The autoxidation of such n-3 polyunsaturated fatty acid (PUFA) ethyl esters
as ethyl eicosapentaenoate and ethyl docosahexaenoate was investigated at
various temperatures. Extensive studies of the oxidative reaction for ethyl
eicosapentaenoate were carried out at different oxygen levels. At the same
oxygen level and temperature, the autocatalytic reaction rate, by which ox
idation progressed in the first half period, was about 1.5-2.5 times larger
than the first-order reaction rate which governed the oxidation in the sec
ond half period. The reaction rate constants for ethyl eicosapentaenoate at
different oxygen levels correlated well with the Langmuir-type equation of
the oxygen concentration, in which the Langmuir parameter was independent
of temperature.