51A-34

K. N. TOZER, Y. Yakuda, R. Moccia, and M. Marcone. Department of Food Science, University of Guelph, Guelph, ON N1G 2W1

Aquaculture is a growing industry. However there are some challenges to the storage of fresh fish products that have to be addressed. As fresh fish products age on storage shelves, off-odours and flavours arise. These changes occur, in part, from the oxidation of lipids and contribute to a decrease in product palatability. These changes will discourage consumers from repeat purchases. Thus, extending the shelf life of fish products is one of the most important aspects to the continued growth of the aquaculture industry. By studying oxidation reactions in fresh fish, it may be possible to inhibit or slow down this degradative process thereby extending the shelf life of fish products and increase the competitiveness of the industry.

The objective was to determine the extent of lipid oxidation in fresh fish fillets during storage at 4°C.

A model system was used to reduce the variations in sampling caused by the heterogeneous nature of the fillets. Fluorescence and 2-thiobarbituric acid (TBA) test were used to determine the rate of lipid oxidation in the model system.

A model system has been successfully developed to monitor lipid oxidation. The fillets were ground into a homogeneous mass and stored in plastic containers at 4°C. The results showed that by day 10 values for both fluorescence and the 2-thiobarbituric acid test had increased substantially. The study also showed that the fluorescence shift for the aqueous phase increased from 0.6 to 3. This indicates that more primary and secondary products of oxidation were interacting with amino groups. TBA-reactive substances (TBARS) reached a maximum value of 4.5 mg TBARS/kg of fish, indicating an increase in the secondary products of lipid oxidation.

This model system is a convenient and simple procedure for the analysis of fish fillets.