Effects of endogenous lipid on the functional qualities of tuna protein during cold storage

The effects of endogenous lipid on the quality of tuna protein during storage was evaluated. Defatted tuna protein was prepared and co-stored with different contents of tuna oil or soybean oil, and the functional qualities, oxidation, protein structure and lipid oxidation were compared. During storage, a higher tuna oil content caused a greater attenuation in the functional qualities of protein, including emulsifying, foaming and water absorption abilities, and tuna oil could lead to more severe attenuation than soybean oil. Besides, the higher the oxidation degree of oil, the higher the oxidation degree and the more disordered of sarcoplasmic and myofibrillar proteins, which indicated that protein oxidation could be induced by lipid oxidation and cause greater structural damage. Finally, Pearson correlation revealed that variation in myofibrillar protein more strongly affects the functional qualities than sarcoplasmic protein. Therefore, the removal of endogenous lipid had a significant positive impact on the quality stability of protein products during storage, especially for marine protein products.