It is well-known that during preparation and processing of food undesired compounds can be formed in addition to desired components which improve the taste and palatability of the product. Examples of the undesired compounds include acrylamide, nitrosamines, PAH, or free 3-monochloropropane-1,2-diol (3-MCPD). Formation of such heat-induced contaminants depends on the processing conditions during the heating of the food. In most cases it is difficult to avoid the formation of such compounds without changing or impairing the quality of the product.
In December 2007 another heat-induced contaminant came into the focus of interest, which is known since the beginning of the 80th as a precursor for the formation of free 3-MCPD during the preparation of hydrolyzed plant proteins. The occurrence of these 3-MCPD fatty acid esters, or bound 3-MCPD, in different refined edible fats and oils was discussed in a scientific paper from the Czech group of Professor Velisek in 2006 and in November 2007 the Official Laboratory in Stuttgart also published some data on the occurrence of 3-MCPD esters in refined edible fats and oils.
The finding of 3-MCPD esters is important because the German Federal Institute for Risk Assessment (BfR), supported by the European Food Safety Authority (EFSA), assumes a 100% metabolism of the bound 3-MCPD to free 3-MCPD for which a tolerable daily intake (TDI) of 2 µg/kg body weight per day was defined. That means that by the consumption of refined fats and oils or foods based on refined fats and oils the TDI can be exceeded. Based on this assumption BfR recommended the research for the reasons of the formation of the esters and the search for alternative techniques regarding the processing of refined edible fats and oils with the aim to reduce the content of the esters.
Shortly after the first announcement, the refining process of fats and oils and especially the deodorization step were identified as the main reason for the formation of the 3-MCPD esters, and later it became clear that not only 3-MCPD esters are formed but also glycidyl esters can be found in the products. Free glycidol is classified as probably carcinogenic.
Considering this knowledge it seems relatively easy to solve the problem by avoiding the deodorization step. This is supported by the fact that neither 3-MCPD nor glycidyl esters can be found in virgin vegetable oils. But it has to be taken into account that the refining is essential to ensure the production of high-quality and safe fats and oils in such a large extent that is necessary for all the different needs in food production and nutrition. During the deodorization several undesired compounds such as hydrocarbons, PAH, or pesticides are removed making the oil usable for human consumption. Therefore, the solution which seems target-aimed at the first appearance is not applicable for most of the products and we have to go a longer and stony way to find a practicable solution for the problem of 3-MCPD and glycidyl esters in edible fats and oils. Moreover, the process of refining has been optimized over the last 100 years with respect to the product quality and also regarding environmental aspects. Thus, it is not so easy to change this good process. In addition, more knowledge about the different aspects of this multi-dimensional problem is necessary.
To solve the problem, four major questions need to be answered in the future:
What is the toxicological assessment of 3-MCPD and glycidyl esters?
Do we have reliable and robust methods for the determination of the esters or is more work necessary?
What is the mechanism of formation of the esters?
How is it possible to reduce the esters during processing without impairing the quality of the product?
At the moment the toxicological assessment of the esters is based on the assumption of the BfR, but it is not clear yet whether this “worst-case scenario” is true or not. With regard to a preventive consumer protection, this assumption is without an alternative. However, a verified toxicological assessment of the esters is inevitable to decide about the extent and the need of the minimizing strategies. For the assessment of the hazard resulting from the consumption of the esters it is important to have a reliable and robust method for the determination. There are several methods available, indirect methods determining the sum of the esters by measuring free 3-MCPD, and direct methods measuring individual esters without destroying them – but which is the best? Is there a “best method,” or does the choice depend on the question to be answered? For appropriate strategies to minimize 3-MCPD and related compounds it is necessary to know what happens during the formation. What are the precursors and which conditions are required? The aim of all the attempts to generate more knowledge about 3-MCPD and glycidyl esters has to be the development of strategies to minimize their formation. The balancing act is to find a solution which reduces the esters in refined edible fats and oils without impairing the product quality. This is a very ambitious aim but I think that we are on a good way.
The present volume covers all these aspects; the progress of the last years is reviewed and the still open questions are discussed. This is the first time that such a collection of different papers on this topic has been published, and the range of papers in this volume illustrates the complexity of the problem and how difficult it is to find an applicable solution.
I enjoyed the preparation of this volume and I thank all the authors for their interesting contributions and their work. I am also grateful to all the reviewers for their valuable and important help. In my opinion this volume gives an excellent overview of the current knowledge about 3-MCPD and glycidyl esters with the latest scientific results, and in addition the gaps and open questions are discussed, for example the 2-MCPD esters.
I am sure that everyone will find something of interest in this issue!