Influence of Temperature on Triacylglycerol Degradation in Camellia Seed Oil during Accelerated Thermal Oxidation

Abstract

A thermal oxidation test of Camellia seed oil (CO) was carried out at 120°C and 180°C by Rancimat instrument. The effects of temperature on the stability of CO were evaluated by measuring various chemical properties as well as the composition of nonpolar and polar triglycerides. The results showed that the rate of TAG degradation from CO during the first hour at 180°C was 4.16 times higher than at 120°C, and the formation of PTAG and TPC were 18.6 times and 8.15 times higher than at 120°C, respectively. This suggests that higher reaction temperature results in higher degree of degradation. The polymerization products (TGO and TGD), oxidation products (ox-TGM) and hydrolysates (DG and FFA) from CO were 27.67%, 59.05%, 13.32%, 66.15%, 29.28% and 5.21% after 10 hours oxidation at 120°C and 180°C, respectively, indicating that the reaction process of CO at the two temperatures was very different. The polymerization reaction was dominant at 180°C, while the oxidation reaction was the dominant reaction at 120°C. The degree of hydrolysis at 120°C was higher than at 180°C. In addition, polar compounds TGO and TGD are considered biologically toxic and cytotoxic, and, as temperature increases, the nutritional and safety characteristics of CO worsen. Therefore, the cooking temperature of CO should not be too high.