College of Food Science and Engineering, Henan University of Technology, Zhengzhou 450001, China.
College of Food Science and Quality Engineering, Nanning University, Nanning 530200, China.
Molecules. 2022 Oct 21;27(20):7135. doi: 10.3390/molecules27207135.
To investigate the changes in chemical composition of flaxseed oil during thermal-induced oxidation and the resultant effect on thermal properties, samples with different oxidation levels were obtained by being heated at 180 °C for two hours and four hours. The oxidation degree was evaluated using peroxide value (PV), extinction coefficient at 232 nm and 268 nm (K232 and K268), and total polar compounds (TPC). Using chromatography, the fatty acid profile and triacylglycerol (TAG) profile were examined. Differential scanning calorimetry (DSC) was used to determine the crystallization and melting profiles. Thermal-induced oxidation of flaxseed oil led to a significant increase (p < 0.05) in PV, K232, K268, and TPC, but the relative content of linolenic acid (Ln) and LnLnLn reduced dramatically (p < 0.05). TPC derived from lipid degradation affected both crystallization and melting profiles. Statistical correlations showed that the onset temperature (Ton) of the crystallization curve was highly correlated with K232, TPC, and the relative content of LnLnLn (p < 0.05), whereas the offset temperature (Toff) of the melting curve was highly correlated with the relative content of most fatty acids (p < 0.05). This finding provides a new way of rapid evaluation of oxidation level and changes of chemical composition for flaxseed oils using DSC.
为了研究亚麻籽油在热诱导氧化过程中化学成分的变化及其对热性质的影响，将样品在 180°C 下加热两小时和四小时，以获得不同氧化水平的样品。通过过氧化物值（PV）、232nm 和 268nm 处的消光系数（K232 和 K268）以及总极性化合物（TPC）来评估氧化程度。使用色谱法检查脂肪酸分布和三酰基甘油（TAG）分布。使用差示扫描量热法（DSC）来确定结晶和熔融曲线。亚麻籽油的热诱导氧化导致 PV、K232、K268 和 TPC 显著增加（p < 0.05），但亚油酸（Ln）和 LnLnLn 的相对含量急剧下降（p < 0.05）。脂质降解产生的 TPC 同时影响结晶和熔融曲线。统计相关性表明，结晶曲线的起始温度（Ton）与 K232、TPC 和 LnLnLn 的相对含量高度相关（p < 0.05），而熔融曲线的结束温度（Toff）与大多数脂肪酸的相对含量高度相关（p < 0.05）。这一发现为使用 DSC 快速评估亚麻籽油的氧化水平和化学成分变化提供了一种新方法。
