Changes of ethyl carbamate and its precursors in maesil (Prunus mume) extract during one-year fermentation.

The contents of ethyl carbamate (EC), cyanide, and ethanol were determined in maesil extracts that are liquids generated from fermentation of maesil fruit and brown sugar at 25°C or 15°C for one year. EC was detected from day 150 with a maximum value of 9.7μg/kg. The cyanide levels increased with prolonged soaking time of maesil and decreased at day 150 where EC was firstly detected, indicating that cyanide is a precursor of EC. Ethanol slowly increased at 25°C, while it fluctuated at 15°C. The contents of EC, cyanide, and ethanol were higher in the extracts fermented at 25°C compared with those at 15°C. EC contents had a higher positive correlation with cyanide contents (R=0.658) than ethanol contents (R=0.351). These results indicate that fermenting temperature gave a rise of EC precursors and consequently led to the increase of EC in the maesil extract.