For the reduction of 3-monochloro-1,2-propanediol fatty acid esters (3-MCPD esters) and related compounds in edible fats and oils three different strategies are conceivable: removal of critical reactants from the raw material, changing of the refining process or removal of formed 3-MCPD esters and related compounds from the refined product. This paper discusses these possibilities and shows that different raw materials have different capabilities to form 3-MCPD esters and related compounds, whereas palm oil, but also corn oil or coconut oil possess the highest potential for the formation. Washing of the raw material before the refining process with water or ethanol (75%) reduced the capability for the formation of 3-MCPD esters and related compounds in palm oil for about 20 and 25%, respectively. The paper shows that chloride and DAGs seem to be important precursors for the formation of 3-MCPD esters and related compounds. A hypothesis was defined that a content of 4% DAGs could be a threshold for a higher potential of the raw material for the formation of the esters. Using acid solutions (formic acid) instead of water for the generation of strip steam during deodorization resulted in a reduction of the formation of glycidyl esters for about 35%.Practical application: In a first statement the German Federal Institute for Risk Assessment (BfR) but also others recommended to search for alternative techniques for the production of edible oils to ensure lower levels of 3-MCPD esters and related compound. Changing the selection criteria for the raw material, improving the raw material before refining or removal of 3-MCPD esters and related compounds after refining have the advantage that the refining process which has been optimized over the last 100 years regarding oil quality does not need to be changed.

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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 2408C an increased formation especially of GE was observed. Deodorization temperatures up to 2408C 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.

In 2007 the oil producing industry and the downstream food processing industry were worried by the announcement that fatty acid esters of 3‐MCPD and later in 2008 that glycidyl esters have been found in different types of vegetable oils after processing. The reason for the concern was that the German Federal Institute for Risk Assessment assumed in a first statement the complete degradation of the esters to free 3‐MCPD and glycidol both classified by the International Agency for Research on Cancer (IARC) as possible and probably, respectively, carcinogenic to humans. In the meantime a lot of research has been done on these heat‐induced compounds to mitigate their formation during oil processing and today the content in vegetable oils could be remarkably lower if all approaches were implemented. This paper summarizes the different mitigation strategies and shows their effect on lowering the amount of 3‐MCPD and glycidyl esters in refined vegetable oils.

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