3-Monochloropropane-1,2-diol reduced bioaccessibility of sn-2 palmitate via binding with pancreatic lipase in infant formula during gastrointestinal digestion.

Infant formula contains 3-monochloropropane-1,2-diol esters (3-MCPDE), which are formed during the deodorization step of vegetable oil refining. The European Food Safety Authority stated that 3-MCPDE can be hydrolyzed in the gastrointestinal tract to free-form 3-monochloropropane-1,2-diol (3-MCPD), which has potential toxicity and can be rapidly absorbed. Evaluating the effect of 3-MCPD on nutrition absorption is a prerequisite for establishing effective management strategies. A total of 66 crucial lipid molecules associated with 3-MCPD were identified based on debiased sparse partial correlation analysis. 3-MCPD affected triglyceride hydrolyzation and increased the concentration of undigested sn-2 palmitate (9.57 to 17.06 mg kg-1). 3-Monochloropropane-1,2-diol reduced the bioaccessibility of fatty acids, and more short- (31.42 to 58.02 mg kg-1) and medium-chain fatty acids (17.03 to 26.43 mg kg-1) remained unabsorbed. Lipidomic profiles of infant formula models spiked with different 3-MCPDE levels were investigated, and the results were consistent with the experiments with the commercial formula indicating lipid alteration was mainly affected by the digestive 3-MCPD. The formation of 3-MCPD ester-pancreatic lipase with the binding energy of -4.9 kcal mol-1 was more stable than triglyceride-pancreatic lipase (-4.0 kcal mol-1), affecting triglyceride hydrolyzation. 3-Monochloropropane-1,2-diol was bound to Glu13 and Asp331 residues of the pancreatic lipase via hydrogen bonds, which resulted in a conformational change of pancreatic lipase and spatial shielding effect. The existence of the spatial-shielding effect reduced the accessibility of pancreatic lipase and further affected triglyceride hydrolyzation. These findings indicated that 3-MCPD obstructed nutrient acquisition and laid the foundation for the subsequent nutrition enhancement design.

Solid-liquid equilibrium of free form of oil contaminants (3-MCPD and glycidol) in lipidic systems.

Esters of 3-monochloropropane-1,2-diol (3-MCPD) and glycidol are reported vegetable fats and oils contaminants formed during processing. During digestion, esterified forms are hydrolyzed making the free forms, with high toxicity to human health, possibly available in the digestive system, which could depend, among other factors, on the phase condition stablished in the gastrointestinal tract between contaminants and lipids. Therefore, this work was aimed at evaluating the solid-liquid equilibrium (SLE) of binary and pseudobinary mixtures of fatty acids (palmitic, oleic and stearic), triacylglycerols (tripalmitin, triolein and tristearin) and a partial acylglycerols, with 3-MCPD and glycidol, by differential scanning calorimetry (DSC) and thermodynamic modeling with Margules 2 and 3 suffixes, UNIFAC and ideal models. Melting properties of the contaminants were determined by DSC thermograms, with microstructure micrographs and compared to some predictive group contribution models (GC). 14 complete SLE phase diagrams could be determined. Results showed that the lipid compounds had high affinity with the free contaminants with probably the formation of liquid crystalline structures and/or solid solutions. The Margules 3 suffixes model showed the best fit with the lowest average relative deviations, no higher than 1%, although the parameters probably incorporated the non-ideality promoted by the crystalline phase behavior. The formation of mesophases and/or solid solutions with very high melting temperature probably means a difficulty of separating the contaminants from the lipid matrix in which, on the other hand, could avoid separation process or affect (probably decreasing) their absorption during digestion.

Deodorization of sunflower oil by high voltage electric field as a nonthermal method sunflower oil refining by electric field.

