| Fatty acid esters of chloropropanols are(chloropropanols esters) are pollutants formed by chloropropanols and different fatty acids during the food process. There are many kinds of chloropropanols esters for the diversity of fatty aicds in food, however chloropropanols esters can be classed in four kinds including fatty acid esters of 3-monochloropropane-1,2-diol(3-MCPD esters), 2-monochloropropane-1,3-diol(2-MCPD esters), 1,3-dichloropropan-2-ol(1,3-DCP esters) and 2,3-dichloropropan-1-ol(2,3-DCP esters) according to the combined chloropropanols. Chloropropanols esters exist in many kinds of fatty foods, especially in the refined vegetable oils with the highest pollutant levels. Chloropropanols esters pollution in different foods had been reported in many literatures, especially in foreign literatures, so the human health risk caused by dietary chloropropanols esters exposure has been increasingly aroused people’s concern. Therefore, it is nessessary to set up methods for the detection of chloropropanols esters in different food matrix, and it is also important that to survey the pollution levels of chloropropanols esters in different food items containing fat, and to investigate the health risk of chloropropanols esters for the general population.An optimized system of the detection of chloropropanols esters in different foods containing fat by Gas Chromatography-Mass Spectrometry(GC-MS) combined with th isotope dilution technique was established. The samples were ultrasonically extracted with hexane, followed by ester-bound cleavage reaction with sodium methylate-methanol and purification by solid-supported liquid-liquid extraction, then being derivatived with heptafluoro butyrylimidazol. After extracted by sodium chloride solution, the derivatives were determined by GC-MS. The concentration of chloropropanols esters were quantified by using the deuterium chloropropanols esters as the internal standards. The accuracy of the method was assessed by the recoveries of the blank spiked samples, and the relative standard deviations(RSD) of the recoveries represent the precision of the method. The detection limits of the four kinds of chloropropanols esters in edible vegetable oils, milk power, bread and pastries, sausage, coffee and other samples matrix detected were in the range of 0.002-0.015 mg/kg, and the quantitative limits were in the range of 0.006-0.050 mg/kg. Thw four kinds of chloropropanols esters all showed a good linear relationship in the concentration range of 0.005-0.800 mg/Lwith the correlation coefficients(r) were not less than 0.9995. The recoveries of four kinds of chloropropanols esters in different blank spiked food matrix were in the range of 80.3%-119.0% at the spike levels of 0.025, 0.050, and 0.100 mg/kg with the relative standard deviations(RSDs) not less than 11.4%, which demonstrated the good accuracy and precision of the established method. The results of linearity experiments, recovery experiment demonstrated that the method was the high specificied, sensitive, reliable, and accurate, and suitable for the determination of chloropropanols esters in edible vegetable oils, milk power, bread and pastries, sausage, coffee, etc. The established method was validated by participating in Round T2642 of Food Analysis Performance Assessment Scheme(FAPAS) in 2014, the test results for the vegetable oil provided by FAPAS was acceptable with z score of 1.1, which demonstes the robust and rugness of the established method.The pollution levels of chloropropanols esters in the 337 collected samples including 74 edible vegetable oil samples, 137 milk power samples, 27 bread samples and 35 pastries samples, 29 sausage samples, and 35 coffee samples were investigated by the established GC-MS method. 3-MCPD esters and 2-MCPD esters were detected in most of the samples, and 1,3-DCP esters and 2,3-DCP esters were not detected in all the samples. 3-MCPD esters were detected at a high level in vegetable oils, bread and pastries. The levels of 3-MCPD esters and 2-MCPD esters c in edible vegetable oil were ranged from non-detected(ND) to 10.646 mg/kg with the average value of 1.799 mg/kgand the detection rate of 94.6%, and ND-3.617 mg/kg with the average value of 0.816 mg/kg and the detection rate of 63.6%. The pollution levels of chloropropanols esters in palm oil were the highest among all the vegetable oils, and the second highest levels were found in and rice oil, and the lowest levels were found in in olive oils. The pollutiong levels of 3-MCPD esters and 2-MCPD esters in bread samples ranged from 0.008 to 1.716 mg/kg with the average value of 0.197 mg/kg and the detection rate of 100%) and ND to 0.272 mg/kg with the average value of 0.032 mg/kg and the detection rates of 20.7% for pastries samples. The pollution levels of 3-MCPD esters in majority of milk, sausage, coffee samples relatively low with the concentrations less than 0.010 mg/kg, and 2-MCPD esters were not detected.The preliminary dietary exposure assessments of chloropropanols esters for the general population and the infants were evaluated by combining the dietary intakes acquired from the National Survey of Nutrition and Health Status in 2002 and the pollution levels of the detected food samples in the present study. The average dietary exposure and P97.5 exposure of 3-MCPD esters(calculated as 3-MCPD) for the general Chinese population aroused by the intake of edible vegetable oils were 0.939 mg/kg bw/d and 4.242 mg/kg bw/d, respectively, which accounted for 47.0% and 212.1% of the PMTDI(2 μg/kg bw/d) of 3-MCPD. The average dietary exposure and the P97.5 exposue of 3-MCPD esters for the 6-month old infants were 0.304 mg/kg bw/d and 1.735 mg/kg bw/d, respectively, which accounted for 15.2% and 86.7% of the PMTDI of 3-MCPD. According to the exposure assessment results, the health risk aroused by chloropropanols esters from edible vegetable oil for the general population and the health risk aroused by chloropropanols esters from infant formula for the 6-month old infants were aceptable. However, to protect the public health, the exposure of the high consumption population and the high level contamination food staffs should be given more concern. Furthermore, 2-MCPD esters, as the isomers of 3-MCPD esters, were also detected in many samples at the slightly lower levels than 3-MCPD esters, although there is no health guidance value for 2-MCPD at present, the health risk caused by 2-MCPD esters should not be ignoreed.To explore the formation point of chloropropanols esters during the process procedure of refining oil, the polution levels of chloropropanols esters in raw oils used for the refined edible oils, and the procedural samples from the different process of the refining procedures were detected with the established detection method. The pollution of 3-MCPD esters is widespread in the raw oils, the highest pollution levels of 3-MCPD esters and 2-MCPD esters were all found in raw palm oil samples with the average level was 4.135 mg/kg and 1.582 mg/kg, respectively. The levels of 3-MCPD esters and 2-MCPD esters in the procedural soybean oil and palm oil samples showed an increasing trend in different processing procedures, especially during the process of debromination.. The results acquired in the present study are helpful and will provide basic data for the improvement of the refining procedure of oils. |
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