The Effect of Fermentation and Extended Lees Contact on Ethyl Carbamate Formation in New York Wine

Abstract

A comparison of the ethyl carbamate content of fermented and non-fermented grape juice from five grape varieties grown in New York shows that the non-fermented juice samples produced as much ethyl carbamate as fermented samples. Addition of ethanol to achieve final concentrations of 12%, 16% and 20%, in both fermented and non-fermented samples also resulted in equal amounts of ethyl carbamate. This indicates that in these juices no additional ethyl carbamate precursors were formed during yeast fermentation. These findings suggest that ethyl carbamate precursors exist in the juice which give increasing amounts of ethyl carbamate with increasing concentrations of ethanol alone and that no further precursors are produced by the yeast during fermentation. A series of New York commercial wines were stored for extended periods on yeast lees after completion of the alcoholic fermentation. After the extended lees contact, no increase in ethyl carbamate concentration was found. Apparently, no additional ethyl carbamate precursors were released from the yeast during extended lees contact.