Formation of Glycidyl Fatty Acid Esters Both in Real Edible Oils during Laboratory-Scale Refining and in Chemical Model during High Temperature Exposure

Variations in 3-chloropropanol esters, glycidyl esters, and lipid accompaniments during the simulated moderate decolorization process of maize germ oil

The decolorization process of maize germ oil can simultaneously reduce the contents of beneficial lipid accompaniments for enhancing human health and risk factors. Herein, the decolorization rate, oil qualities (acid and peroxide values), lipid accompaniments (tocopherols and sterols), and risk factors, such as 3-chloropropanol esters (3-MCPDEs), glycidyl esters (GEs), were used as indicators for optimizing the decolorization condition. Results showed that by under heating at 85 °C for 30 min with magnesium silicate and activated clay (1:2, w/w), the tocopherols and sterols contents were 688.07 mg/kg and 9.89 g/kg, respectively. The 3-MCPDEs and GEs contents were 1.177 and 0.090 mg/kg, respectively, which meet the standard requirements according to the EU limit regulations for 3-MCPDEs and GEs in 2021. These results could provide a theoretical basis for the corn oil refining process and technical improvement.

Selective synthesis of triacylglycerols by the ADS-17-supported Candida antarctica lipase B through esterification of oleic acid and glycerol

BACKGROUND

Immobilized enzyme possessing both high activity and good selectivity is important in practice. In this study, Candida antarctica lipase B (CALB) was immobilized onto the macroporous resin ADS-17 for triacylglycerol (TAG) synthesis through esterification of oleic acid and glycerol. The reaction conditions were optimized by single-factor study and orthogonal test, and the reusability of the immobilized CALB (CALB@ADS-17) was evaluated. In addition, the mechanism of lipase immobilization was studied and the catalytic mechanism of CALB@ADS-17 was investigated.

RESULTS

Oleic acid conversion up to 99.20% and TAG content at 91.58 wt% could be obtained under optimal conditions. In addition, the CALB@ADS-17 retained 84.28% of its initial activity after 11 cycles of reuse. The mechanism of lipase immobilization was through hydrophobic adsorption. The relationship between temperature and oleic acid conversion was lnV0 = 6.3316 - 4.3321/T, and the activation energy (Ea) was 36.02 kJ mol-1. CALB@ADS-17 did not exhibit an obvious interfacial activation phenomenon. Its kinetic behavior can be described by the Michaelis-Menten model, whose kinetic parameters of vmax, kcat, Km, Ki, and kcat/Km were 0.01265 μmol L-1 s-1, 9310.72 s-1, 0.4907 mmol L-1, 3.997 mmol L-1, and 1.90 × 104 L mmol-1 s-1, respectively.

CONCLUSION

CALB@ADS-17 showed good esterification performance and exhibited good selectivity towards TAG generation. In addition, CALB@ADS-17 exhibited good reusability in esterification reactions and has potential in practical applications. © 2025 Society of Chemical Industry.

Efficient elimination of 3-monochloropropane-1,2-diol fatty acid ester from palm oil via using activated carbon grafted with Tween80

In the current study, we attempt to remove 3-monochloropropane-1,2-diol fatty acid ester (3-MCPD ester) from palm oil with developed composite adsorbent (Tween80 modified activated carbon [AC]), and scanning electron microscopy-energy dispersive spectrometer, Fourier transform-infrared spectroscopy, X-ray diffraction, nitrogen content adsorption-desorption and thermogravimetric analysis were used to characterize the modifications. We further examined the adsorption capability of the composite adsorbent for 3-MCPD ester and found that the highest removal efficiency was 87.36% (5.3% of adsorbent dose at 104°C for 29 min). This is approximately three times higher than that of pristine AC, implying that the composite can be employed as a novel adsorbent for 3-MCPD ester reduction. Along with the adsorption mechanism of Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin models were also tested. It has been suggested that Freundlich model could best describe the adsorption process. Adsorption was found to be well-fitted by pseudo-second-order kinetics according to the kinetic study. An endothermic and spontaneous adsorption mechanism was demonstrated by the thermodynamic studies.

