Other Ethyl Carbamate Precursors

The prevailing thought regarding the origin of ethyl carbamate in wines seems to be centered on the interaction of urea (and immediate urea precursors such as arginine and citrulline) with ethanol under the acidic conditions found in wine. Thus, appropriate remedial steps have been taken by industry which have considerably lowered levels of ethyl carbamate in wines. However, a seemingly paradoxical situation exists by which wines which have tested negative for the presence of both urea and ethyl carbamate upon leaving the winery, develop considerable levels of ethyl carbamate within a relatively short time. This situation seems to be more prevalent in the case of dessert wines. We have examined the possibility that urea-carbonyl adducts formed prior to fermentation might be responsible. We focused initially on urea-diacetyl adducts. Our research proved conclusively that these diacetyl-urea adducts are not responsible for post-bottling ethyl carbamate formation. We are currently investigating glucose- and fructose-urea adducts.