This study sought to analyze the oxidative products [acid value (AV), free fatty acids (FFA), conjugated dienoic acid (CDA), p-anisidine value (p-AV), antioxidant-prooxidant balance (APB) value] and toxic compounds [3-monochloropropane diol (3-MCPD), glycidyl ester (GE)] in edible oils after deep-frying. The deep-frying edible oils evaluated herein included soybean oil (S), palm oil (P), canola oil (C), grape seed oil (G), and a 1:1 blend (SC, SG, PC, PG, and CG). As frying time increased, the level of AV in PC, total FFA contents in CG, and p-AV in CG significantly increased up to 200%, 45.5%, and 410.5%, respectively (p < 0.05). The levels of 3-MCPD, and GE were 0.81-6.28 µg/mL and 0.14-2.84 µg/mL, respectively. The levels of 3-MCPD, GE, CDA, and APB changed significantly as frying time increased. Analysis of the correlation between oxidation products and toxic compounds indicated that the contents of 3-MCPD and palmitic acid were positively correlated.
UNASSIGNED: The online version contains supplementary material available at 10.1007/s10068-023-01494-9.

This study presents a method based on acid transesterification and the purification by solid-phase extraction (SPE) coupled with gas chromatography-tandem mass spectrometry for quantifying 3- and 2-monochloropropanediol esters (3-MCPDE, 2-MCPDE) and glycidyl esters (GE) in nutritional foods. The fat was extracted by liquid-liquid extraction with petroleum ether and diethyl ether after the sample was hydrolysed with ammonia. Then the extract was purified by a SPE cartridge filled with the aminopropyl sorbents. It was demonstrated that the optimal elution volume for 3-MCPDE, 2-MCPDE and GE greatly depended on the sample matrix and varied from 6 to 12 mL for four different kinds of food matrices. All three analytes in the sample solution could be fully collected in the first 10-12 mL of eluate. By this way, monoacylglycerols commonly present in the samples were fully removed. Therefore, the overestimation of GE quantification was effectively eliminated. The modified analytical procedure was fully validated in a single laboratory and has been recommended as a Chinese Food Safety National Standard. In addition, two derivatisation agents, heptafluorobutyrylimidazole and phenylboronic acid, were proved to be equivalent in method accuracy and precision for the quantification of three analytes.

The presence of 3-monochloropropane-1,2 diol ester (3-MCPDE) and glycidyl ester (GE) in processed palm oils is of concern, as these oils are widely used for edible purposes. The mitigation method studied here optimizes the removal of chloride through water washing of crude palm oil (CPO), to limit the formation of 3-MCPDE. The contaminant removal obtained via washing CPO supports the quantitative findings. By utilizing 5% water in the washing step, water-soluble chlorides in CPO are removed by up to 76%, resulting in a 71% reduction of 3-MCPDE to within statutory limits. In this study, a linear correlation was developed between the chloride and the corresponding 3-MCPDE with a correlation coefficient (R2) of 0.99. Using the correlations, 1.0 mg/kg of 3-MCPDE in refined, bleached and deodorized palm oil (RBDPO) will be obtained from CPO with 1.2 mg/kg chloride with 7% wash water usage. The study also showed minor GE reduction between 7 and 11% was attained after water washing.

Palm oil is a vegetable oil that is widely used for cooking and deep-frying because of its affordability. However, repeatedly heated palm oil is also prone to oxidation due to its significant content of unsaturated fatty acids and other chemical toxicants such as glycidyl esters and 3-monochloropropane-1,2-diol (3-MCPD). Initially, the physicochemical properties such as colour, viscosity, peroxide, p-anisidine and total oxidation (TOTOX) of periodically heated palm oil were investigated. Chemical profiling and fingerprinting of six different brands of palm cooking oil during heating cycles between 90 and 360 min were conducted using Fourier transform infrared (FTIR) and 1H Nuclear Magnetic Resonance (NMR) metabolomics. In addition, the multivariate analysis was employed to evaluate the 1H NMR spectroscopic pattern of repeatedly heated palm oil with the corresponding physicochemical properties. The FTIR metabolomics showed significant different of the chemical fingerprinting subjected to heating duration, which in agreement with the result of 1H NMR metabolomics. Partial least squares (PLS) model revealed that most of the physicochemical properties of periodically heated palm oil are positively correlated (R2 values of 0.98-0.99) to their spectroscopic pattern. Based on the findings, the color of the oils darkened with increased heating time. The peroxide value (PV), p-anisidine value (p-AnV), and total oxidation (TOTOX) values increased significantly due to degradation of unsaturated compounds and oxidation products formed. We identified targeted metabolites (probable carcinogens) such as 3-monochloropropane-1,2-diol (3-MCPD) and glycidyl ester (GE), indicating the conversion of 3-MCPD to GE in repeatedly heated oils based on PCA and OPLSDA models. Our correlation analysis of NMR and physicochemical properties has shown that the conversion of 3-MCPD to GE was significantly increased from 180 to 360 min cooking time. The combination spectroscopic techniques with physicochemical properties are a reliable and robust methods to evaluate the characteristics, stability and chemical\'s structure changes of periodically heated palm oil, which may contribute to probable carcinogens development. This study has proven that combination of NMR and physicochemical analysis may predict the formation of the probable carcinogens of heated cooking oil over time which emphasizing the need to avoid certain heating cycles to mitigate formation of probable carcinogens during cooking process.