Health risk assessment for dietary exposure to 3-monochloropropane-1,2-diol, 2-monochloropropane-1,2-diol, and glycidol for Italian consumers

3-Monochloropropane-1,2-diol (3-MCPD), 2-monochloropropane-1,2-diol (2-MCPD) and 2,3-epoxy-1-propanol (glycidol), in their free form or esterified to fatty acids, are food contaminants formed during the refinement of oils and fats. We conducted a survey to quantify the levels of these compounds in 130 food items, in order to assess the exposure to them in food and the consequent health risk for consumers. Food samples, including infant formula, were analysed by gas-chromatography mass spectrometry with the indirect method, and we used the latest open access food consumption database for the Italian population for a probabilistic assessment of exposure. We adopted an in silico approach to fill the gap for the toxicity of 2-MCPD. The occurrence values for the three contaminants in food were in most cases lower than or comparable to those reported in previous surveys. Exposure assessment for the most exposed individuals (95thpercentiles of consumers only) of different age groups, gave values below the tolerable daily intake recommended by the European Food Safety Authority for 3-MCPD and below the simulated or predicted toxicity thresholds for 2-MCPD, indicating a negligible risk due to dietary exposure to these contaminants. For glycidol, however, estimated exposure indicated a non-negligible increase in cancer risk, and a margin of exposure <25,000 for younger population groups, indicating a potential health concern.

Changes in stability, phytonutrients, 3-chloropropanol esters and glycidyl esters of peanut oil-based diacylglycerols during heat treatment

Diacylglycerol (DAG) is generally considered one of the precursors of 3-chloropropanol esters (3-MCPDE) and glycidyl esters (GEs). This study aimed to evaluate static heating and stir-frying properties of peanut oil (PO) and PO based 58% and 82% DAG oils (PDAG-58 and PDAG-82). Observations revealed that, phytonutrient levels notably diminished during static heating, with PDAG exhibiting reduced oxidative stability, but maintaining a stability profile similar to PO over a short period. During stir-frying, 3-MCPDE content initially increased and then decreased whereas the opposite was observed for GEs. Furthermore, as temperature, and NaCl concentration increased, there was a corresponding increase in the levels of 3-MCPDE and GEs, although remained within safe limits. When used in suitable concentrations, these findings underscore the potential of DAG, as a nutritionally rich and oxidatively stable alternative to conventional cooking oils, promoting the use of DAG edible oil in heat-cooked food systems.

Exposure to Dietary Glycidyl and 3-MCPD Fatty Acid Esters and Associated Burden of Cancer in Selected Asian and European Countries: A Review and Data Synthesis

This study evaluated the health implications and oncological impact of consuming glycidyl esters (GE) and 3-monochloro-1,2-propanediol esters (3-MCPDE) in selected Asian and European populations. Data on dietary GE and 3-MCPDE were compiled from 10 studies conducted in China, Taiwan, Poland, and Spain, identified through a systematic search in PubMed and ScienceDirect databases from 2012 to 2022. Studies on food supplements and analytical methods were excluded from the analysis. Health metrics for these nations, spanning 2015 to 2019, were sourced from the Institute of Health Metrics and Evaluation, among others. A Monte Carlo Simulation was employed for data analysis. The results showed that "grains and grain products" was the most consumed food category (260.45-395.35 g/day), whereas "food for infants and children" was the least consumed (0.01-0.09 g/day). Additionally, "fats from animal or plant origin" had the highest contamination levels. While 3-MCPDE exposures remained within safe limits, median GE exposure correlated with an incidence of colon cancer ranging from 3.66 × 10-8 to 0.744%, lung cancer from 0.00256 to 0.287%, and breast cancer from 0.0262 to 2.42% within the study areas. This translated to a total cancer burden of 6.69 to 1020 Disability-Adjusted Life Years (DALYs) per 100 000 individuals. The population in China recorded the highest DALY rate (1,020), followed by Spain (30.2), Poland (19.7), and Taiwan (6.69). Projections suggest an uptick in GE-related cancer cases and associated burdens in the coming decades attributed to demographic shifts, ageing populations, and dietary changes. The study underscores the urgency of mitigating GE and 3-MCPDE food contamination, bolstering public health awareness, and establishing safety guidelines.

Multiple Mechanisms of Haematococcus pluvialis-Derived Carotenoids to Inhibit Glycidyl Ester Formation in Rice Oil and a Chemical Model at High Temperatures

The common presence of glycidyl esters (GEs) in refined vegetable oils has been a concern for food safety. The present study aimed to investigate the inhibitory effects of three carotenoids derived from Haematococcus pluvialis microalga on GE formation in both rice oil and a chemical model during heating. The addition of astaxanthin (AS), lutein (LU), and β-carotene (CA) at 0.6 mg/g in rice oil can reduce GE formation by 65.0%, 57.1%, and 57.5%, respectively, which are significantly higher than those achieved by common antioxidants such as l-ascorbyl palmitate (39.0%), α-tocopherol (18.5%), tert-butyl hydroquinone (42.7%), and quercetin (26.2%). UPLC-Q-TOF-MS/MS analysis showed that two new compounds, that is, propylene glycol monoester and diester of palmitic acid, were formed in the CA-added chemical model, which provided direct experimental evidence for the inhibition of antioxidants including AS, LU, and CA against GE formation not only by indirect antioxidative action but also by direct radical reactions to competitively prevent the formation of cyclic acyloxonium intermediates. Furthermore, it was interestingly found that only AS could react with the GEs. The adduct of AS with GEs, astaxanthin-3-O-propanetriol esters, was preliminarily identified using Q-TOF-MS/MS in the heated AS-GE model, suggesting that reacting with GEs might represent another distinct mechanism of AS to eliminate GEs.

