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.

Short path distillation was applied to produce edible oils low in 3‐MCPD‐FE and G‐FE, but with comparable quality to conventionally deodorized oils. By use of the Response Surface Methology the effect of different process parameters (condenser temperature (X1), evaporator temperature (X2), stirrer speed (X3) and pump frequency (X4)) on quality parameters of the oil (content of 3‐MCPD‐FE/G‐FE (minimal), acid value (minimal), content of vitamin‐E‐active compounds (sum of tocopherols and tocotrienols, maximal) and oxidation stability (maximal)) was investigated. A model was calculated for the production of refined palm oil with lowest amounts of 3‐MCPD‐FE/G‐FE and a chemical and sensory quality comparable to oil produced by standard deodorization. For the different variables of short path distillation no 3‐MCPD‐FE was detected in any of the samples, while the level for G‐FE ranged between the limit of detection and 0.7 mg/kg. A target conflict between the content of vitamin‐E‐active compounds (maximal) and acid value (minimal) was found, but in a (global) optimum of all target quality parameters (condenser temperature = 60°C, evaporator temperature = 170°C, stirrer speed = 100 rpm and pump frequency = 20 Hz) the quality of the short path distilled palm oil was comparable to conventionally refined palm oil. Slightly poorer sensory quality regarding taste and smell can be improved by a mild deodorization after short path distillation. Only the colour of the resulting oil differs from that of a conventionally refined oil, one being orange red due to the carotinoids which were not thermally decomposed. Practical Application: Mitigation of 3‐MCPD‐FE and G‐FE is a big issue in oil processing. Especially for sensible products such as baby food the content of the esters should be as low as possible without changing the quality of the edible oil. Short path distillation is known as a gentle method used for the enrichment and purification of heat‐sensitive compounds. Thus the application of short path distillation on the purification of edible oils within the refining process could be an interesting option for the production of oils low in 3‐MCPD and glycidyl esters while maintaining high oil quality. Use of Response Surface Methology short path distillation followed by mild deodorization (180°C, 120 min) has been optimized to obtain edible oils low in 3‐MCPD‐FE and G‐FE but with comparable oil quality to conventionally deodorization. Only the red colour of palm oil was not reduced by this procedure.