Identification of N-Carbamyl Amino Acids in Wines and in Yeast Cells

¹ Dept. of Viticulture and Enology, University of California, Davis, CA 95616-8749.

N-carbamyl amino acids (NCAAs) were isolated from wines by anion exchange chromatography. Dimethylaminobenzaldehyde (DMAB) was used as color reagent for detection of NCAAs at 438 nm. This color reaction had a detection limit of 0.005 mM and linearity up to 2.5 mM. The isolated NCAAs were further concentrated and then qualitatively identified by silica gel thin layer chromatography (TLC). TLC results indicated that N-carbamyl aspartate (NC-Asp) and N-carbamyl glutamate (NC-Glu) were found in some of the wines tested. By converting NCAAs into their corresponding amino acid hydantoins, it was possible to determine NCAAs quantitatively by an automated HPLC method. NC-Asp was found to range from 0.147 to 0.783 mM in eight wines. Amounts of 0.1 to 0.2 mM of NC-Asp were also found in wines made from a model grape juice. Very low levels of NC-Asp and NC-Glu were detected in yeast cells grown in the model grape juice.

Key words: N-carbamyl amino acids, TLC, HPLC, wine, yeast

Submitted on December 26, 1991