Occurrence of 3-monochloropropane-1,2-diol and glycidyl esters in artisanal vegetable edible oils

The safety of vegetable oils has come under intense scrutiny ever since the International Agency for Research on Cancer issued an alert on the carcinogenic properties of 3-monochloropropane-1,2-diol fatty acid esters (3-MCPDE) and glycidyl esters (GE). In this study, a total of 114 samples of artisanal palm oil (PO), palm kernel oil (PKO), and coconut oil (CO) were sourced from three regions in Ghana. The concentrations of 3-MCPDE and GE were quantified using the indirect method with gas chromatography-mass spectrometry. Subsequently, the statistical distribution functions of the concentrations of the esters were fitted using the Palisade @risk software. The relationships between the esters in the oils were determined using the Pearson correlation coefficient. The results showed no correlation (p > 0.05) between the concentrations of 3-MCPDE and GE. However, 18-60 % of the sampled PO contained 3-MCPDE above the European Commission's 2.5 mg/kg limit. In comparison, 24-35 % of the PO contained GE at levels exceeding the Commission's 1 mg/kg limit. Similarly, 25-35 % of PKO samples had GE concentrations above the limit. CO was the least contaminated oil, with little or no evidence of 3-MCPE and GE formation. Though the most frequently occurring (modal) concentrations of the esters were below the limits imposed by the Commission, it is the 95th percentile level of concentrations, especially for PO, that pose a health concern. Serious education and control must be exercised over the production of PO to enhance safety at the national and international markets.

Preliminary assessments of population exposure to glycidyl esters and 3-monochloropropane-1,2-diol esters from miscellaneous oil-containing packaged foods in Taiwan

Glycidyl esters (GEs) and 3-monochloropropane-1,2-diol esters (3-MCPDEs) are carcinogenic contaminants found in refined oils. This study aimed to determine levels of GEs and 3-MCPDEs in packaged foodstuffs, and estimate daily exposure levels using food consumption data. The analysis involved Soxtec extraction and gas chromatography-mass spectrometry, and the recovery of spiked GEs and 3-MCPDEs was within the range of 80%∼110%. Results showed that GEs and 3-MCPDEs were almost ubiquitous in food products (95%), with the highest concentrations found in processed fats, followed by cookies and spreads. Food products containing palm-derived oils had significantly higher levels of contaminants (p < 0.05), with up to 58.1% of palm oil-containing foodstuffs exceeding the upper limits of either GEs or 3-MCPDEs set by the European Union. Cookies and instant noodles were identified as the main sources of exposure to GEs and 3-MCPDEs, with potential daily intake levels exceeding the tolerable daily intakes in children aged 0 ∼ 12 years.

Mitigation of 3-monochloropropane 1,2 diol ester and glycidyl ester in refined oil - A review

The 3-Monochloropropane-1, 2-diol ester (3-MCPDE) and glycidyl ester (GE) are formed at high processing temperatures with the presence of respective precursors. Both are potentially harmful to humans, causing adverse health impacts including kidney damage, reproductive problems, and increased risk of cancer. The presence of 3-MCPDE and GE in palm oil is of particular concern because of its widespread use by the food industry. There are a variety of methods for reducing 3-MCPDE and GE. For example, water washing eliminates mostly inorganic chlorides that, in turn, reduce the formation of 3-MCPDE. 3-MCPDE has also been reduced by up to 99% using combinations of methods and replacing stripping steam with alcohol-based media. Activated carbon, clay, antioxidants, potassium-based salts, and other post-refining steps have positively lowered GE, ranging from 10 to 99%. Several approaches have been successful in reducing these process contaminants without affecting other quality metrics.

Effects of deodorization on the content of polycyclic aromatic hydrocarbons (PAHs), 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) in rapeseed oil using ethanol steam distillation at low temperature

High temperature is beneficial for the removal of polycyclic aromatic hydrocarbons (PAHs) from oil via steam, but leads to an increase in the content of 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE). To inhibit the production of 3-MCPDE and GE during the removal of PAHs, rapeseed oil was deodorized using ethanol steam at low-temperature (140-220 °C) (L-ESD) and the content changes were studied for PAHs, 3-MCPDE and GE, and compared with conventional high-temperature water steam deodorization (H-WSD) (250 °C for 60 min). The removal rates of PAHs in L-ESD oil can be higher than those in conventional H-WSD oil, and the contents of 3-MCPDE and GE in L-ESD oil (140-180 °C for 60-100 min) ranged from 48.32 to 73.65 % and 50.49-69.90 %, respectively, in H-WSD oil due to the lower temperature of ethanol steam deodorization. These results indicate that L-ESD is beneficial in minimizing the contents of PAHs, 3-MCPDE and GE in vegetable oil.

