Generation of monochloropropanediols (MCPDs) in model dough systems. 2. Unleavened doughs.

The contribution to monochloropropanediol (MCPD) levels in cooked wheat flour dough from glycero lipid precursors present in white flour and flour improver agents has been investigated. The results showed that monoacylglycerols, lysophospholipids, and phosphatidylglycerols present in white flour together with diacetyl tartaric acid esters of monoacylglycerols used in flour improvers were precursors of MCPDs. Diacyl- and triacylglycerols and phosphatidylchloline did not form measurable levels of MCPDs. Precursor compounds with -OH adjacent to phosphoryl or acyl groups on the glycerol skeleton were able to form MCPDs suggesting that the formation reaction involved a neighboring group mechanism. The relative rates and regioselectivity could be explained by differences in leaving group abilities and the steric and electronic effects of the acyl and phosphoryl groups, respectively. Kinetic data obtained from the addition of high purity reference lipids were used to quantify the potential contribution to MCPDs in wheat dough.