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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.

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., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In the present study, the formation mechanisms of glycidyl fatty acid esters (GEs) were investigated both in real edible oils (soybean oil, camellia oil, and palm oil) during laboratory-scale preparation and refining and in chemical model (1,2-dipalmitin (DPG) and 1-monopalmitin (MPG)) during high temperature exposure (160-260 °C under nitrogen). The formation process of GEs in the chemical model was monitored using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The results showed that the roasting and pressing process could produce certain amounts of GEs that were much lower than that produced in the deodorization process. GE contents in edible oils increased continuously and significantly with increasing deodorization time below 200 °C. However, when the temperature exceeded 200 °C, GE contents sharply increased in 1-2 h followed by a gradual decrease, which could verify a simultaneous formation and degradation of GEs at high temperature. In addition, it was also found that the presence of acylglycerol (DAGs and MAGs) could significantly increase the formation yield of GEs both in real edible oils and in chemical model. Compared with DAGs, moreover, MAGs displayed a higher formation capacity but substantially lower contribution to GE formation due to their low contents in edible oils. In situ ATR-FTIR spectroscopic evidence showed that cyclic acyloxonium ion intermediate was formed during GE formation derived from DPG and MPG in chemical model heated at 200 °C.

Glycidyl ester (GE) is a class of food‐processing contaminant widely found in edible oil‐based food products. Adding antioxidants can inhibit the formation of GE in deep frying oil. In this research, sesamol was adopted to replace the unsafe chemically synthesized antioxidants, tert‐butylhydroquinone (TBHQ), to inhibit the formation of GE in deep frying palm oil (PO). The result showed that the inhibitory capacity of sesamol and TBHQ to GE formation in PO was of the following ranking: 0.10%sesamol >0.02%TBHQ >0.06%sesamol >0.02%sesamol. Acid value, peroxide value, p‐anisidine value, and total polar compounds of PO were also determined, which indicated that sesamol could inhibit the formation of GEs by inhibiting oil hydrolysis and oxidation. Fourier‐transform infrared spectroscopy also demonstrated that sesamol could inhibit the formation of GEs. This work will offer a better understanding on the final control of GE in oil frying process with sesamol. Novelty impact statement: The inhibitory capacity of sesamol to the glycidyl ester formation is weaker than that of TBHQ.Sesamol can inhibit glycidyl ester by inhibiting oil hydrolysis and oxidation in palm oil frying process.Increasing sesamol concentration to 0.10% is enough to inhibit glycidyl ester. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Summary: This research investigated the effect of carnosic acid (CA), tert‐butyl hydroquinone (TBHQ), sesamol (SL) and L‐ascorbyl palmitate (AP) on the inhibition of glycidyl esters (GEs) and oxidation parameter changes in rice bran oil (RBO) during heat processing. The electron spin resonance (ESR) analysis showed that the free radical scavenging ability of them was ranked as CA > TBHQ > SL > AP. With the addition of CA, TBHQ, SL and AP (0.6 g kg−1), the GEs content was reduced significantly from 987.98 ± 8.45 to 283.87 ± 4.78, 303.21 ± 4.38, 440.52 ± 3.82 and 500.55 ± 2.99 μg kg−1, respectively. All four free radical scavengers had the highest inhibitory effect on C18:2‐GE, followed by C18:1‐GE and C16:0‐GE. Moreover, the free radical scavengers were also effective to inhibit oil oxidation. Overall, the natural‐free radical scavenger may be a promising candidate to mitigate GE formation and oil oxidation due to its effectiveness and safety. [ABSTRACT FROM AUTHOR]

Glycidyl ester (GE) has attracted worldwide attention due to its potential harm to human health. The GE in edible oil forms during the deodorization process of the oil refining, where antioxidants are used to inhibit its formation. To replace unsafe conventional synthetic antioxidants with natural antioxidants, sesame oil (SO) was used to inhibit the formation of GE in corn oil (CO), palm oil (PO), and rice bran oil (RO) during the deodorization process. The results showed that the content of GE in SO, CO, PO and RO followed the decreasing order of RO (1395.88 μg/kg) > PO (376.84 μg/kg) > CO (303.24 μg/kg) > SO (133.19 μg/kg). The concentration of diacylglycerol (DAG) in SO, CO, PO and RO followed the decreasing order of RO (11.64%) > PO (7.56%) > CO (4.11%) > SO (2.59%). The content of GE in oil could be affected by at least three factors: (i) unsaturated fatty acids could promote the formation of GE in oil; (ii) antioxidants in oil could inhibit the formation of GE by scavenging free radicals; and (iii) DAG, as a precursor, could lead to the formation of GE. This result suggested that SO could inhibit the formation of GE in CO, PO and RO. This indicated that when SO was added at 50%, its inhibitory effect was equivalent to that of tert-butylhydroquinone added at 0.02%. [ABSTRACT FROM AUTHOR]