Toxicology of 3-monochloropropane-1,2-diol and its esters: a narrative review

3-Monochloropropane-1,2-diol (3-MCPD) is a chiral molecule naturally existing as a racemic mixture of (R)- and (S)-enantiomers. It was thoroughly investigated during the 1970s as a male antifertility drug until research was abandoned because of the side effects observed in toxicity studies. More than 20 years later, 3-MCPD, both in the free form and esterified to the fatty acids, was detected in vegetable oil and discovered to be a widespread contaminant in different processed foods. This review summarises the main toxicological studies on 3-MCPD and its esters. Current knowledge shows that the kidney and reproductive system are the primary targets of 3-MCPD toxicity, followed by neurological and immune systems. Despite uncertainties, in vivo studies suggest that renal and reproductive toxicity is mediated by toxic metabolites, leading to inhibition of glycolysis and energy depletion. Few acute, short-term, and subchronic toxicity studies have investigated the 3-MCPD esters. The pattern of toxicity was similar to that of free 3-MCPD. Some evidence suggests that the toxicity of 3-MCPD diesters may be milder than 3-MCPD, likely because of an incomplete enzymatic hydrolysis in the equivalent free form in the gastrointestinal tract. Further research to clarify absorption, metabolism, and long-term toxicity of 3-MCPD esters would be pivotal to improve the risk assessment of these compounds via food.

Occurrence of glycidyl esters in infant formula products on the Canadian market between 2015 and 2019

Glycidyl fatty acid esters (GEs) are processing contaminants formed during refining steps of vegetable oils. 'In vivo' hydrolysis of GEs releases potentially carcinogenic and genotoxic glycidol (2,3-epoxy-1-propanol). Occurrence of GEs in vegetable oils used for infant formula manufacturing may pose a potential health concern for formula-fed infants. Refined oils are commonly used as the main fat ingredient in formula manufacturing. For this study, different infant formula products (powders, concentrates and ready-to-feed formula products) were purchased and analysed in 2015 (35 samples) and 2019 (33 samples). Seven individual GEs were analysed by LC-MS/MS via direct approach by stable isotope dilution analysis, and total bound glycidol concentrations were calculated. Concentrations of bound glycidol in reconstituted formula reached maxima of 40.3 ng/g in the 2015 samples and 31.5 ng/g in the samples collected in 2019, with respective means of 8.7 ng/g and 6.7 ng/g. The analysed bound glycidol concentrations are comparable with concentration ranges from other studies, but are higher than observed in studies from the European market. Temporal trend data show a reduction of bound glycidol concentrations in 2019. GE concentrations were compared across different manufacturers.

Deep-fat Frying Using Soybean Oil-based Diacylglycerol-Palm Olein Oil Blends: Thermo-oxidative Stability, 3-MCPDE and Glycidyl Ester Formation

Diacylglycerol (DAG) is commonly known as one of the precursors for the 3-monochloro-1,2-propanediol esters (3-MCPDE) and glycidyl esters (GE) formation. However, due to its health-promoting effects, its potential as alternative frying medium was examined. This study aimed to assess the frying performance of soybean oil-based diacylglycerol oil (DO) and its oil blends with palm olein (PO), in comparison with PO. Four different oil types (DO, PO, OB I (DO:PO, 1:1, w/w) and OB II (DO:PO, 1:2, w/w)) were used to fry potato chips for five consecutive days at 180℃. The formation of oxidation compounds, acylglycerol composition, 3-MCPDE and GE changes throughout the frying study were investigated. Both OB I and OB II exhibited lower oxidation compounds' formation rates than PO. Besides, significant (p < 0.05) reductions of 3-MCPDE and increments of GE levels were observed in all frying systems throughout the frying study. After 25 frying cycles, the 3-MCPDE levels in all frying oils were below 0.13 mg/kg, while the GE levels ranged from 1.51 mg/kg to 1.89 mg/kg. Despite the poorer oxidative stability of DO, its 3-MCPDE and GE levels were much lower compared to PO. In comparison to DO, the 3-MCPDE degradation and GE formation rates were enhanced and reduced, respectively with the blending of PO and DO. This study showed the potential of DO:PO oil blend in deep-fat frying application. With appropriate blending ratio of DO and PO, an alternative frying medium with enhanced nutritional value and oxidative stability could be developed.

