Thermal properties and applications of the Arrhenius equation for evaluating viscosity and oxidation rates of unrefined pollock oil

Abstract

Thermal properties of unrefined pollock oil were investigated using thermogravimetric analyzer and differential scanning calorimetry. The temperature dependency of the rate constants for lipid oxidation rates and rheological properties of unrefined pollock oil were measured and modeled using the Arrhenius equation. The enthalpy of the unrefined pollock oil was 37.7 kJ/kg. The range of melting point and specific heat capacity of unrefined pollock oil was −69.5 to 14.2 °C and 1.9–3.2 kJ/kg/°C, respectively. The flow behavior index of the oil samples ranged from 0.8 to 0.9, which indicated that the unrefined pollock oil exhibited non-Newtonian fluid behavior. The oil apparent viscosity (0.13 Pa s) at −4 °C was significantly higher ( p < 0.05) than that (0.04 Pa s) at 20 and 24 °C. The average magnitude of activation energy for viscosity of the unrefined pollock oil was 27.6 kJ/mol. The predicted apparent viscosity agreed ( R 2 = 0.99) satisfactorily with the experimental apparent viscosity. The rate of lipid oxidation for unrefined pollock oil was temperature dependent ( R 2 = 0.97). The apparent activation energy for lipid oxidation of the oil was 33.2 kJ/mol. This study demonstrated that the Arrhenius equation could be used to evaluate the lipid oxidation rate and to predict the apparent viscosity of unrefined pollock oil. The storage study showed that both temperature and time influenced lipid oxidation of unrefined pollock oil.