Thermal Stability and Kinetic Study on Thermal Degradation of Vitamin D in Fortified Canola Oil.

Nowadays, fortified vegetable oils with vitamin D are widely available in different countries and are consumed daily. The reduction rate of added vitamin D in fortified canola oil during heating process, the changes in oxidative status, and the thermal kinetic degradation of vitamin D in the fortified oil were investigated. For this purpose, canola oil was fortified at two levels of vitamin D with 5.625 µg/mL (low concentration or LC) and 13.585 µg/mL (a high concentration or HC). Samples were heated isothermally at 100, 150, and 180 °C for 30 min. The vitamin D concentration was determined by the high-performance liquid chromatographic method. The retention of vitamin D in samples treated at 100 °C for 30 min showed no significant reduction. Samples treated at 150 and 180 °C depending on the initial concentration showed the retention of 67.5% to 72.97% and 33.16% to 40.35% of vitamin D , respectively. An inverse relationship was found between the increment of lipid oxidation products (peroxide and anisidine values) and the retention of vitamin D . Kinetic parameters such as rate constant, activation energy, decimal reduction time, and quotient indicator were also calculated. An Arrhenius relationship was used for the assessment of temperature dependence of vitamin D degradation. Activation energies for vitamin D in LC and HC between 100 and 180 °C were found to be 44.01 and 38.77 kJ/mol, respectively. PRACTICAL APPLICATION: The oil can be fortified with vitamin D at low cost and offers a good bioavailability. A high-temperature cooking method may not be appropriate for the fortified products containing high lipid content.