Identification of Deoxynivalenol and Degradation Products during Maize Germ Oil Refining Process

Deoxynivalenol (DON) contamination in germs and germ oil is posing a serious threat to food and feed security. However, the transformation pathway, the distribution of DON, and its degradation products in edible oil refining have not yet been reported in detail. In this work, we systematically explored the variation of DON in maize germ oil during refining and demonstrated that the DON in germ oil can be effectively removed by refining, during which a part of DON was transferred to the wastes, and another section of DON was degraded during degumming and alkali refining. Moreover, the DON degradation product was identified to be norDON B by using the ultraviolet absorption spectrum, high-performance liquid chromatography (HPLC), ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF MS), and nuclear magnetic resonance (NMR) methods, and the degradation product was found to be distributed in waste products during oil refining. This study provides a scientific basis and useful reference for the production of non-mycotoxins edible oil by traditional refining.

Effects of Deodorization on the Formation of Processing Contaminants and Chemical Quality of Sunflower Oil

Tocopherols and phytosterols are generally considered to be nutritionally beneficial, and 3-Monochloropropane-1,2-diol esters (3-MCPD esters), glycidyl esters (GEs) and trans fatty acids (TFAs) are generally considered to be harmful. The high temperature deodorization step is when these harmful 3-MCPD esters, GEs and TFAs are generated. Knowing how deodorization conditions affect levels of these substances is essential for designing refining processes that will produce nutritious, high quality edible oils. This study analyzed the changes of these components of sunflower oil at different temperatures (210, 230, 250 and 270°C) and times (60, 80, 100 and 120 min) during deodorization. Our research found that during the whole deodorization process (including undeodorized sunflower oil), the contents of 3-MCPD esters, GEs and TFAs all progressively increased, from 0.47 to 11.18 mg/kg, 0.24 to 18.42 mg/kg and 0.062% to 0.698%, respectively. However, the deodorization process significantly decreased the levels of tocopherols (from 535.94 to 240.26 mg/kg) and phytosterols (from 2803.58 to 1864.34 mg/kg). Meanwhile, the retention ratios of total tocopherols and total phytosterols also decreased from 96.29% to 44.83% and 92.29% to 66.50%, respectively.

Encapsulation of CALB by nucleotide/metal ions coordination nanoparticles: highly selective catalysis of esterification while poor performance in glycerolysis reaction

BACKGROUND

Enzymatic esterification is attracting for particular high-acid oil deacidification. In this study, Candida antarctica lipase B (CALB) was encapsulated into a series of nucleotide-hybrid metal coordination polymers (CPs), which were constructed by guanosine 5'-monophosphate (GMP) and various metals.

RESULTS

We here found that, most of the present CPs encapsulated CALB (CALB@CPs) samples were highly selective for esterification while poor in glycerolysis reaction. They exhibited quite poor performance in glycerolysis, with triacylglycerols (TAGs) conversion lower than 5%, despite this considerable enzymatic hydrolysis activities were observed. However, they (most of them) showed good performance in esterification of fatty acids and glycerol for TAG synthesis. In addition, the GMP/Tb (CPs constructed by GMP and Tb³⁺ ) encapsulated CALB (CALB@GMP/Tb) transformed over 98% of oleic acid into glycerides in the high-acid oil deacidification process, and TAG content from 87 to 89% was obtained. Moreover, the CALB@GMP/Tb showed good reusability in the esterification system.

CONCLUSION

The present CALB@CPs samples are selective for esterification and suitable for high-acid oils deacidification. This work provides a new system for enzymatic selectivity improvement study. © 2021 Society of Chemical Industry.

Effects of Methyl Cellulose and Soybean Protein Isolate Coating on Amount of Oil and Chemical Hazards in Chinese Fried Dough Cake

ABSTRACT

Fat-related diseases and chemical hazards produced during the frying process pose a major threat to human health. Coatings have been used as a practical method to reduce the amount of oil and chemical hazards associated with fried foods. Methyl cellulose (MC) and soy protein isolate were used as coating materials to pretreat Chinese fried dough cake (CFDC) before frying. The 1.5% MC concentration was the best choice for coating to simultaneously lower oil and chemical hazards in CFDC. The CFDC prepared using 1.5% MC had 11.3% oil, 73.70 μg/kg acrylamide, 0.15 mg KOH/100 kg acid, 8.54 mmol/kg peroxide, p-anisidine value of 6.36, 0.36 μg/g malondialdehyde, 0.13 μg/g 4-hydroxy-2-(E)-hexenal (HHE), 0.51 μg/g 4-hydroxy-2-(E)-nonenal (HNE), and 4,272 μg/kg glycidyl ester. In contrast, the uncoated CFDC had 19.2% oil, 117.55 μg/kg acrylamide, 0.25 mg KOH/100 kg acid, 14.40 mmol/kg peroxide, p-anisidine value of 9.76, 0.63 μg/g malondialdehyde, 0.23 μg/g HHE, 0.86 μg/g HNE, and 5,758 μg/kg glycidyl ester. MC and soy protein isolate enhanced the oil barrier of the coating film, which effectively reduced the heat transfer coefficients, oil transfer, oil oxidation, and chemical hazards in the CFDC. Our work on this edible coating contributes to methods for control of oil and chemical hazards in fried foods.

