Effects of tocopherols, ascorbyl palmitate, and lecithin on autoxidation of fish oil
1998
Hamilton, R.J. | Kalu, C. | McNeill, G.P. | Padley, F.B. | Pierce, J.H.
The effects of α-, γ/δ, and δ-tocopherol concentrates (0.2-2.0%) alone and in combination with ascorbyl palmitate (0.1%) and lecithin (0.5%) on oxidative stability and flavor of fish oil were studied. Stability was assessed on oil stored in air at 20°C by peroxide value (PV) and off-flavor formation. Polymer content, para-anisidine value, and conjugation were used to characterize selected samples. When used alone, the protective effect of the tocopherols, as measured by PV, was δ[double greater-than sign]γ/δ[double greater-than sign]α, especially at the 2% concentration. Binary systems of ascorbyl palmitate-lecithin and lecithin-γ/δ or-δ-tocopherol were strongly synergistic in delaying peroxidation. The ternary blends provided the greatest protection against autoxidation. Refined fish oil with 2% δ-tocopherol, 0.1% ascorbyl palmitate, and 0.5% lecithin showed no significant peroxidation at 20°C over a period of 6 mon. The original antioxidant effect noted for the ternary systems in delaying peroxidation was not reflected in improved flavor stability. Off-flavors developed within 3 wk, making the oils unsuitable for use at high concentrations in ambient products that are unprotected from air.
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