Effect of Different Chlorine Sources on the Formation of 3-Monochloro-1,2-Propanediol and 2-Monochloro-1,3-Propanediol Fatty Acid Esters during Frying

Several studies indicated that chlorine salts provoke 3-monochloro-1,2-propanediol fatty acid esters (3-MCPD-FE) and 2-monochloro-1,3- propanediol fatty acid esters (2-MCPD-FE) formation in oils during frying. The amount of MCPD strongly depends on the type and the amount of chlorine salt. Food raw materials, additives themselves may contain several chlorine compounds, providing precursors for 2- and 3-MCPD-FE formation during frying. Then, the fat uptake can cause measurable concentrations in the fried food as well. This paper aims at screening chlorine compounds occurring in food industry. Influence of sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl2), ferric chloride (FeCl3) and ammonium chloride (NH4Cl) on the formation of MCPD-FE was investigated, mimicking frying conditions (175-180 degrees C, atmospheric pressure), applying high oleic sunflower oil as frying medium. 2-MCPD-FE and 3-MCPD-FE were determined by using an indirect method based on alkaline-catalyzed transesterification and GC-MS analysis. As expected, the reference sample without using any chlorine salt resulted only slight increase in 3-MCPD-FE concentration, and no increase in 2-MCPD-FE concentration. In case of the stable salts minor formation was observed. At as high as 3 % dosage of NaCl and KCl 1.6 and 2.4 mg/kg 3-MCPD-FE generated, respectively. Adding CaCl2, NH4Cl and FeCl3 resulted in very strong MCPD-FE formation by both isomers (2- and 3-MCPD-FE) in this increasing order. 0.1 % FeCl3 generated 70 mg/kg 2-MCPD-FE and 238 mg/kg 3-MCPD-FE by the end of 8-hour heating.