Comparison of oxidative stability of diacylglycerol and triacylglycerol
2001
Nakatsugawa, K. (Showa Women's Univ., Tokyo (Japan)) | Ohashi, K. | Shimada, A.
The oxidative stability of diacyiglycerol (DAG) was compared with that of triacyiglycerol (TAG) in order to understand the oxidative behavior of DAG during oxidation at ordinary temperatures and for thermal oxidation. The fatty acid composition (C sub(16:0), 5.7 ; C sub(18:0), 2.2 ; C sub(18:1), 36.2 ; C sub(18:2), 46.7 ; C sub(18:3), 8.2 ;C sub(20:1), 0.9), tocopherol content (1058 ppm), color and other properties of DAG were adjusted to almost the same levels as those of TAG. Each was aerated (40 ml/sec) at 40 deg C for 9 days under ultraviolet radiation and for 32 days without light. Potato chips fried in DAG and TAG at 130 deg C for 5 min were irradiated by ultraviolet light at 20 deg C for 60 min. DAG and TAG were heated at 18 deg C for 12 h while gently stirring. The changes in peroxide value (POV), carbonyl value (COV), acid value (AV), amount of conjugated fatty acids, viscosity and color of each oil during these oxidation processes were measured at regular intervals, while ESR measurement was adopted for the potato chips samples. It was found that the changes in the properties of DAG under the three oxidative conditions were almost the same as those of TAG, except that the induction period for DAG as determined by POV was much longer than that of TAG, and that a decrease in lightness of DAG as determined by color-difference measurement was slightly faster than that of TAG. These results suggest that difference in molecular structure between DAG and TAG would partly influence the oxidative stability during oxidation at ordinary temperatures and thermal oxidation.
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