Free Radical Mediated Formation of 3-Monochloropropanediol (3-MCPD) Fatty Acid Diesters

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• 作者：Xiaowei Zhang ; Boyan Gao ; Fang Qin ; Haiming Shi ; Yuangrong Jiang ; Xuebing Xu ; Liangli (Lucy) Yu
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2013
• 出版时间：March 13, 2013
• 年：2013
• 卷：61
• 期：10
• 页码：2548-2555
• 全文大小：370K
• 年卷期：v.61,no.10(March 13, 2013)
• ISSN：1520-5118

文摘

The present study was conducted to test the hypothesis that a free radical was formed and mediated the formation of 3-monochloropropanediol (3-MCPD) fatty acid diesters, a group of food contaminants, from diacylglycerols at high temperature under a low-moisture condition for the first time. The presence of free radicals in a vegetable oil kept at 120 掳C for 20 min was demonstrated using an electron spin resonance (ESR) spectroscopy examination with 5,5-dimethylpyrroline-N-oxide (DMPO) as the spin trap agent. ESR investigation also showed an association between thermal treatment degree and the concentration of free radicals. A Fourier transform infrared spectroscopy (FT-IR) analysis of sn-1,2-stearoylglycerol (DSG) at 25 and 120 掳C suggested the possible involvement of an ester carbonyl group in forming 3-MCPD diesters. On the basis of these results, a novel free radical mediated chemical mechanism was proposed for 3-MCPD diester formation. Furthermore, a quadrupole-time of flight (Q-TOF) MS/MS investigation was performed and detected the DMPO adducts with the cyclic acyloxonium free radical (CAFR) and its product MS ions, proving the presence of CAFR. Furthermore, the free radical mechanism was validated by the formation of 3-MCPD diesters through reacting DSG with a number of organic and inorganic chlorine sources including chlorine gas at 120 and 240 掳C. The findings of this study might lead to the improvement of oil and food processing conditions to reduce the level of 3-MCPD diesters in foods and enhance food safety.

Keywords:

3-MCPD diester; formation mechanism; ESR; Q-TOF MS/MS; FT-IR