Chlorinated precursors of 3-monochloropropanediol esters in palm oil supply chain

3-MCPD esters are present in most fat-containing food products to exert toxicity as free 3-MCPD, a non-genotoxic carcinogen after hydrolysis in the human digestive system. 3-MCPD esters form from the reaction of lipid with chlorine sources such as organochlorine compounds found in crude palm oil (CPO) to act as chlorinated precursors. Therefore, this study evaluated organochlorine compounds in palm fruit and oil. In addition to known sphingolipid-based organochlorine compounds, this study also identified several new organochlorine compounds as wax ester-, fatty acid- and diacylglycerol-based organochlorine compounds through liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis of CPO. Organochlorine compounds were established for the first time as ubiquitous in all vegetable oils in this study. Changes of organochlorine compounds content in oil palm mesocarp from 14 to 22 weeks after pollination (WAP) also were showed for the first time in this study to support organochlorine compounds as natural chemical constituents that are produced in oil palm fruits. Sphingolipidbased organochlorine compounds showed the highest reduction (>75%) before to after deodorization of bleached palm oil with minimal distillation into palm fatty acid distillate. Besides, the highest formation of 3-MCPD esters (19.00 mg/kg) were found in fraction (F5) containing sphingolipid-based organochlorine compounds obtained from silica column chromatography of CPO. Thus, supporting sphingolipid-based organochlorine as the main chlorine source for 3-MCPD esters formation among organochlorine compounds identified in this study. Sphingolipid based-organochlorine compounds in oil palm mesocarp increase by two folds within the first 6 hours and remain unchanged between 6 to 96 ii hours after harvest reported for the first time in this study. Loose fruits of oil palm that experience more environmental degradation also showed higher content of sphingolipid-based organochlorine than fresh fruits. Subsequently, this study also showed sterilizer condensate oil and empty fruit bunch oil produced in oil palm mill have higher content sphingolipid-based organochlorine compound than CPO by about 10 and 3-folds respectively for the first time. Inclusion of sterilizer condensate dilution instead of clean water dilution showed an increment in the content of sphingolipid-based organochlorine (>70%) and formation of 3-MCPD esters (>60%) after refining of CPO. This study also pioneering evaluation of changes in sphingolipid-based organochlorine content during physical, chemical refining and water washing of CPO. Chemical refining showed about 82% reduction of sphingolipid-based organochlorine content due to neutralization while physical refining showed about 42% reduction only due to the degum-bleaching approach. Meanwhile, water washing of CPO reduced 3-MCPD ester formation by removing only the water-soluble chlorinated compounds; the insoluble organochlorine compounds were not removed. This study provides new perspectives and understanding of organochlorine compounds as a chlorinated precursor for 3-MCPD ester formation in palm oil where organochlorine compounds in oils should be considered to produce 3- MCPD ester-free oil for human consumption. A more thorough and comprehensive identification of organochlorine compounds could be developed in the future to support further research on organochlorine compounds in palm oil.

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