Qantification And Accumulation Conditions Of Ethyl Carbamate In Soy Sauce

Soy sauce is a kind of popular condiment in Asia countries. As a kind of flavouring substance, it contains large amounts of soluble protein, amino acids, carbonhydrates and so on. But in the fermentation process of soy sauce, small quantities of hazardous substances will be produced. For example, the ethyl carbamate, mycotoxin, dichloropropanol, levulinic acid, 4 methylimidazole and phenolic aldehyde are hazardous substances. In general, the concentrations of these substances in food are very low and have no harm to human health. However, it is hard to control the concentrations of these substances because the raw materials, processing technology and so on. So it would be a potential threat to human health if their concentration exceeds a certain level.A high performance liquid chromatography with fluorescence detection method was developed for the determination of ethyl carbamate (EC) in soy sauce. In order to improve the detection sensitivity, the method of sample pretreatment, derivatization and chromatographic conditions were optimized. The optimal extraction reagent for EC was ethyl acetate. The reaction conditions were as follows: 1.0 mL sample, 200μL of 0.02 mol/L xanthydrol and 100μL of 1.5 mol/L HCl were added into 5 mL test tubes and incubated in the dark for 30 min. The linear determination range of this method was 10 to 200μg/L and the correlation coefficient between EC and the fluorescence response were 0.988. The detectability was 5μg/L which is significantly better than the previous method (20μg/L).EC in different soy sauce were detected. These soy sauce are from different region, and different fermentation process. Results show that the EC concentrations in soy sauce in the south of China were in the range of 40-60μg/L, EC concentrations in soy sauce in central region of China were about 80μg/L, EC concentrations in soy sauce in the north of China were in the range of 20-30μg/L. EC concentrations in soy sauce of sunning fementation method were about 60μg/L, EC concentrations in soy sauce by liquid-state fermentation with high-salt were about 30μg/L, EC concentrations in soy sauce by solid-state fermentation with low-salt were about 80μg/L. The EC in soy sauce of different function has no difference. The concentrations of EC in thick soy sauce were 10% lower than light soy sauce.EC accumuation level was correlated with different fermentation conditions (temperature, salinity and yeast concentration) of soy sauce. Lower temperature of soy sauce fermentation was found to increase the concentrations of precursors (ethanol and urea) with the lower EC concentration. Lower salinity of soy sauce fermentation was found to increase the concentrations of precursors (ethanol and urea) with the lower EC concentration. Under the higher concentration of yeast in soy sauce, with the higher concentration of ethanol, the lower concentration of urea and the lower concentration of EC. It was concluded that low temperature and salinity will reduce EC. But suitable yeast concentration could control the EC in soy sauce.