UREA CONTRIBUTION TO ETHYL CARBAMATE FORMATION IN COMMERCIAL WINES DURING STORAGE

A two-year storage test using commercial wines confirmed that ethyl ca rbamate formation is closely related to the urea content. The ethyl ca rbamate formation rates at 10-degrees-C to 40-degrees-C were represent ed by linear equation against urea concentration in wine. Mathematical evaluation of the equations indicated that urea content in wine shoul d be reduced to less than 2 mg/L in order to keep the ethyl carbamate content within the current target levels of the wine industry: 15 mug/ L in table wines and 60 mug/L in dessert wines. It was found that, upo n storage for six months at 40-degrees-C, ethyl carbamate level of the wines treated with acid urease was significantly lower than that of t he untreated wines. The activation energy to form ethyl carbamate in w ine was found to range between 21 kcal/mol and 28 kcal/mol which is si milar to the activation energy level in other systems such as Japanese sake and simulated wine (a model wine system).