Esters of 2- and 3-monochloropropanediol (2-MCPDE, 3-MCPDE) and glycidol (GE) are regarded as process contaminants that are found in refined vegetable oils and oil-based foods. Since glycerol is produced during fat splitting, saponification and biodiesel production, it is important to have methods for determining contaminants that might be formed during these processes. Due to the use of glycerol as a food additive, data on the presence of compounds of toxicological concern, including 3-MCPD, are of interest. This study focuses on modifying the indirect analysis of 2-MCPDE, 3-MCPDE and GE using GC-MS based on the AOCS Official Method Cd 29a-13, validating the modified method, and quantifying 2-MCPDE, 3-MCPDE and GE in glycerol. The AOCS Cd 29a-13 method was modified at the initial stage of sample preparation in which the targeted esters were extracted from glycerol by vortex-assisted extraction before sample analysis. This modification was performed based on the polarity of all compounds involved. The calibration functions for all analytes were fitted to linear regression with R2 above 0.99. Limits of detection (LOD) 0.02, 0.01 and 0.02 mg kg-1 were obtained for 2-MCPDE, 3-MCPDE and GE, respectively. Spiked glycerol with 3-MCPDE and 2-MCPDE (0.25, 0.51 and 1.01 mg kg-1) and GE (0.58, 1.16 and 2.32 mg kg-1) were used for recovery and precision measurements. Recoveries of 100-108%, 101-103%, and 93-99% were obtained for 2-MCPDE, 3-MCPDE and GE, respectively. Acceptable precision levels with relative standard deviations ranged from 3.3% to 8.3% were obtained for repeatability and intermediate precision. The validated method was successfully applied for the analysis of the target compounds in refined glycerol from commercial plants, which showed that 2-MCPDE, 3-MCPDE and GE levels in the analysed samples were below the detection limit.

The rising concern about the presence of 3-monochloropropane 1,2 diol ester (3-MCPDE) and glycidyl ester (GE) in food has prompted much research to be conducted. Some process modifications and the use of specific chemicals have been employed to mitigate both 3-MCPDE and GE. Alkalisation using NaOH, KOH, alkali metals or alkaline earth metals and post sparging with steam or ethanol and short path distillation have shown simultaneous mitigation of 51-91% in 3-MCPDE and of 13-99% in GE, both contaminants achieved below 1000 µg/kg. Some of the mitigation methods have resulted in undesirable deterioration in other parameters of the refined oil. When the processed oil is used in food processing, it results in changes to 3-MCPDE and GE. Repeated deep frying above 170 °C in the presence of NaCl and baking at 200 °C with flavouring (dried garlic and onion), resulted in increased 3-MCPDE. Repeated frying in the presence of antioxidants (TBHQ, rosemary and phenolics) decreased 3-MCPDE in processed food. The GE content in foods tends to decline with time, indicating instability of GE\'s epoxide ring.

