Study Of Ethyl Carbamate In Fermented Food

Ethyl carbamate (EC) has been classified as a Group2A carcinogen by the World Health Organization’s International Agency for Research on Cancer (IARC), and in fermented cereal products, bean products, fruit juice, wine and fermented tea contain EC. The fermented bean curd and soy sauce as the research object, the pretreatment method of sample and detection method was researched. The objective of this thesis was to stablish an standard method of accurate, economical, environmental, which was suitable for the detection of EC in various fermented foods; the thesis analyzed the content of EC in fermentation food, and studied the changing rule of EC in the fermentation process of fermented bean curd, to provide the scientific basis for establishing the limited standard of EC and improving the security of fermented food.1.By selecting nBC as internal standard, using the quantitative analysis of GC/MS, selecting the standard addition recovery rate as evaluating indicator, and optimizing parameter of EC which was extracted from fermented bean curd and soy sauce by LLE and SLE. The result as follows:Detection EC by GC/MS, the linear was good in the concentration range from20to1500μg/L, the detection limit of EC was4μg/L(S/N>3).By LLE, for fermented bean curd, the optimum volume of dichloromethane was45mL; for soy sauce, the optimum volume of ethyl acetate was45mL. The standard addition was50～800μg/L, the recoveries were65.80%～91.64%; the RSD of intraday detection were2.75%～5.27%, the RSD of interday detection were3.03%～7.22%.By SLE, for fermented bean curd and soy sauce, the best elution solvent was methanol:dichloromethane(1:9), the best volume was40mL. The standard addition was50～800μg/L, the recoveries were88.32%～1.02.60%, the RSD of intraday detection were1.24%～4.67%, the RSD of interday detection were2.13%～6.05%.The results show that the SLE had better repetitive, higher accuracy and less volume of organic solvent; the extracts contained more pigment when extracting EC from soy sauce by LLE, and easy to contaminate ion source. Therefore, SLE was the optimized pretreatment method of detecion EC in fermented bean curd and soy sauce by GC/MS.2. Using the SLE as pretreatment method, and detection EC in fermented bean curd by HPLC-FLD, the study result as follows:Detection EC by HPLC-FLD, the linear was better in the concentration range from100to1500μg/L, the detection limit of EC was30μg/L(S/N≥3). The standard addition was50～800μg/L, the recoveries were71.64%～93.86%, the RSD of intraday detection were1.96%～8.38%, the RSD of interday detection were2.54%～11.42%.The results show that the GC/MS had better repetitive, higher accuracy and less detection limit; the detection limit of HPLC-FLD was much higher and was not for accurate quantitative detecting the trace amounts of EC in fermented foods. Therefore, GC/MS was the optimized detection method of EC in fermented bean curd.3.By SLE-GC/MS, to detection the content of EC in fermented food, the result as follows:The content of EC in fermented bean curd was from not detected to349.99μg/kg; the content of EC in rice wine was from51.13μg/kg to239.42μg/kg; the content of EC in white spirit was from13.73μg/kg to179.50μg/kg; the content of EC in wine was from not detected to32.54μg/kg; the content of EC in soy sauce was from not detected to31.23μg/kg; the content of EC in fermentation sauerkraut from not detected to4.49μg/kg.The standard addition was100～500μg/L in fermented bean curd, rice wine, white spirit, wine, soy sauce and fermentation sauerkraut, the average recovery was93.17%, the RSD of recoveries was2.18%, The results show that SLE-GC/MS can be used to accurate quantitative determination of the content of EC in fermented foods.4. By artificial inoculation fermentation way to make fermented bean curd, analyzed the content of EC in the fermentation process of fermented bean curd urder different conditions, the result as follows:In primary fermentation(temperature was23℃), not detected EC, there were no effects of mucor and rhizopus on the formation of EC in the fermentation process of fermented bean curd. In post-fermentation(temperature was about10℃), not detected EC, there were no effects of red rice, valley liquor and daqu, ethanol content on the formation of EC in the fermentation process of fermented bean curd.The results show that the formation of EC can be avoided by using artificial inoculation fermentation way to make fermented bean curd (inoculation mucor or rhizopus, the primary fermentation temperature was23℃, the post-fermentation temperature was about10℃, add8%salt,2%wine,35chili powder)...