Main causes in 3-MCPD and GE formation
The term 3-MCPD and GE as contaminants are still uncommon by some people. After knowing the health impact caused by these contaminants, it is also essential to understand more about factors that influence the formation of 3-MCPD and GE in refined edible oils. Compounds of 3-MCPD and GE were formed in the refining process, specifically at the deodorization step in which the crude edible oils were heated at high temperatures (≥200°C). Interestingly, while the formation of GE accelerates as the temperature goes up, the accumulation of 3-MCPD does not rise despite the temperature increases . In palm oil refining plants, crude palm oil is typically deodorized at 260°C . This high temperature undoubtedly could trigger the formation of both 3-MCPD and GE.
Two main precursors in crude edible oils that become sources for the formation of 3-MCPD are chlorine compounds and acyl glycerol, including monoacylglycerols (MAGs), diacylglycerols (DAGs), and triacylglycerols (TAGs) . Meanwhile, GE is mainly formed from MAGs and DAGs . Chlorine compounds are found in crude palm oil (CPO) in the forms of organochlorine and inorganic chlorine . Chlorine precursors are highly believed to accumulated from at least three sources: 1) the oil palm itself that naturally contains organochlorine; 2) fresh fruit bunches (FFB) of oil palm that fall on the soils (contaminated with fertilizers and pesticides); and 3) from water used to rinse the FFB and to extract the CPO [3,5]. Meanwhile, TAGs are the most dominant lipids in CPO, with a percentage range of 88-96%, while the remaining lipids in CPO are DAGs (4 -12%), MAGs, and free fatty acids (FFA) . Besides, the higher level of 3-MCPD and GE contents are highly related to the content of FFA. Šmidrkal et al.  reported that high contents of FFA in the CPO resulted in higher levels of 3-MCPD and GE contaminants in refined palm oil.
The consumption of refined edible oils and their derivative products in society are pretty high. Health issues caused by a high-level consumption of products that contain 3-MCPD and GE have become a concern of the European Commission. Therefore, in September 2020, the European Commission (EC) established the Commission Regulation (EU) 2020/1322, which amended the regulation (EC) No 1881/2006 regarding maximum levels of 3-MCPD, 3-MCPD fatty acid esters, and GE. In the latest regulation, the maximum levels of 3-MCPD and GE in palm oils placed on the market for the end consumer or the use of ingredients are 2.500 and 1.000 µg/kg, respectively . In addition, the maximum limits of 3-MCPD and GE contents are even smaller (750 and 500 µg/kg, respectively) that used for baby food production and processed cereal-based food for infants and young children . Consequently, Indonesia’s government and palm oil industries should ensure that palm oil products exported to mainly European countries have complied with the provisions above.
. CX/CF 18/12/9 Joint FAO/WHO Codex Alimentarius Comission (2018). Proposed draft code of practice for the reduction of 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) in refined oils and products made with refined oils, especially infant formula. Rome: Food and Agriculture Organization of the United Nations: World Health Organization. .
. Greyt, W. D. (n.d.). Deodorization. AOCS Lipid Library. https://lipidlibrary.aocs. org/edible-oil-processing/deodorization. Accessed at July 14th 2021.
. Arris, F. A., Thai, V. T. S., Manan, W. N., & Sajab, M. S. (2020). A Revisit to the Formation and Mitigation of 3-Chloropropane-1,2-Diol in Palm Oil Production. Foods, 9(12), 1769.
. Akvan, F., & Javaherdashti, R. (2016). Source detection and removal of organic chloride component in crude oil. European Corrosion Congress, EUROCORR 2016, 2, 1208 – 1216.
. Lin, S. W., Kuntom, A., Ibrahim, N. A., Ramli, M. R., Arni, R., & Razak, A. (2011). The Possible Mitigation Procedures for the Reduction of the Formation of Chloropropanol Esters and Related Compounds. Palm Oil Developments, 57, 21–27.
. Šmidrkal, J., Tesařová, M., Hrádková, I., Berčíková, M., Adamčíková, A., & Filip, V. (2016). Mechanism of formation of 3-chloropropan-1,2-diol (3-MCPD) esters under conditions of the vegetable oil refining. Food Chemistry, 211, 124–129.
. Commission regulation (EU) 2020/1322 on amending Regulation (EC) No 1881/2006 as regards maximum levels of 3‐monochloropropanediol (3-MCPD), 3-MCPD fatty acid esters and glycidyl fatty acid esters in certain foods (2020) Official Journal of the European Union, L310/4.