In this study, the high voltage electric field (HVEF) method was used for deodorization of sunflower oil to omit drawbacks of an established industrial method including long time, high energy, chemicals and water consumption, loss of bioactive compounds, and formation of some contaminants due to exposure to heat. Response surface methodology (RSM) was employed to find the optimal values of processing parameters. The effects of voltage (5-15 kV), clay (0-1%), electrolyte concentration (0-50 mM), the number of electrodes (1-5 pairs), and electrodes distance (1-3 cm) on the volatile compounds and tocopherols content were investigated by HS-SPME-GC/MS and HPLC, respectively. The optimal processing conditions were determined to be a voltage of 5 kV, a distance of 1 cm between the electrodes and a number of five pairs of electrodes. The amount of bleaching clay and electrolyte concentration were zero under optimal conditions. The refining process by HVEF removed 32.33% of the volatile compounds from crude sunflower oil, while the industrial refining process reduced the volatile compounds by only 17.78%. Results indicated no change was observed in the tocopherols content of refined sunflower oil by HVEF method. Based on PCA results, HVEF-treated sample not only contained the lowest concentration of volatile compounds but also was the most similar to crude sample in terms of volatile compounds composition. PRACTICAL APPLICATION: The oil refining process consists of four main stages, the last of which is deodorization. This step involves injecting steam at a temperature of about 240°C, under vacuum for about 50 min. High voltage electric field (HVEF) was able to reduce the number of volatile compounds, while no change was made in the tocopherol content of sunflower oil samples. It also does not form contaminant such as 3-monochloropropane-1,2-diol fatty acid esters and glycidyl fatty acid esters. There is no need to apply the vacuum in HVEF refining, which reduces the production cost and makes the process flow straightforward as well as rapid. This research helps to propagate green refining procedures of vegetable oils in food plants.

The occurrence of 3-monochloropropane-1,2-diol esters and glycidyl esters in vegetable oils during frying.

3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) are processed-developed contaminants presence in vegetable oils after undergo refining process under excessive heat. Refined oils are extensively used in various frying applications, nevertheless, the reservation against their quality and safety aspects are of major concern to consumers and food industry. Realizing the importance to address these issues, this article deliberates an overview of published studies on the manifestation of 3-MCPDE and GE when vegetable oils undergo for frying process. With the modest number of published frying research associated to 3-MCPDE and GE, we confined our review from the perspectives of frying conditions, product properties, antioxidants and additives, pre-frying treatments and frying oil management. Simplicity of the frying process is often denied by the complexity of reactions occurred between oil and food which led to the development of unwanted contaminants. The behavior of 3-MCPDE and GE is closely related to physico-chemical characteristics of oils during frying. As such, relationships between 3-MCPDE and/or GE with frying quality indices - i.e. acidity in term of free fatty acid or acid value); secondary oxidation in term of p-anisidine value, total polar compounds and its fractions, and refractive index - were also discussed when oils were subjected under intermittent and continuous frying conditions.

Quantification and cytotoxicity of degradation products (chloropropanols) in sucralose containing e-liquids with propylene glycol and glycerol as base.

Electronic cigarettes (e-cigarettes) have gained increasing popularity in recent years, mostly because they are supposed to be less harmful than regular cigarettes. Therefore, it is highly imperative to investigate possible noxious effects to protect the consumers. E-liquids consist of propylene glycol, glycerol, aroma compounds and sweeteners. One of these sweeteners is a chlorinated version of sucrose, namely sucralose. The aim of this work was to investigate degradation products of sucralose in the presence of propylene glycol and glycerol at different temperatures of commercially available e-cigarettes. Chemical analysis and biological tests were simultaneously performed on e-liquid aerosol condensates. The results of the chemical analysis, which was executed by employing GC-MS/GC-FID, demonstrated high amounts of various chloropropanols. The most abundant one is extremely toxic, namely 3-chloropropane-1,2-diol, which can be detected at concentrations ranging up to 10,000 mg/kg. Furthermore, a cytotoxicity investigation of the condensates was performed on HUVEC/Tert2 cells in which metabolic activity was determined by means of resazurin assay. The cellular metabolic activity significantly decreased by treatment with e-liquid aerosol condensate. Due to the results of this study, we advise against the use of sucralose as sweetener in e-liquids.

