Kinetic modeling of ethyl carbamate formation from urea in Huangjiu during storage

Ethyl carbamate (EC) is a potential carcinogen widely found in various fermented foods and beverages, including Huangjiu (Chinese rice wine). Urea is the main precursor of ethyl carbamate in Huangjiu and the ethyl carbamate concentration increases gradually during storage. In this work, the changes of urea and EC content were investigated during the storage of Huangjiu under different conditions. The results indicated that urea hydrolysis is the dominant mechanism in urea consumption during storage. Then the kinetic models of urea consumption and EC formation were established based on the Arrhenius equation and Eyring equation, respectively. The prediction results of urea and EC concentrations based on these two models were consistent with experimental data, while the model based on the Eyring equation gave a better performance. The corresponding urea control indicators for Huangjiu with different alcohol concentrations under different storage conditions and specific EC benchmark limits can be calculated based on the model. The urea concentration of Huangjiu should be less than 2 mg/L to have a low risk for EC to exceed the standard of 100 mu g/L after storage. Low-temperature storage can slow down and reduce the production of EC. These results are helpful to solve critical problems such as content prediction of urea and EC, condition control for storage and limit standards for EC in Huangjiu.

Automated summary

This study found that urea hydrolysis is the main mechanism of urea consumption during storage of Huangjiu, and established kinetic models for urea consumption and EC formation, determining urea control indicators and EC benchmark limits for Huangjiu. Low-temperature storage can slow down and reduce the production of EC.