Optical isomers of chloropropanediols: mechanisms of their formation and decomposition in protein hydrolysates

Velı́šek, J.; Doležal, Marek; Crews, Colin; Dvořák, Tomáš

doi:10.17221/3527-cjfs

Cited by 37 publications

(23 citation statements)

References 20 publications

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“…The other two proposals postulated the formation of an intermediate acyl oxonium or an epoxide before nucleophilic attack by the chloride ions. Our study showing the effect of acidity on the formation supports the direct nucleophilic substitution mechanism, which is considered as a plausible mechanism [22][23][24].…”

Section: Resultssupporting

confidence: 76%

Effects of Degumming and Bleaching on 3‐MCPD Esters Formation During Physical Refining

Ramli

Siew

Ibrahim

et al. 2011

J Americ Oil Chem Soc

110

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Crude palm oil (CPO) was physically refined in a 200-kg batch pilot refining plant. A study of the possible role of degumming and bleaching steps in the refining process for a possible critical role in the formation of 3-chloropropane-1,2-diol (3-MCPD) esters was evaluated. For the degumming step, different percentages of phosphoric acid (0.02-0.1%) as well as water degumming (2.0%) were carried out. Six different types of bleaching clays, mainly natural and acid activated clays were used for bleaching process at a fixed dose of 1.0%. Deodorization of the bleached oils was performed at 260°C for 90 min. Analyses showed that 3-MCPD esters were not detected in the CPO. Phosphoric acid degumming (0.1%) in combination with acid activated clays produced the highest levels (3.89 ppm) of 3-MCPD esters in the refined (RBD) oil. The esters were at the lowest levels (0.25 ppm) when the oil was water degummed and bleached with natural bleaching clays. However, the refined oil qualities were slightly compromised. Good correlation of 0.9759 and 0.9351 was obtained when concentration of the esters was plotted against acidity of the bleaching earths for the respective acid and water degumming processes. The findings revealed the contribution of acidic conditions on the higher formation of 3-MCPD esters. In order to lower the esters formation, it is important to reduce acid dosage based on the crude oil qualities or to find alternatives to acid degumming process. Neutralization of the acidity prior to deodorization was effective in reducing the formation of 3-MCPD esters.

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Section: Resultssupporting

confidence: 76%

Effects of Degumming and Bleaching on 3‐MCPD Esters Formation During Physical Refining

Ramli

Siew

Ibrahim

et al. 2011

J Americ Oil Chem Soc

110

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“…Presently, there are four proposed mechanisms (Fig. 3) all involving S N 2 nucleophilic attack by chloride ions, distinguished from each other based on either the nature of the substrate or the leaving group 8, 23–26. Two of the proposed mechanisms involve direct nucleophilic attack by the chloride ion at the glycerol carbon atoms carrying either an ester group (pathway a) or a protonated hydroxyl group (pathway b).…”

Section: Process‐induced Chloropropanol Estersmentioning

confidence: 99%

What do we know about the molecular mechanism of 3‐MCPD ester formation?

Rahn

Yaylayan

2011

Euro J Lipid Sci & Tech

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The 3-monochloropropane-1,2-diol (3-MCPD) esters belong to a group of well known process-induced contaminants derived from mono-and di-chlorinated glycerols. The 3-MCPD was first identified in 1978 in acid-hydrolysed vegetable proteins and its corresponding esters in 1980 and since their discovery almost 30 years later the exact mechanism of their formation is still unknown. The recent renewed interest in their formation mechanism can be attributed to the realization that the ester content in real food systems often exceeds that of free 3-MCPD content by many orders of magnitude. Presently, there are four proposed mechanisms all involving S N 2 nucleophilic attack by chloride ions but differing from each other based on either the nature of the substrate or the leaving group. Two of the proposed mechanisms involve direct nucleophilic attack by the chloride ion at the glycerol carbon atoms carrying either an ester group or a protonated hydroxyl group. The other two pathways propose the formation of reactive intermediates such as acyloxonium ion or an epoxide ring in the form of glycidol prior to the nucleophilic attack by chloride ions.

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“…The presence of these compounds in foods is of concern because the results of toxicological studies showed that they could endanger human health (EC 2001, BfR 2007, EFSA 2008, Joint FAO/WHO 2008). Velíšek et al (1979Velíšek et al ( , 2002 and Davídek et al (1982) were the first to report the discovery of CPD esters together with other chloropropanols in acid hydrolysed proteins (Velíšek et al 1980;Velíšek 2009) and in a cultivar of processed foods . The most important precursors of chloropropanol esters identified in foods are fats derived from glycerol (glycerolipids) such as triacylglycerols, partial acylglycerols, glycerophospholipids, and chlorides either naturally present or added as sodium chloride.…”

mentioning

confidence: 99%

3-Chloropropane-1,2-diol fatty acid esters in potato products

Ilko¹,

Zelinková²,

Doležal³

et al. 2011

Czech J. Food Sci.

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Ilko V., Zelinková Z., Doležal M., Velíšek J. (2011): 3-Chloropropane-1,2-diol fatty acid esters in potato products. Czech J. Food Sci., 29: 411-419.The levels of 3-chloropropane-1,2-diol (3-CPD) and fatty acid esters in raw potatoes, potato flakes, instant mashed potatoes, 2 potato dumplings, 32 French fries, and 61 potato crisps are reported. In a majority of the samples, free 3-CPD amount was under the limit of detection (< 3 μg/kg) or under the limit of quantification (< 9 μg/kg). Higher concentrations of free 3-CPD were found in potato flakes (37 μg/kg) and seven samples of potato crisps (10.4-46.2 µg/kg). Low concentrations of bound 3-CPD were present in raw potatoes (2 μg/kg), potato flakes (18 µg/kg), mashed potatoes (38 µg/kg) and potato dumplings (10-13 µg/kg). Higher levels of bound 3-CPD occurred in fried potato products. The amount of bound 3-CPD in pre-fried French fries was 27-64 µg/kg, in fried French fries its content was 100-258 µg/kg. In potato crisps, the bound 3-CPD amount was 98-2201 µg/kg. A striking difference was observed between the levels of bound 3-CPD in crisps fried in rapeseed oil and in fractionated palm oil (palmolein). For that reason, the changes were studied of the bound 3-CPD levels in palm oil after heating and in blends of rapeseed and palm oil during frying. It was proven that the frying oils absorbed into the fried potato products represent the main source of bound 3-CPD.

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Optical isomers of chloropropanediols: mechanisms of their formation and decomposition in protein hydrolysates

Cited by 37 publications

References 20 publications

Effects of Degumming and Bleaching on 3‐MCPD Esters Formation During Physical Refining

Effects of Degumming and Bleaching on 3‐MCPD Esters Formation During Physical Refining

What do we know about the molecular mechanism of 3‐MCPD ester formation?

3-Chloropropane-1,2-diol fatty acid esters in potato products

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