HIGHLIGHTS

A summary of 2-, 3-MCPD esters and glycidyl ester occurrence during frying and baking processes

Monochloropropanediol (MCPD) esters and glycidyl esters (GE) are the process contaminants found in frying and baking, except the refining process. The free form MCPD and glycidol are released from their parent esters via lipase hydrolysis while they are carcinogen and genotoxic carcinogen, respectively. MCPD esters and GE are formed endogenously during vegetable oil refining process. Then, their concentration were experimented during subsequent food processing methods, especially frying and baking. This review discussed the occurrence of 2-, 3-MCPD esters and GE during frying and baking processes. Process temperature, process duration, presence of precursors, and their combined effects are highly related to MCPD esters and GE formations. An elevated temperature and processing time can increase the formation of these contaminants until an optimum rate and then followed by the decomposition. Also, other factors such as the presence of chloride ions, moisture, and partial acylglycerol can further facilitate MCPD esters and/or GE formation.

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Frying and baking trigger formation of MCPD esters and GE.

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MCPD esters and GE are formed endogenously during refining process.

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The concentration of MCPD esters and GE elevated during thermal processing.

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Temperature, process duration, and precursors cause MCPD esters and GE formations.

The inhibitory effects of sesamol and sesamolin on the glycidyl esters formation during deodorization of vegetables oils

BACKGROUND

Glycidyl esters (GEs) have attracted worldwide attention for their potential harm to human health. The GEs in edible oils mainly form during the deodorization of the oil refining processes. We used sesamol and sesamolin to inhibit the formation of GEs in model corn oil (MCO), model palm oil (MPO) and model rice bran oil (MRO) during a deodorization process.

RESULTS

The results showed that, in the three model oils, the total GE content was in the following order from highest to lowest: MRO (1437.98 μg kg^-1 ) > MPO (388.64 μg kg^-1 ) > MCO (314.81 μg kg^-1 ). The inhibitory effect of the three antioxidants on the formation of GEs in the MCO was in the following order from strongest to weakest: tert-butylhydroquinone (TBHQ) > sesamol > sesamolin.

CONCLUSION

When the mass percentage of sesamol was 0.05%, its inhibition percentage on GEs was close to the inhibition percentage of 0.02% added TBHQ. The present study provides a foundation for understanding how to inhibit the formation of GEs in oils by adding sesamol during the deodorization process.

Occurrence of thermally induced glycidyl esters and 3-monochloropropane-1,2-diol esters in refined oils and pressed oils manufactured by different processes and associated with human health risks in Taiwan

Glycidyl esters (GEs) and 3-monochloropropane-1,2-diol esters (3-MCPDEs) are heat-induced contaminants mainly formed during oil refining. Information on the occurrence of these contaminants in pressed oils is still limited. In this study, 16 oilseeds pressed with a screw press and a hydraulic press had extremely low concentrations of GEs and 3-MCPDEs. Seed-roasting at high temperatures was the principal factor that significantly increased contents of GEs and 3-MCPDEs in pressed oils, in which higher precursor levels were observed. Occurrence data of GE and 3-MCPDE concentrations in refined oils (n = 25) and pressed oils (n = 26) marketed in Taiwan showed that hot-pressed oils had higher concentrations than their cold-pressed counterparts, and average concentrations of refined oils were > 10-fold higher than those of pressed oils. Risk assessment using the margin of exposure (MOE) approach indicated the presence of GEs in edible oils was of concern for food safety, especially for people who frequently use refined oils.