Palm oil supply chain factors impacting chlorinated precursors of 3-MCPD esters.

Chlorinated compounds such as sphingolipid-based organochlorine compounds are precursors for the formation of 3-monochlororopanediol (3-MCPD) esters in palm oil. This study evaluates the effects of several factors within the palm oil supply chain on the levels of sphingolipid-based organochlorine, which in turn may influence the formation of 3-MCPD esters during refining. These factors include application of inorganic chlorinated fertiliser in the oil palm plantation, bruising and degradation of oil palm fruits after harvest, recycling of steriliser condensate as water for dilution of crude oil during oil palm milling, water washing of palm oil and different refining conditions. It was observed that bruised and degraded oil palm fruits showed higher content of sphingolipid-based organochlorine than control. In addition, recycling steriliser condensate during milling resulted in elevated content of sphingolipid-based organochlorine in palm oil. However, the content of sphingolipid-based organochlorine compounds was reduced by neutralisation, degumming and bleaching steps during refining. Although water washing of crude palm oils (CPO) prior to refining did not reduce the content of sphingolipid-based organochlorine, it did reduce the formation of 3-MCPD esters through the removal of water-soluble chlorinated compounds. It was found that the use of inorganic chlorinated fertiliser in plantations did not increase the content of chlorinated compounds in oil palm fruits and extracted oil, and hence chlorinated fertiliser does not seem to play a role in the formation of 3-MCPD esters in palm oil. Overall, this study concluded that lack of freshness and damage to the fruits during transport to mills, combined with water and oil recycling in mills are the major contributors of chlorinated precursor for 3-MCPD esters formation in palm oil.

Occurrence of 3-monochloropropane-1,2-diol (3-MCPD) esters and glycidyl esters in infant formulas from Germany.

Fatty acid esters of 3-monochloropropane-1,2-diol (3-MCPD), 2-monochloropropanediol-1,3-diol (2-MCPD), and glycidol are heat-induced processing contaminants formed during the deodorisation step of edible oil refining. Because these compounds are potentially carcinogenic and/or genotoxic, their presence in refined oils and fats and foods containing these oils/fats poses possible health concerns. In particular, formula-fed infants may be exposed to these compounds due to their presence in commercial infant formulas. For this reason, in 2018, the European Union established maximum limits for glycidyl esters in oils/fats and infant formulas and recently, as of January 2021, implemented regulations for the sum of free 3-MCPD and 3-MCPD fatty acid esters as well. This work involved the analysis of 3-MCPD and glycidyl ester contents in 45 infant formula products purchased from German supermarkets in 2019. The data produced in this study showed that average contaminant concentrations across all manufacturers were exceptionally low, with 100% of the products analysed falling below the current EU regulation for glycidyl esters in powdered formulas and 96% of the products analysed meeting the recently implemented regulation for the sum of free and bound 3-MCPD. In addition, a comparison of the 2019 data set to occurrence data collected for German formulas purchased in 2015 showed that average bound 3-MCPD and glycidol concentrations have decreased (from 0.094 to 0.054 µg g-1 and from 0.010 to 0.006 µg g-1, respectively), likely indicating that additional/improved mitigation measures for reducing contaminant concentrations in infant formulas have been implemented over the 4-year period. The data collected in this occurrence study are suitable for estimating levels of exposure to these compounds for German infants.Abbreviations: 2-MCPD: 2-monochloropropane-1,3-diol; 3-MCPD: 3-monochloropropane-1,2-diol; ARA: arachidonic acid; CE: collision energy; CXP: collision cell exit potential; DHA: docosahexaenoic acid; DP: declustering potential; EP: entrance potential; EPA: eicosapentaenoic acid; EtOAc: ethyl acetate; IPA: isopropanol; LC-MS/MS: liquid chromatography-tandem mass spectrometry; MeOH: methanol; MTBE: methyl tert-butyl ether; SPE: solid-phase extraction.

