Evaluation of Oxidative Stability and Metabolite Compounds of Yellowfin Tuna (Thunnus albacares) Under Refrigerated Storage

With the increase in the market demand for yellowfin tuna, it has become increasingly important to maintain the oxidative stability and metabolic processes of the fish. The present study aimed to measure changes in oxidative stability and biological processes during 7 d of refrigerated storage. The samples were vacuum packaged and stored under refrigerated conditions (4°C) in the laboratory, and the pH, protein oxidation, and antioxidant activity were analyzed on the 1^st, 3^rd, 5^th, and 7^th days. Changes in metabolomic compounds were investigated between days 1 and 7. There was no significant change in pH on 5 days of storage (p > 0.05) but significantly increased after 7 days (p < 0.05). With respect to oxidation, as the storage time increased, the carbonyl content also increased (p < 0.05). Fresh fish showed the highest antioxidant activity, which significantly decreased on days 3 and 5 (p < 0.05). However, it increased again with the activation of antioxidant compounds after 7 days of storage. A 1D¹H nuclear magnetic resource (NMR) spectra of yellowfin tuna revealed a significant increase in various metabolic components, including bitter peptides, antioxidants, and antimicrobials. In conclusion, although yellowfin tuna freshness and protein oxidative stability decreased, several beneficial compounds increased during 7 d of refrigerated storage.