Mass-defect filtering of isotope signatures to reveal the source of chlorinated palm oil contaminants

Abstract

This paper reports new insights at the molecular level into the route of a worldwide problem of the food industry: the occurrence of monochloro-propanediol (MCPD) esters. The application of mass defect-driven workflows is described to generate a hypothesis on the identity and occurrence of those thermally labile, chlorinated contaminant precursors that may act as chlorine donors during the formation of MCPD esters. For the first time, holistic mass-defect filtering of isotope signatures is used to pinpoint completely unknown and unexpected chlorine-containing substances naturally present in various extracts of palm fruit and partially and fully refined oils. Supervised multivariate analysis showed the effective classification of samples from various stages of industrial processing, suggesting that these steps strongly impact a complex and dynamic pool of chlorinated substances. In-vitro experiments confirmed that several of these naturally occurring chlorinated plant constituents decompose upon heat treatment, thus potentially being a source of chlorine for further reactions with palm oil lipids in a subsequent chlorination cascade. It is hypothesised that during oil refining the organochlorines naturally present in palm fruits act as a 'chlorine source' for the generation MCPD diesters. This discovery implies that industrial efforts targeting the mitigation of chlorinated substances must intervene at the earliest possible production stage or preferably even prior to oil processing. Current performance and limitations of mass-defect filtering are discussed and future developments are outlined.

Chloropropanols, Chloropropandiols and Their Esters in Food – Formation, Occurrence, Determination, Reduction of Content

“…Nagy i wsp. [55] stwierdzili, że związki chloroorganiczne występujące w palmie oleistej ulegają rozkła-dowi w procesie otrzymywania oleju palmowego z wydzieleniem HCl, co zwiększa stężenie jonów chlorkowych. W 2006 roku oznaczono znaczące zawartości 3-MCPD (> 0,02 mg/kg) w wędzonych kiełbasach, szynkach, rybach i innych wędzonkach.…”

Direct determination of fatty acid esters of 3-chloro-1, 2-propanediol in edible vegetable oils by isotope dilution - ultra high performance liquid chromatography - triple quadrupole mass spectrometry

“…3-MCPD esters can be produced during the vegetable oil refining, especially during the high-temperature deodorization [1][2][3], and it has become a new food safety issue worldwide. While the mechanisms of their formation have not been conclusively elucidated [4,5], there is evidence suggesting that 3-MCPD esters are formed from chlorion and/or natural organochlorines present in the crude oils [6] through free radical mediated mechanisms [7,8]. The researches have shown the presence of 3-MCPD esters in foods, such as refined fats and oils [22].…”

Esters of 3-monochloropropane-1,2-diol and glycidol: no formation by deep frying during large-scale production of potato crisps

“…Here, organic or inorganic chlorine-containing compounds originating from the oil fruits, e.g. palm fruits, may release the necessary chloride ions as they decompose at temperatures of 180 °C and above [6]. The released chloride may then react with triacylglycerols in two different ways: (1) by direct nucleophilic substitution concomitantly releasing fatty acids and (2) in a two-step process involving formation of an intermediate acyloxonium ion that is subsequently ring-opened by chloride [7].…”