Stability of n-3 Fatty Acids of Fish Protein Concentrate during Drying and Storage

The susceptibility of n-3 fatty acids of fish protein concentrate to oxidation during drying and storage under different conditions was determined by gas chromatographic analyses of methylesters of fatty acids on a capillary column. Results indicate that an increase in water content of fish protein concentrate has a marked inhibitory effect on oxidative reactions. The inhibitory effect of water is most pronounced at higher water activity and the kinetics of oxidation can be represented in the initial stage by the decomposition of unsaturated fatty acids. The kinetic constants were evaluated as a function of moisture and temperature and are comparable to values reported in the literature in another oil systems. The rate of n-3 fatty acids oxidation during drying was influenced by the rate of diffusion of oxygen through the material. The use of ethoxyquin as an antioxidant prior to drying of fish protein concentrate provides a good protection against oxidation of n-3 fatty acids.