Volatile oxidation products formed in crude herring oil under accelerated oxidative conditions

Crude fish oil produced from herring byproducts was evaluated on its oxidative stability by a number of complementary methods. The oil was placed in a closed vessel, exposed to pure oxygen, and kept at 50 °C for up to 53 h. Six volatile compounds contributing to off-flavor in the oil were followed over time. Simultaneously, conventional oxidative chemical measurements were carried out. The results showed that, apart from 4-(Z)-heptenal, all the other components increased with time. The rate of formation of fluorescent compounds, being only time-dependent, showed to be the simplest model to describe the progress of oxidation, in opposition to the development of hexanal. Development of 1-penten-3-one correlated well with peroxide and anisidine values (r = 0.938 and r = 0.931, respectively). Correlations between the volatiles were also found. Within the applied conditions, 1-penten-3-one and 2,4-(E, E)-heptadienal could be useful as volatiles indicators for the oxidative status of the oil.