxidant effects of each Toc was found to depend on the substrate. In the lard, each Toc showed remarkable antioxidant effects in the order of δ, γ and α, α-Toc functioned as a pro-oxidant in the palm oil, but γ- and δ-Tocs as antioxidants. However, none of the Tocs showed antioxidant effects in the corn oil.
