Contributions of different factors to ratio of 3-monochloro-1, 2-propanediol to 2-monochloro-1, 3-propanediol esters during frying simulation

Abstract

3-monochloro-1,2-propanediol (3-MCPD) and 2-monochloro-1,3-propanediol (2-MCPD) esters are internationally recognized as harmful substances that coexist and transform into each other. In this study, the clear effects (p < 0.05) of Fe3+, chloride compounds (NaCl, KCl, MgCl2, FeCl2, FeCl3), NaCl, and water on the formation of MCPD esters and the concentration ratio of 3-MCPD esters (sn-3) to 2-MCPD esters (sn-2) was discussed. MgCl2 affected the formation of the two esters the most significantly, followed by FeCl2, NaCl, KCl, and FeCl3. The 3-MCPD and 2-MCPD ester concentrations in the frying oil were proportional to the content of Fe3+, and the ratio fluctuated with an increasing Fe3+ content, suggesting that Fe3+ plays multiple roles in the formation of 2-MCPD and 3-MCPD esters. The concentration ratio of the sn-3 isomer to the sn-2 isomer was strongly dependent on the frying time, with the simultaneous addition of NaCl and water. The isomer ratio was higher for shorter frying times (1–2h) than for longer frying times (3–5h). These results enhance our understanding of the competitive formation of 3-MCPD and 2-MCPD esters during frying and allow frying food manufacturers to control the generation of these contaminants in consumer products.