The effect of lipoxygenase(LOX) on th oxidation and co-oxidation of lipid fraction was studied in the model system of rainbow trout. For the reaction in model system 1 g of lipid fraction and 50mL of enzyme extract(LOX, 140 unit in 50mL phosphate
buffer
solution at pH 7.4), which were obtained from rainbow trout, were homoginized in the presence of Tween 20 and kept at 23℃for 3 days. The activity of LOX was decreased to 43% of its initial level during the reaction the model system. The initial
compositionof rainbow trout lipid was showed to be consisted of trigliceride(TG ; 82%) and free fatty acid(FFA : 0.1%), while this converted to 59% of TG and 20% of FFA, respectively after reaction in model system. Change of fatty acid
composition
was
also observed and the content of linoleic acid, one of the major fatty acids, was decreased to 13% from 54% in the content of total fatty acids after reaction. The carotenoids in rainbow trout were composed of 0.4% α-carotene, 1.6% β-carotene,
80%
canthaxanthin, 7% lutein and 11% zeaxanthin, thus the canthaxanithin was the major component. This canthaxanthin was the most degraded by lipoxygenase catalyzed co-oxidation during the reaction. On the other hand the tocopherol isomers found in
the
rainbow trout were α-andβ-tocopherol, and α-tocopherol had a higher degradation rate by the lipoxygenase catalyzed co-oxidation than that of β-tocopherol of model system.
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