First Determination of Glycidyl Ester Species in Edible Oils by Reverse-Phase Ultra-Performance Liquid Chromatography Coupled with an Evaporative Light-Scattering Detector

In this work, a new ultra-performance liquid chromatograph-evaporative light-scattering detector (UPLC-ELSD) method for quantitation of glycidyl esters (GE) contents in edible oils is presented. The method features complete separation of five GE species within 20 min by a C18 column and gradient elution with a mobile phase consisting of 85% and 2.5% methanol aqueous solutions. The coefficients of regression (R²) were all ≥0.9999 for the linear-quadratic regression curves of GE species in a concentration range of 5~80 μg/mL. The intraday and interday recoveries (%) of GE species in solvent were in a range of 81.3~107.3%, and the intraday and interday coefficients of variation (CVs, %) were all ≤8.6%. The average recovery (%) of GE species spiked in extra-virgin olive oil samples ranged from 88.3~107.8% and the intermediate precision (CV, %) of ≤14% indicated acceptable accuracy and precision. The method exhibited limit of quantification (LOQ) for each GE species (0.6 μg glycidol equivalents/g oil). The method was applied to determine GE concentrations of six commercial oil samples, and total glycidol equivalents were consistent with data obtained by GC-MS method. This UPLC-ELSD method could be adopted for precursory screening and research purposes to improve food safety when MS detectors are unavailable.

Chloride-mediated co-formation of 3-monochloropropanediol esters and glycidyl esters in both model vegetable oils and chemical model systems

3-Monochloropropanediol esters (3-MCPDEs) and glycidyl esters (GEs) with high toxicity have drawn global concerns due to their widespread occurrence in refined oils and oil-based foods. The effect mechanisms of organic chlorine compound lindane, inorganic chlorine compounds tetra-n-butylammonium chloride (TBAC) and sodium chloride (NaCl) on the formation of 3-MCPDEs and GEs were investigated in model oils and chemical models at 240 °C. Results showed that 3-MCPDEs contents increased with the addition of lindane and TBAC, whereas, surprisingly, GEs presented the same tendency as the results of 3-MCPDEs. This suggested that although chlorine compounds were not involved in the formation reaction of GEs, they could also promote GEs formation. Chemical model experiments confirmed that the presence of chlorine compounds led to the transformation of GEs to 3-MCPDEs and conversely 3-MCPDEs could also transform to GEs. The latter transformation rate from 3-MCPDEs to GEs was higher than the former, which might account for the fact that chlorine compounds promoted GEs formation. Additionally, it was also observed that solid NaCl did not induce the increase of 3-MCPDEs and GEs levels in chemical models, suggesting that the chlorine in NaCl, different from lindane and TBAC, was not available for 3-MCPDEs formation. The present findings give novel insights into the interactions between 3-MCPDEs and GEs formation mechanisms, which offer the theoretical basis for efficient and simultaneous inhibition of 3-MCPDEs and GEs.

Kinetic Study and Degradation Mechanism of Glycidyl Esters in both Palm Oil and Chemical Models during High-Temperature Heating

A kinetic model for glycidyl ester (GE) formation in both palm oil and chemical models during high-temperature heating was built to investigate the formation and degradation mechanisms of GEs in refined palm oil. The results showed that the formation and degradation of GEs followed pseudo-first-order reactions, and the rate constants of reaction kinetics followed the Arrhenius equation. The estimated activation energy of the GE degradation reaction (12.87 kJ/mol) was significantly lower than that of the GE formation reaction (34.58 kJ/mol), suggesting that GE degradation occurred more readily than formation. The Fourier transform infrared (FTIR) band intensities of epoxy and ester carboxyl groups decreased over heating time, while no band assigned to the cyclic acyloxonium group was found. Furthermore, no 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-cyclic acyloxonium radical adduct was detected by quadrupole time-of-flight mass spectrometry (Q-TOF-MS). The above findings indicated that GEs were decomposed, fatty acid was also liberated, and GE degradation did not involve a cyclic acyloxonium intermediate. GEs were primarily decomposed into monoacylglycerol via ring-opening reaction during heating followed by fatty acid and glycerol via hydrolysis reaction.

Effective physical refining for the mitigation of processing contaminants in palm oil at pilot scale

This study aimed to develop a mitigation strategy for the formation of 2-monochloropropane-1,3-diol esters (2-MCPDE), 3-monochloropropane-1,2-diol esters (3-MCPDE), and glycidol fatty acid esters (GE) during palm oil refining. Single physical refining was the starting point (the control) for this study. Experimental treatments including a double refining repeating the entire single refining process (T1), double refining with a high-low deodorization temperature (T2), and double deodorization (T3) with similar temperature settings as T2 were performed. Compared with the control experiment, T2 successfully reduced the formation of GE by 87%; in particular, the second degumming and bleaching were crucial for eliminating GE. Both 2- and 3-MCPDE were formed prior to the deodorization process in all treatments. MCPDE concentrations remained stable throughout the refining process and, hence, they require a different mitigation approach as compared to GE. These results provide useful insights which can directly be implemented by the oil industry.

