A series of 25 virgin and refined edible oils, obtained from retailers, was analyzed for levels of free 3-chloropropane-1,2-diol (3-MCPD) and 3-MCPD released from esters with higher fatty acids (bound 3-MCPD). Oils containing free 3-MCPD ranging from <3 microg kg-1 (LOD) to 24 microg kg-1. Surprisingly, bound 3-MCPD levels were much higher and varied between <100 (LOD) and 2462 microg kg-1. On average, virgin oils had relatively low levels of bound 3-MCPD, ranging from <100 (LOD) to <300 microg kg-1 (LOQ). Higher levels of bound 3-MCPD were found in oils from roasted oilseeds (337 microg kg-1) and in the majority of refined oils (<300-2462 microg kg-1), including refined olive oils. In general, it appears that the formation of bound 3-MCPD in oils is linked to preliminary heat treatment of oilseeds and to the process of oil refining. Analysis of unrefined, de-gummed, bleached, and deodorized rapeseed oil showed that the level of bound MCPD decreased during the refining process. However, additional heating of seed oils for 30 min at temperatures ranging from 100 to 280 degrees C, and heating at 230 degrees C (260 degrees C) for up to 8 h, led to an increase in bound 3-MCPD levels. On the other hand, heating of olive oil resulted in a decrease in bound 3-MCPD levels. For comparison, fat isolated from salami was analyzed for intact fatty acid esters of 3-MCPD. This fat contained bound 3-MCPD at a level of 1670 microg kg-1 and the fatty acid esters of 3-MCPD mainly consisted of 3-MCPD diesters; monoesters of 3-MCPD were present in smaller amounts. The major types of 3-MCPD diesters (about 85%) were mixed diesters of palmitic acid with C18 fatty acids (stearic, oleic, linoleic acids). These diesters were followed by 3-MCPD distearate (11%) and 3-MCPD dipalmitate (4%). Generally, very little 3-MCPD existed as the free compound (31 microg kg-1).

S��������� B., N������ O., D������� V., R������ Z., D������ M., V������ J. (2004): Esters of 3-chloropropane-1,2-diol in foodstuffs. Czech J. Food Sci., We provide here for the first time the evidence that 3-chloropropane-1,2-diol (3-MCPD) occurs in foodstuffs in its free form and also in the form of esters with higher fatty acids. These esters represent a new class of food contaminants as 3-MCPD may be released in vivo by a lipase-catalysed hydrolysis reaction. We analysed 20 samples of selected retail food products for their free and bound 3-MCPD content. All samples contained free 3-MCPD at approximately 9.6-82.7 µg/kg food (3 replications, RSD = 0.4-7.0%). The levels of bound 3-MCPD (monoesters and diesters of 3-MCPD with higher fatty acids) found in the foodstuffs analysed varied between the LOD (1.1 mg per kg of fat) and 36.8 mg/kg fat with RSD = 0.3-3.3%. Five foodstuffs of plant origin processed at high temperatures contained elevated levels of bound 3-MCPD (0.14-6.10 mg/kg). A high level of bound 3-MCPD (0.28 mg/kg) was also found in a sample of pickled fish. Some variables potentially influencing the levels of either free or bound 3-MCPD in foodstuffs were determined (pH, water, chlorides, glycerol, fat and its components) and their significance was discussed.

The formation of 3-chloropropane-1,2-diol (3-MCPD) released from its esters with higher fatty acids was studied using the recognised precursors of 3-MCPD (tripalmitin, 1,3-dipalmitin, 1-monopalmitin and soybean oil) in the presence of sodium chloride. The precursors were reacted with sodium chloride in an emulsion stabilised with an emulsifier under conditions which modelled the thermal treatment of foods during processing. The highest amount of bound 3-MCPD (released from its esters) was formed from 1-monopalmitin followed by 1,3-dipalmitin, whereas tripalmitin and soybean oil yielded the lowest levels of bound 3-MCPD. Four sets of experiments were then carried out aimed at monitoring the influence of various factors (soybean oil amount, NaCl content, water content, and temperature) on the yield of bound 3-MCPD. The formation of bound 3-MCPD was directly proportional to the concentration of either oil or NaCl. The highest amount of bound 3-MCPD was formed in media containing approximately 20% water. The amount of bound 3-MCPD decreased with increasing temperature over the range 100&ndash;230&deg;C and reached its highest value at 100&deg;C. Models with 1,2-dipalmitoyl-3-chloropropane-1,2-diol showed that the decomposition rate of this ester rapidly increased with increasing temperature over the range 100&ndash;230&deg;C being the lowest at 100&deg;C and the highest at 230&deg;C. &nbsp;

An improved routine, simple and sensitive method is presented for the determination of free and bound 3-chloropropane-1,2-diol (3-MCPD) in different foods using capillary gas chromatography with mass spectrometric detection and deuterated 3-MCPD as internal standard. The optimised method was linear within the working calibration standard concentrations in the range of 0.009&ndash;1.3 mg 3-MCPD per 1 kg of sample. The LOD and LOQ were 0.003 &micro;g/kg and 0.009 &micro;g/kg, respectively. Validation of the method was carried out by analysing standards of<br /> 3-MCPD, acid-HVP, roasted coffee samples, and the same samples spiked with 3-MCPD. Repeatability (expressed as RSD) of the method was in the range 1.0&ndash;4.2%, the average spike recoveries were 99.1&ndash;99.5% (RSD = 0.8&ndash;1.4%), respectively. 3-MCPD bound in esters with higher fatty acids was isolated as fat, the isolated fat was subjected to methanolysis and 3-MCPD generated was quantified using the same method. The LOD and LOQ were determined to be 1.1 mg/kg of lipids and 3.3 mg/kg of lipids, respectively. Using the optimised method, 20 samples of retail food products were analysed for their free and bound 3-MCPD. All samples contained free 3-MCPD at 9.6&ndash;83 &micro;g/kg (RSD = 0.4&ndash;7.0%). The level of the bound 3-MCPD varied between the LOD and 2.4 mg/kg with RSD = 0.3&ndash;2.4%. &nbsp;

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