Ethyl Carbamate Precursors in Grape Juice and the Efficiency of Acid Urease on Their Removal

Abstract

Non-fermented juices from 15 different grape varieties grown in New York were found to generate 19 to 54 µg/L of ethyl carbamate upon heating at 70°C for 48 hours in the presence of 12% added ethanol. These findings show that ethyl carbamate precursors are present already in the fresh grape juice. Incubation of grape juice with acid urease for four weeks at 37°C did not reduce the amount of ethyl carbamate formed in the presence of alcohol. Urea analyses of the various grape juice showed no detectable amount of urea. Apparently, urea is not a precursor in natural grape juice. No correlation was found between the amount of potential ethyl carbamate and the concentrations of citrulline and arginine.