DSC Study of Refined Bleached Shea Olein inhibited by Oleoresin and BHT

This study explores the thermal oxidation stability of refined bleached shea olein, particularly focusing on the efficacy of oleoresins derived from ginger and turmeric as natural antioxidants compared to synthetic BHT. Using Differential Scanning Calorimetry (DSC), the onset temperatures (Te) for oxidation were measured at varying heating rates (5, 10, 15, and 20 °C/min), revealing that Te increased with higher rates. The activation energy (Ea) for uninhibited shea olein was calculated at 67.28 ± 0.5 kJ/mol, while oleoresin Oleo 1 exhibited a significantly higher Ea of 105.32 kJ/mol, indicating superior thermal stability. In contrast, Oleo 2 and BHT showed lower Ea values of 62.32 kJ/mol and 95.62 kJ/mol, respectively. The study further demonstrated that at lower concentrations (100 and 200 µg/g), there were no significant differences in Te among the inhibitors; however, at 300 µg/g, Oleo 1 provided the best stability. This suggests that the thermal stability of refined bleached shea olein is influenced by the type and concentration of inhibitors used, highlighting the potential of natural antioxidants in enhancing oil stability.