Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China.
Shenzhen Key Laboratory of Marine Microbiome Engineering, Shenzhen University, Shenzhen 518060, China.
J Agric Food Chem. 2020 Dec 23;68(51):15319-15326. doi: 10.1021/acs.jafc.0c05515. Epub 2020 Nov 1.
A kinetic model for glycidyl ester (GE) formation in both palm oil and chemical models during high-temperature heating was built to investigate the formation and degradation mechanisms of GEs in refined palm oil. The results showed that the formation and degradation of GEs followed pseudo-first-order reactions, and the rate constants of reaction kinetics followed the Arrhenius equation. The estimated activation energy of the GE degradation reaction (12.87 kJ/mol) was significantly lower than that of the GE formation reaction (34.58 kJ/mol), suggesting that GE degradation occurred more readily than formation. The Fourier transform infrared (FTIR) band intensities of epoxy and ester carboxyl groups decreased over heating time, while no band assigned to the cyclic acyloxonium group was found. Furthermore, no 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-cyclic acyloxonium radical adduct was detected by quadrupole time-of-flight mass spectrometry (Q-TOF-MS). The above findings indicated that GEs were decomposed, fatty acid was also liberated, and GE degradation did not involve a cyclic acyloxonium intermediate. GEs were primarily decomposed into monoacylglycerol via ring-opening reaction during heating followed by fatty acid and glycerol via hydrolysis reaction.
建立了一个动力学模型，用于研究高温加热过程中棕榈油和化学模型中缩水甘油酯（GE）的形成，以研究精炼棕榈油中 GE 的形成和降解机制。结果表明，GE 的形成和降解遵循准一级反应，反应动力学的速率常数遵循阿仑尼乌斯方程。估计的 GE 降解反应的活化能（12.87 kJ/mol）明显低于 GE 形成反应的活化能（34.58 kJ/mol），表明 GE 的降解比形成更容易发生。随着加热时间的延长，环氧和酯羧酸基团的傅里叶变换红外（FTIR）带强度降低，而没有发现分配给环状酰氧鎓基团的带。此外，通过四极杆飞行时间质谱（Q-TOF-MS）未检测到 5,5-二甲基-1-吡咯啉 N-氧化物（DMPO）-环状酰氧鎓自由基加合物。上述发现表明，GE 在加热过程中分解，释放出脂肪酸，并且 GE 降解不涉及环状酰氧鎓中间体。GE 主要通过开环反应分解为单酰基甘油，然后通过水解反应分解为脂肪酸和甘油。
