Release of nucleotides and nucleosides during yeast autolysis: kinetics and potential impact on flavor.

Nucleotides, particularly 5'-nucleotides, are important flavoring agents found in many foods and beverages. Their precise effect on the flavor of wines aged on lees has not been examined previously. In this study nucleotides and nucleosides released by yeast during autolysis in a model wine system and in Champagne wines were identified and quantified, and their impact on wine flavor was determined. Ribonucleotides only were detected in yeast autolysate and in Champagne wines. In wines ribonucleotides were quantified by tandem mass spectrometry coupled to HPLC. The maximum concentration of total nucleotides was very low with a maximum of approximately 3 mg/L in wine aged on yeasts for 9 years. In young wines the most important nucleotide was 5'-UMP, but after 2 years of aging its concentration decreased and the concentration of 5'-GMP slowly increased. The threshold values of the most representative nucleotides in Champagne wines were higher than the concentrations found in the same wines. However, it is known that there is synergism between the different nucleotides and also in the presence of glutamic acid. This phenomenon could explain the difference observed in descriptive profiles of wines spiked with nucleotides.