The determination of urea in wine – a review

The concentration of urea in wine is not routinely measured in Australian laboratories, but has been examined in studies of yeast metabolism and the formation of ethyl carbamate, a known carcinogen. For alcoholic beverages that may contain high levels of urea, steps have been taken to reduce the concentration of urea and therefore prevent ethyl carbamate production. Methods for the determination of urea in wine can be grouped into three categories that indicate how selectivity for urea is achieved; those based on colour-forming reactions, enzymatic hydrolysis and chromatographic separation. The two dominant methods used by research groups over the past fifteen years for the determination of urea in wine are based on the urea/ammonia test kit available from Boeringer Mannheim/R-Biopharm and the reaction of urea with 1-phenyl-1,2-propanedione-2-oxime; both are time-consuming and labour-intensive, but involve relatively straightforward and well-established procedures. However, other options are available that may be better suited to the desired application and the instrumentation available in any particular laboratory.