Oxidative stability, biochemical indices and characteristics of the fatty acid composition of fish protein isolated from tuna (Thunnus albacares) canning by-product stored at -24◦C for 6 months

Tuna processing by-product is estimated at more than 100,000 metric tonnes annually in Iran, which could be a potential source of edible protein in human food. Hence, recovering proteins from tuna by-products is a big achievement in the seafood industry. In this work tuna protein isolates (TPI) were extracted from dark/ red meat using the isoelectric solubilization/ precipitation method. Oxidative stability, biochemical indices and characteristics of the fatty acid composition of TPI (pH 6.5) containing 16.2% protein, 1.2% fat and mixed with a blend of salt and sucrose – as a cryostabilizer - and stored 6 months at -24°C were studied. The levels of peroxide (PV), TBARS, FFA and total volatile basic nitrogen (TVB-N) were significantly increased in TPI without cryostabilizers during the storage time. The results revealed that 22 fatty acids were identified in the light and dark tuna meat and TPI. The fatty acid composition of light and dark muscle of tuna and TPI containing salt and sucrose was the same. However a significant change was observed only in the TPI free from cryostabilizers during frozen storage. The results confirm inhibiting of lipid oxidation due to the incorporation of salt and sucrose to TPI.