Occurrence and risk assessment of ethyl carbamate in Chinese Baijiu: precursor composition and formation during storage

Ethyl carbamate (EC) is widely present in alcoholic beverages and poses potential health risks. Chinese Baijiu is among the most widely consumed distilled spirits globally; however, systematic investigations into the distribution of EC and its precursors, as well as their formation during storage, remain limited. This study combined a large-scale survey of commercial Baijiu with controlled storage experiments to investigate EC occurrence, precursor composition, and associated health risks. EC was detected in all samples and varied significantly among different flavor types, with Nongxiang-flavor Baijiu exhibiting the highest concentrations. Among the investigated precursors, cyanide showed the strongest association with EC levels. Multivariate analysis further indicated that EC and cyanide jointly represented the primary compositional factors distinguishing Baijiu samples by flavor type. Dietary exposure risk assessment demonstrated that under average consumption conditions, the margin of exposure (MOE) values for Nongxiang- and Jiangxiang-flavor Baijiu were below 10,000, indicating a potential health concern, whereas Qingxiang-flavor Baijiu presented a comparatively lower risk. Storage experiments with freshly distilled Baijiu demonstrated that EC continued to accumulate during aging, accompanied by a progressive decline in cyanide concentration. A consistent inverse correlation between EC and cyanide concentrations was observed across varying storage conditions. Temperature and metal content were found to influence EC formation. These findings highlight the key role of cyanide in EC formation during Baijiu storage and provide a basis for mitigating EC risks through precursor control and optimized storage management.