Formation of 3-MCPD Fatty Acid Esters from Monostearoyl Glycerol and the Thermal Stability of 3-MCPD Monoesters

Formation of 3-monochloropropanediol (3-MCPD) esters from monostearoyl glycerol (MSG) was investigated under high temperature and low moisture conditions. Different organic and inorganic chlorides, including lindane, KCl, CaCl 2 , NaCl, MgCl 2 , AlCl 3 , CuCl 2 , MnCl 2 , SnCl 2 , ZnCl 2 , and FeCl 3 , were evaluated for their potential to react with MSG to form 3-MCPD and glycidyl esters at 120 and 240 °C using a UPLC-Q-TOF MS analysis. The results indicated that different chlorine compounds differed in their capacity to react with MSG and formed different products including 3-MCPD mono- and diesters, distearoylglycerol, and glycidyl esters. According to electron spin resonance (ESR) and Fourier transform infrared (FT-IR) spectroscopies, free radical mediated formation mechanisms involving either five-membered or six-membered cyclic acyloxonium free radicals (CAFR) from monoacylglycerol (MAG) were proposed. Tandem quadrupole-time-of-flight (Q-TOF) MS and MS/MS analyses confirmed the free radical mechanisms. In addition, the results from the present study showed that 3-MCPD monoester could be degraded upon thermal treatment and suggested a possible catalytic role of Fe 3+ under the experimental conditions.