A boronic acid-modified C60 derivatization reagent for the rapid detection of 3-monochloropropane-1,2-diol using matrix-assisted laser desorption/ionization-mass spectrometry.

RATIONALE: 3-Monochloropropane-1,2-diol (3-MCPD) is a well-known contaminant formed in food thermal processing, which could be found in a variety of foodstuffs. Due to its potential carcinogenicity, it was essential to quickly develop a rapid and high-throughput analytical method to monitor 3-MCPD in foodstuffs, which is described in this study. METHODS: 3-MCPD was extracted from foodstuffs and then was derivatized with a boronic acid-modified C60 (B-C60 ) through the boronic acid-diol reaction. Microwave heating was used to accelerate the derivatization reaction. Mass spectrometry (MS) analysis was conducted using matrix-assisted laser desorption/ionization-MS (MALDI-MS). The application of the method was validated using various smoked food samples. RESULTS: The chemical derivatization of 3-MCPD with B-C60 enabled the addition of a C60 -tag to 3-MCPD. High-throughput analysis of the sample within 0.5 h was realized. A good linear range from 0.02 to 1.5 µg mL-1 for 3-MCPD was obtained, with a detection limit of 0.005 µg mL-1 . The recoveries in spiked foodstuffs ranged from 85.4% to 115.1% with relative standard deviations of 2.0%-14.2%. This method was successfully applied to detect 3-MCPD in smoked foodstuffs. CONCLUSIONS: A quantitative method was developed for the detection of 3-MCPD in foodstuffs using B-C60 derivatization combined with MALDI-MS strategy. This proposed method may serve as a potential platform for the rapid and high-throughput analysis of 3-MCPD in foodstuffs for the purpose of food safety control.

Puerarin inhibited 3-chloropropane-1,2-diol fatty acid esters formation by reacting with glycidol and glycidyl esters.

The inhibitory effects of seven polyphenols on 3-chloropropane-1,2-diol fatty acid esters (3-MCPDE) formation were investigated in palm oil models. Results showed that there was not a positive significant correlation between the free-radical scavenging activities of the tested compounds and their 3-MCPDE-formation inhibitory activities; puerarin, with weak antioxidant activity, showed the highest inhibitory capacity. Moreover, puerarin reduced the content of glycidol and glycidyl esters (GEs), two key intermediates of 3-MCPDE formation in the oil models; and a puerarin-adduct was discovered in the oil fortified with glycidol or GEs, with its structure elucidated by LC-MS/MS and comparison with newly synthesized ones. Based on its chemical structure, we proposed that puerarin, at least in part, reacted with glycidol and GEs to inhibit 3-MCPDE formation. In addition, the formed compound, puerarin-7-O-propanediol was identified in the potato chips frying system, further confirming reacting with glycidol/GEs as a key mechanism of puerarin to inhibit 3-MCPDE formation.

Chloride reduction by water washing of crude palm oil to assist in 3-monochloropropane-1, 2 diol ester (3-MCPDE) mitigation.

Chloride reduction in crude palm oil (CPO) of greater than 80% was achieved with water washing conducted at 90°C. Inorganic chloride content in CPO was largely removed through washing, with no significant reduction in the organic chloride. Phosphorous content of CPO reduced by 20%, while trace elements such as calcium, magnesium and iron were also reduced in the washing operation. The 3-MCPDE formed in the refined, bleached and deodorised palm oil displayed (RBDPO) a linear relationship with the chloride level in washed CPO, which could be represented by the equation y = 0.91x, where y is 3-MCPDE and x represents the chloride in RBDPO refined from washed CPO. In plant scale trials using 5% water at 90°C, mild acidification of the wash water at 0.05% reduced chloride by average 76% in washed CPO. Utilising selected bleaching earths, controlled wash water temperature and wash water volume produced low chloride levels in RBDPO. Chloride content less than 1.4 mg kg-1 in plant RBDPO production was achieved, through physical refining of washed CPO containing less than 2 mg kg-1 chloride and would correspond to 3-MCPDE levels of 1.25 mg kg-1 in RBDPO. The 3-MCPDE reduced further to 1.1 mg kg-1 as the chloride level of washed CPO decreased below 1.8 mg kg-1. Chloride has been shown to facilitate the 3-MCPDE formation and its removal in lab scale washing study has yielded lower 3-MCPDE levels formed in RBDPO. In actual plant operations using washed CPO, 3-MCPDE levels below 1.25 mg kg-1 were achieved consistently in RBDPO.

