Thermal Oxidative Stability Analysis Of Hoki And Tuna Oils By Differential Scanning Calorimetry And Thermogravimetry

Abstract

In this study, oxidative stability of hoki and tuna oils were measured at 80°C by Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA) under an air atmosphere. The onset time for oxidation (to) of hoki oil occurred earlier in the TGA (222.50 min) compared to DSC (640.83 min) as the sample gained weight prior to decomposition. Conversely, the to of tuna oil could not be recorded since tuna oil was rapidly oxidized. The predicted shelf life of hoki oil for onset of oxygen uptake and subsequent decomposition at 4°C, by Arrhenius extrapolation of TGA and DSC under different isothermal treatments were 0.56 and 1.39 years, respectively. Temperature programmed decomposition of hoki and tuna oils by TGA occurred in three thermal stages, suggesting a progressive degradation of polyunsaturated fatty acids (PUFA), monounsaturated fatty acids (MUFA), and saturated fatty acids (SFA), followed by volatilization of polymerization and pyrolysis products.