A framework of collaborating research facilities in Germany investigates the reasons and conditions for the formation of 3-monochloro-1,2-propanediol esters (3-MCPD-E) and of glycidyl esters (GE) during edible oil refining. The aim is the derivation of technological parameters to prevent or to reduce, respectively, the formation of these contaminants during the refining process, particularly for palm oil, because the highest contents of 3-MCPD-E and related compounds were found in refined palm oils. A strong influence of the deodorization conditions was proven on the potential to form 3-MCPD-E and related compounds. Above 240°C an increased formation especially of GE was observed. Deodorization temperatures up to 240°C lead to moderate concentrations ≤5 ppm. Degumming with water, neutralization with potassium hydroxide and bleaching before deodorization is advantageous with regard to reduce the capability of vegetable oils to form the contaminants 3-MCPD and glycidyl esters.
Practical application: There is a strong demand to guarantee a stable and reliable quality of refined edible oils. The problem of 3-MCPD and glycidyl ester formation during refining has shown the sensitivity of the system to small variations in the refining conditions. In a first step it is necessary to explain the contribution of the different refining steps to the formation of contaminants.