Relative Oxidative Stability of Diacylglycerol and Triacylglycerol Oils

To compare the oxidative stability between diacylglycerol (DAG) oil and conventional triacylglycerol (TAG) oil (that is, soybean oil), the prepared stripped diacylglycerol oil (SDO) and soybean oil (SSBO) were stored at 60 °C in the dark for 144 h. During storage peroxide values (POVs), contents of aldehydes, unsaturated fatty acids were measured to evaluate the oxidative stabilities of the 2 oils. The results showed the content of C18:2, C18:3, and total unsaturated fatty acid decreased faster in DAG oil than in soybean oil, whereas the decreased rate of C18:1 was similar in 2 oils. Also, both rate constants (K1 and K2) obtained from POV (K1) and total aldehydes (K2) indicated that DAG oil (K1 = 3.22 mmol/mol FA h−1, K2 = 0.023 h−1) was oxidized more rapidly than soybean oil (K1 = 2.56 mmol/mol FA h−1, K2 = 0.021 h−1), which was mainly due to the difference of acylglycerol composition of the 2 oils along with higher C18:3 (9.6%) in SDO than SSBO (5.7%). It is concluded that DAG was more easily oxidized than soybean oil at 60 °C in the dark for 144 h.