Esters of 2-monochloropropane-1,2-diol (2-MCPD), 3- monochloropropane-1,2-diol (3-MCPD), and glycidol are present in infant formulas, follow-on foods and similar compositions. They arise mainly from the vegetable oil content and may cause harmful effects in consumers. The contents of these substances in formulas were determined indirectly by converting the esters to the free form, followed by derivatization and analysis by gas chromatography-tandem mass spectrometry (GC-MS/MS). The validation results demonstrate that the method had sufficient specificity and adequate accuracy. The limits of detection (LOD) and limits of quantification (LOQ) for each of 2-MCPDE, 3-MCPDE, and GE were 1.5 and 5 µg/kg, respectively. Formula intake by children up to 36 months of age was surveyed, and the data was used to assess the risks due to 3-MCPD esters (3-MCPDE) and glycidyl esters (GE). The mean exposure dose of 3-MCPDE for different age groups ranged from 0.51 to 1.13 µg/kg bw per day. The corresponding mean GE exposure ranged from 0.031 to 0.069 µg/kg bw per day. Neither mean values nor the percentile 95% values of 3-MCPDE exposure doses exceed the recommended provisional maximum tolerable daily intake (PMTDI).

With the prevalence of edible diacylglycerol (DAG) oil, which is beneficial to human, the generation of 3-monochloropropanediol esters (3-MCPDE) and glycidyl esters (GE) as well as the stability of physical properties during heat-induced processing still need to be explored. In this study, the experiment used olive-based edible oil with different contents of DAG (40, 60, and 80%) to make crackers and fry chicken. They were heated at 160 and 180 °C to determine the changes in 3-MCPDE and GE, the crackers’ hardness and gumminess, and the physical properties of the oil. During baking and frying, 3-MCPDE decreased, while the content of GE slightly increased with the prolonged heating duration. Finally, 3-MCPDE and GE were lower than 1.25 mg/kg and 1.00 mg/kg, respectively. The AV increased proportionally as duration increased and POV was below 0.30 g/100 g. In general, the changes in 3-MCPDE and GE were related to the heating temperature and duration, and not significantly (p > 0.05) related to the content of DAG.

In this study, the effects of the deodorization process on the interconversion between 3-monochloro-1,2-propanediol ester (3-MCPDE) and glycidyl ester (GE) using 3-MCPDE or GE standards containing deuterium-labeled palmitic acid (*P), oleic acid (*O), or linoleic acid (*L) were examined. Deuterium-labeled 3-MCPDE or GE was added to palm oil then deodorized at 250 °C for 20, 40, or 60 min. In the 3-MCPDE-spiked palm oil, the deuterium-labeled 3-MCPDE content decreased with deodorization time. Moreover, GE containing *P or *O was detected, but there was no GE containing *L in the 3-MCPDE-spiked palm oil. In the GE-spiked oil, GE containing *O or *L decreased with deodorization time, but the content of GE containing *P did not change over the time. Furthermore, deuterium-labeled 3-MCPDE was not detected in the GE-spiked oil. These results suggest that 3-MCPDE is converted into GE and that fatty acid species bound to 3-MCPDE or GE may affect their interconversion.

Diacylglycerol (DAG) is commonly known as one of the precursors for 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) formation. Besides, 3-MCPDE and GE are heat-induced contaminants which can be formed in fat-containing baked products during the baking process. This study attempted to replace the conventional palm-based shortening (SH) with a healthier fat, namely soybean oil-based diacylglycerol stearin (SDAG) in producing biscuits. The effects of different baking temperatures (200, 210 and 220 °C) and SDAG:SH fat blend ratios (0:100, 60:40 (D64S), 80:20 (D82S), 100:0, w/w) towards the biscuits\' physical properties were evaluated. Moreover, the oxidative stability, 3-MCPDPE and GE formation in the fats extracted from the biscuits were also investigated. SDAG-produced biscuit showed slight reductions in the spread ratio compared to the SH-produced biscuit. The elevated baking temperatures resulted in biscuits with increased hardness and low moisture content. Pure SDAG and the other fat blends exhibited significant (p < 0.05) poorer oxidative stability than SH. However, D64S was found to be more oxidative stable compared to SDAG and D82S. The D64S fat blend exhibited the lowest 3-MCPDE and GE formation rates among all fat samples with the increasing baking temperatures. Furthermore, the amount of 3-MCPDE and GE detected in the fats extracted from the biscuits baked at highest temperature (220 °C) were still within the safety limit. In overall, better quality biscuits were produced when lower baking temperature (200 °C) was used as all biscuits baked with different fats showed similar textural properties (hardness and cohesiveness), higher oxidative stability and lower formation of 3-MCPDE and GE compared to biscuits baked at higher temperatures. The findings justified the potential of D64S fat blend in replacing the conventional SH in producing healthier biscuits.