Occurrence of MCPD and glycidyl fatty acid esters in standard and specialised infant formula in Denmark

Standard infant formula and specialised infant formula for medical purposes in Denmark (n = 42) were assessed for the levels of 2-MCPDEs, 3-MCPDEs, and GEs. Similar concentrations of GEs were observed in both standard and specialised powder infant formula at around 11.5 µg/kg. For 2-MCPDEs and 3-MCPDEs, significantly higher concentrations were observed in specialised products (18.0 and 49.8 µg/kg, respectively) in comparison with the standard ones (11.8 and 31.0 µg/kg, respectively). The concentration profiles also revealed discrepancies in MCPDEs and GEs concentrations not only between different manufacturers but also in terms of infant formula variety. For instance, the hypoallergenic powder formula showed twice as much MCPDEs as the normal formula variety. Exposure estimation using average contaminant concentrations in each variety suggested no potential risk of 3-MCPDEs and GEs intake for Danish infants via infant formula consumption. However, special attention is required for a few specific products where risks might occur in terms of 3-MCPDEs and/or GEs consumption.

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.

Levels of the hemoglobin adduct N-(2,3-Dihydroxypropyl)-valine in cord and maternal blood: Prenatal transfer of glycidol in the ENVIRONAGE birth cohort

BACKGROUND

Glycidol, a probable human carcinogen, is a reactive chemical released in the gastrointestinal tract from glycidyl fatty acid esters, which are heat-induced dietary contaminants.

OBJECTIVES

To investigate the prenatal transfer of glycidol, a specific hemoglobin adduct was measured as a biomarker for internal glycidol exposure in paired cord and maternal blood samples.

METHODS

In 100 mother-newborn pairs from the Belgian ENVIRONAGE (ENVIRonmental influence ON AGEing in early life) birth cohort, we studied the correlation between levels of the glycidol-derived hemoglobin adduct N-(2,3-dihydroxypropyl)-valine (2,3-diHOPr-Val) in paired cord and maternal blood samples. The adduct levels were determined after cleavage with a modified Edman degradation by using ultra-high performance liquid chromatography-tandem mass spectrometry and an isotope-labeled reference standard.

RESULTS

2,3-DiHOPr-Val was detectable in all 100 maternal blood samples and in 96 cord blood samples (LOD =0.5 pmol 2,3-diHOPr-Val/g hemoglobin), with medians of 5.4 (range: 2.3-29.2) and 1.6 (range: LOD - 8.9) pmol/g hemoglobin), respectively. In blood samples of mothers who smoked during pregnancy and in the cord blood samples of their newborns (n = 6), the median 2,3-diHOPr-Val levels were 16.7 (range: 6.4-29.2) and 6.2 (range: LOD - 8.6) pmol/g hemoglobin, respectively. The median ratio of 2,3-diHOPr-Val levels of cord to maternal blood was 0.35 (range: 0.19-1.14) (n = 49). The Spearman correlation coefficient between 2,3-diHOPr-Val levels in cord and maternal blood samples was 0.63 (p < 0.001) among all mother-newborn pairs and 0.59 (p < 0.001) among mother-newborn pairs of non-smoking mothers.

DISCUSSION

Maternal data confirm widespread exposure to glycidol, also in non-smokers. Neonatal levels indicate prenatal exposure to glycidol, due to an obviously relatively unhindered passive transfer through the placental barrier. Possible health effects of fetal (and postnatal) glycidol exposure in children may be addressed in epidemiological studies.

Zearalenone Removal from Corn Oil by an Enzymatic Strategy

The estrogen-like mycotoxin zearalenone (ZEN) is one of the most widely distributed contaminants especially in maize and its commodities, such as corn oil. ZEN degrading enzymes possess the potential for counteracting the negative effect of ZEN and its associated high safety risk in corn oil. Herein, we targeted enhancing the secretion of ZEN degrading enzyme by Pichia pastoris through constructing an expression plasmid containing three optimized expression cassettes of zlhy-6 codon and signal peptides. Further, we explored various parameters of enzymatic detoxification in neutralized oil and analyzed tocopherols and sterols losses in the corn oil. In addition, the distribution of degraded products was demonstrated as well by Agilent 6510 Quadrupole Time-of-Flight mass spectrometry. P. pastoris GSZ with the glucoamylase signal was observed with the highest ZLHY-6 secretion yield of 0.39 mg/mL. During the refining of corn oil, ZEN in the crude oil was reduced from 1257.3 to 13 µg/kg (3.69% residual) after neutralization and enzymatic detoxification. Compared with the neutralized oil, no significant difference in the total tocopherols and sterols contents was detected after enzymatic detoxification. Finally, the degraded products were found to be entirely eliminated by washing. This study presents an enzymatic strategy for efficient and safe ZEN removal with relatively low nutrient loss, which provides an important basis for further application of enzymatic ZEN elimination in the industrial process of corn oil production.