Monitoring of heat-induced carcinogenic compounds (3-monochloropropane-1,2-diol esters and glycidyl esters) in fries.

3-Monochloropropane-1,2-diol (3-MCPD) esters and glycidyl esters (GE) are heat-induced contaminants which form during oil refining process, particularly at the high temperature deodorization stage. It is worth to investigate the content of 3-MCPD and GE in fries which also involved high temperature. The content of 3-MCPD esters and GE were monitored in fries. The factors that been chosen were temperature and duration of frying, and different concentration of salt (NaCl). The results in our study showed that the effect was in the order of concentration of sodium chloride < frying duration < frying temperature. The content of 3-MCPD esters was significantly increased whereas GE was significantly decreased, when prolong the frying duration. A high temperature results in a high 3-MCPD ester level but a low GE level in fries. The present of salt had contributed significant influence to the generation of 3-MCPD. The soaking of potato chips in salt showed no significant effect on the level of GE during the frying. The oil oxidation tests showed that all the fries were below the safety limit. Hence, the frying cycle, temperature and the added salt to carbohydrate-based food during frying should be monitored.

Effects of deodorization temperature and time on the formation of 3-MCPD, 2-MCPD, and glycidyl esters and physicochemical changes of palm oil.

This study verified the formation profile of esters of 3-monochloropropane-1,2-diol (3-MCPDE), 2-monochloropropane-1,2-diol (2-MCPDE), and glycidol (GE), and evaluated the physicochemical changes (free-fatty acid, acylglycerols, and colour) that occurred during the deodorization of palm oil in different conditions of time (30, 60, 90, and 120 min) and temperature (210, 230, 250, and 270 °C). Levels of 3-MCPD and 2-MCPD esters ranged from 1.91 to 2.70 mg/kg and 0.68 to 1.44 mg/kg, respectively, and were formed at the mildest tested condition (210 °C, 30 min). No correlation was observed between these contaminants and physicochemical changes. GE levels varied from 0.12 to 8.51 mg/kg and showed correlation with color and diacylglycerol content. While the temperature had little influence on the formation of esters of 3-MCPD and 2-MCPD, the content of GE considerably raised above 250 °C.

Mitigation of 3-MCPD esters and glycidyl esters during the physical refining process of palm oil by micro and macro laboratory scale refining.

The reduction of the 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) was successfully achieved by the optimization of four processing parameters: phosphoric acid dosage, degumming temperature, bleaching earth dosage, and deodorization temperature by response surface methodology without the need for additional processing steps. The optimized processing conditions were 0.31% phosphoric acid dosage, 50 °C degumming temperature, 3% bleaching earth dosage, and 240 °C deodorization temperature. The optimization resulted in more than 80% and 65% reduction of 3-MCPDE and GE levels, respectively with color and FFA contents maintained in the acceptable range specified by Palm Oil Refiners Association of Malaysia. The optimized refining condition was transferred to macro scale refining units of 1 kg and 3 kg capacities to investigate its successful application during scale-up process.

Revising degumming and bleaching processes of palm oil refining for the mitigation of 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) contents in refined palm oil.

