Chloride-mediated co-formation of 3-monochloropropanediol esters and glycidyl esters in both model vegetable oils and chemical model systems.

3-Monochloropropanediol esters (3-MCPDEs) and glycidyl esters (GEs) with high toxicity have drawn global concerns due to their widespread occurrence in refined oils and oil-based foods. The effect mechanisms of organic chlorine compound lindane, inorganic chlorine compounds tetra-n-butylammonium chloride (TBAC) and sodium chloride (NaCl) on the formation of 3-MCPDEs and GEs were investigated in model oils and chemical models at 240 °C. Results showed that 3-MCPDEs contents increased with the addition of lindane and TBAC, whereas, surprisingly, GEs presented the same tendency as the results of 3-MCPDEs. This suggested that although chlorine compounds were not involved in the formation reaction of GEs, they could also promote GEs formation. Chemical model experiments confirmed that the presence of chlorine compounds led to the transformation of GEs to 3-MCPDEs and conversely 3-MCPDEs could also transform to GEs. The latter transformation rate from 3-MCPDEs to GEs was higher than the former, which might account for the fact that chlorine compounds promoted GEs formation. Additionally, it was also observed that solid NaCl did not induce the increase of 3-MCPDEs and GEs levels in chemical models, suggesting that the chlorine in NaCl, different from lindane and TBAC, was not available for 3-MCPDEs formation. The present findings give novel insights into the interactions between 3-MCPDEs and GEs formation mechanisms, which offer the theoretical basis for efficient and simultaneous inhibition of 3-MCPDEs and GEs.