Effects of brine concentration on lipid oxidation and fatty acid profile of hot-smoked tuna (Thunnus albacares) stored at 4°C

This work evaluated the development of lipid oxidation and the changes in fatty acids in hot-smoked tuna (Thunnus albacares) as a function of brine concentration. The fish were first immersed for 30 min in a brine solution at 5, 10, or 15% sodium chloride concentration. They were then smoked at 50°C for 3 hrs followed by 1 hr at 60oC and 3 hrs at 105°C. The fish were then dried for 17 hrs, cooled and stored at 4°C. Oxidative rancidity measured by the peroxide value (PV), and thiobarbituric acid number (TBA) showed an increase with storage time. The increase was inversely proportional to the brine concentration; it was more pronounced for samples immersed in 5% brine solution whereas the lowest increase was observed for samples treated with 15% salt. Fatty acid concentration exhibited changes after smoking, and this was also a function of salt concentration. The palmitic acid and stearic acid, the two main saturated fatty acids in tuna, increased after smoking at all brine concentration, whereas the contents of oleic acid, eicosapentaenoic acid and docosahexaenoic acid decreased.