Corresponding the high presence of 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) in refined palm oil, this paper re-evaluated degumming and bleaching processes of physical palm oil refining to reduce the amount of said contaminants. Separation-free water degumming was incorporated into the process, and this significantly (p < 0.05) reduced the esters content without compromising other oil qualities. Different types of bleaching earth (BE) were dosed at 0.5, 1.0 and 1.5% to investigate their effects on the esters formation. Results showed that different type of BE had their own optimal dosage for minimum esters formation. Surface acidity was confirmed as the key performance determinant of BE in mitigation of 3-MCPDE and GE in oil rather than the porosity profile. Specifically, BE with high acidity should be avoided, but slightly acidic BE (pH ≃ 5) was found to provide the greatest reduction of esters as compared to natural and neutral activated BE.

Optimization and validation of in-situ derivatization and headspace solid-phase microextraction for gas chromatography-mass spectrometry analysis of 3-MCPD esters, 2-MCPD esters and glycidyl esters in edible oils via central composite design.

This study aimed to develop a headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) method for the quantification of 3-monochloropropane-1,2-diol fatty acid esters (3-MCPDEs) and 2-monochloropropane-1,3-diol fatty acid esters (2-MCPDEs), and semi-quantification of glycidyl fatty acid esters (GEs) in edible oils. A central composite design was implemented to optimize the derivatization temperature and extraction time, which were 100 °C and 80 min, respectively. HS-SPME coupled with in-situ derivatization was more straightforward (three steps) and sensitive, with a limit of detection of 16% (3.9 µg/L) and 11% (5.3 µg/L) higher than that of liquid injection method, for 3-MCPD and 2-MCPD, respectively. The recoveries of 3-MCPD and 2-MCPD were in the range of 91.1% to 102.1%, with a relative standard deviation ranging from 0.08 to 9.29%. The validated methodology was successfully applied to oil samples. Further efforts will focus on shortening the extraction time, as 80 min is relatively long.

Influence of potato cultivar, frying oil and sample pre-treatments on the contamination of French fries by 3-monochloropropane-1,2-diol fatty acid esters.

This study investigated the influence of factors that could affect the levels of 3-MCPD esters in French fries, including the cultivar, the type of frying oil, and the use of pre-treatments such as blanching and application of edible coatings. Under the selected experimental conditions of frying, the cultivar Agata, which presented the highest dry matter content, showed the lowest oil uptake and 3-MCPD esters concentrations. In relation to the frying medium, the use of oils containing higher levels of 3-MCPD esters resulted in a higher contamination of French fries. Blanching treatment of potatoes before frying increased up to 33% the concentrations of 3-MCPD esters. On the other hand, the levels of the contaminants decreased by 19% with the application of a pectin solution. It could be observed that factors affecting oil uptake in French fries may also affect the contamination by 3-MCPD esters and should be considered as possible mitigation strategies to minimize human exposure to these chemical contaminants.

Effect of Anti-Clouding Agent on the Fate of 3-Monochloropropane-1,2-Diol Esters and Glycidyl Esters in Palm Olein during Repeated Frying.

Issues on 3-monochloropropane-diol-1,2-diol (MCPD) esters and glycidyl esters in refined oil have gained much attention when these heat-induced contaminants are associated with health implications. Oil that undergoes the frying process could influence the fates of 3-MCPD esters and glycidyl esters, especially with the addition of an anti-clouding agent. In this study, we investigated the effect of polyglycerol fatty acid esters (PGE) on the transients of 3-MCPD esters and glycidyl esters in palm olein (POo) during intermittent frying. Thermal resistance of POo fortified with PGE (0.1% to 0.4%) was assessed for 8 h of daily frying operations at 180 °C across five consecutive days. The addition of PGE decelerated the reduction of 3-MCPD esters and glycidyl esters with the progression of frying. The presence of these compounds coincided with the amount of oil taken up by the fried product. The inclusion of PGE in POo also induced higher augmentation of polar compound fractions, i.e., oxidised triacylglycerols (OxTAG) and polymerised triacylglycerols (PTAG), but gave comparable free fatty acid (FFA), p-anisidine value (AnV), total chloride and fatty acid composition (FAC) with control oil (POo). The results also showed that the presence of chloride in POo did not onset further formation of 3-MCPD esters and glycidyl esters throughout the frying period. As the behaviours of 3-MCPD esters and glycidyl esters were affected by PGE, only a sufficient amount should be added into POo to ensure oil clarity at a realistic period.

