Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, Yunnan, China; Yunnan Provincial Key Laboratory of Soil Carbon Sequestration and Pollution Control, Kunming 650500, Yunnan, China.
The Obstetrical Department of the First People's Hospital of Yunnan Province (The affiliated Hospital of Kunming University of Science and Technology), Kunming 650500, China.
Sci Total Environ. 2019 Jul 1;672:16-22. doi: 10.1016/j.scitotenv.2019.03.444. Epub 2019 Mar 29.
Three unsaturated fatty acids (UFAs), namely linolenic acid, linoleic acid and oleic acid, were selected to investigate the generation of persistent free radicals during heating and reheating by stove or microwave. Stove-heating and -reheating generated significant EPR signals, and quickly dissipated during cooling. When the stove-heated samples were reheated by microwave, the EPR signals were further enhanced and lasted for over 2 h. FTIR characterization showed the breaking of CC and CO bonds and LF-NMR confirmed the increased polarity after stove heating. Microwave reheating following the stove heating generated much more small molecular chemicals according to GC-MS analysis, including some ring structures, which were not detected in stove heating or microwave heating alone. We thus proposed that these ring structures, such as benzene, were involved in the formation and stabilization of free radicals. This work highlighted that the relatively long-lasting free radicals should be carefully examined in the fried food.
三种不饱和脂肪酸（UFAs），即亚麻酸、亚油酸和油酸，被选择用来研究在通过炉灶或微波炉加热和重新加热过程中持久自由基的产生。炉灶加热和重新加热会产生显著的 EPR 信号，并在冷却过程中迅速消散。当炉灶加热的样品通过微波炉重新加热时，EPR 信号进一步增强，并持续超过 2 小时。傅里叶变换红外光谱（FTIR）特征表明 CC 和 CO 键的断裂，而低场核磁共振（LF-NMR）证实了炉灶加热后的极性增加。根据气相色谱-质谱（GC-MS）分析，微波重新加热在炉灶加热之后会产生更多的小分子化学物质，包括一些环状结构，这些结构在单独的炉灶加热或微波加热中都没有被检测到。因此，我们提出这些环状结构，如苯，参与了自由基的形成和稳定。这项工作强调，在油炸食品中应该仔细检查这些相对持久的自由基。
