The antioxidant effects of a mixed tocopherols concentrate (m-Toc), L-ascorbyl stearate (AS) and lecithin (LE) on the preservation of β-carotene in fully hardened palm kernel oil were investigated by storage at 15°C and 60°C. The hardened oil containing 10% of stripped safflower oil was also used as a substrate.
1) During storage at 15°C, the acid value markedly increased and the color changed to bluish green in the fully hardened palm kernel oil samples except those to which LE had been added. Such changes were not observed during storage at 60°C. The peroxide value of each sample was zero.
2) In storage at 15°C, β-carotene in samples with no antioxidants was lost more rapidly than that in storage at 60°C.
After 60 days of storage, AS clearly inhibited the loss of β-carotene, so that it remained at about 4050% the added amount. However, m-Toc hardly showed such an effect, with hardly any change occurring in its amount, as was also noted for dibutyl hydroxytoluene (BHT). The addition of LE almost totally inhibited the loss of β-carotene.
3) In storage at 60°C, m-Toc and BHT slightly inhibited the loss of β-carotene, with loss being only slight for the former but considerable for the latter. LE showed a clear effect on the loss of β-carotene, and its addition along with m-Toc was the most effective. However, AS had no effect and was rapidly lost.