Removal of organochlorines from vegetable oils and its benefits in preventing formation of monochloropropanediol diesters.

This paper reports the first results on depleting certain organochlorines from vegetable oils without the use of any solvent in order to mitigate monochloropropanediol diesters (MCDPE). The concept is based on separating the organochlorines from the bulk oil by using trapping agents (e.g. monoacylglycerols) that can be easily separated from the oil. The process starts by mixing and homogenizing crude vegetable oils with the trapping agent and subsequently separating the trapping agent from the oil bulk via crystallization. The proof-of-concept of the approach is demonstrated on a spiked sunflower model system, solvent extracted crude sunflower oil, industrially produced crude soybean and corn oils. The depletion of organochlorines in the crude oils and its beneficial effect on the MCPDE content in the heat treated samples is measured by LC-MS. The depletion efficacy of the monitored organochlorines was estimated to be in the 60-95 % range. Both the melting point and polarity of the trapping agents affected the depletion efficacy of the organochlorines. Trapping agents with higher melting point and polarity, such as monostearin were more effective in comparison to high melting point but less polar agents such as palm stearin or agents rich in polar but low melting point monolinolein/monoolein. The effect of organochlorine depletion on the subsequent MPCDE levels in heat treated oil was in the range of 60-90 % reduction depending on the type of the studied oil.

Fatty Acid Esters of 3-Monochloropropanediol: A Review.

Fatty acid esters of 3-monochloropropane-1,2-diol (3-MCPD esters) are a new group of processing-induced chemical toxicants with possible nephrotoxicity and testicular toxicity. 3-MCPD esters have been detected in many food categories, including refined edible oils, bread, coffee, and infant formula. 3-MCPD esters have also been detected in human breast milk, indicating their possible absorption and distribution in human organs and tissues. 3-MCPD esters have become a food safety concern, and in 2013 the European Food Safety Authority estimated a tolerable daily value (TDI) of 2 µg/kg body weight (BW) for the amount of free 3-MCPD. This review summarizes the available information on 3-MCPD ester research, including the analytical methods, exposure biomarkers, absorption and metabolism, toxicities, formation mechanisms, and mitigation strategies as well as the occurrence of 3-MCPD esters in human foods. This review may serve as a scientific foundation for advancing our understanding of 3-MCPD esters and their food safety concerns.

Molecular Reaction Mechanism for the Formation of 3-Chloropropanediol Esters in Oils and Fats.

3-Chloro-1,2-propanediol fatty acid esters (3-MCPD esters) are a group of process-induced contaminants that form during the refining and heating of fats and oils. In this study, a combined method of simulated deodorization and computational simulation was used to explore the precursor substance and the generation path of 3-MCPD esters. From the results, 3-MCPD esters reached a content level of 2.268 mg/kg when the diacylglyceride (DAG) content was 4% and temperature was 220 °C. A good correlation was observed between DAG and 3-MCPD ester contents ( y = 0.0612 x2 - 1.6376 x + 10.558 [ R2 = 0.958]). There were three pathways for the formation of 3-MCPD esters: (A) a direct nucleophilic substitution reaction, (B) an indirect nucleophilic substitution reaction, and (C) a mechanism of an intermediate (glycidyl ester) from the calculation of Gaussian software at the B3LYP/6-31+g** level. The data showed that the ester-based direct nucleophilic substitution reaction was the most likely reaction pathway. The energy barriers for the formation of the 3-MCPD esters dipalmitin, diolein, and dilinolein were 74.261, 66.017, and 59.856 kJ/mol, respectively, indicating that the formation process of 3-MCPD esters is a high-temperature endothermic process. Therefore, by controlling the introduction of precursor (DAG) and reducing the temperature, 3-MCPD ester formation was prevented.