Gas chromatographic determination of amino acid enantiomers in bottled and aged wines

Free l- and d-amino acids were determined by chiral GC-MS in 26 wines, comprising white wines, red wines, ice wines and sparkling wines. The aim of the work was to investigate whether quantities and pattern of d-amino acids, in particular d-proline, correlate with the storage time of bottled wines. The relative quantities with respect to the corresponding l-enantiomer ranged in white wines from 0.4 to 3.9% d-Ala, 0.9-8.3% d-Asx, and 0.5-8.9% d-Glx, in red wines from 2.9 to 10.6% d-Ala, 2.2-10.9% d-Asx, and 3.9-7.4% d-Glx, and in sparkling wines from 2.2 to 9.8% d-Ala, 2.1-4.4% d-Asx and 1.3-6.1% d-Glx. Low relative quantities of 0.3-0.7% d-Pro were detected in three white wines stored for more than 20 years and did not exceed 0.2% d-Pro in two red wines stored for 10 and 20 years, respectively. An ice wine stored for 24 years contained 0.9% d-Pro, 6.4% d-Glx, 3.0% d-Asp and 1.5% d-Ala. The data confirm the presence of d-amino acids in wines. They do not provide evidence for a correlation between the storage time of bottled wines and quantities of d-amino acids.