Changes in amino acid composition of still Chenin blanc wine during ageing on lees

Amino acids are known to affect the aromatic profile of wines, mainly because amino acids contribute to yeast nutrition during winemaking. While the latter has often been addressed in research, studies are lacking regarding the effect of amino acids during wine ageing, even though wine perception depends on a wine’s final composition and probably on its amino acid composition. This study thus aimed to assess changes in the amino acid composition of still Chenin blanc wine during ageing on lees, a process that occurs after alcoholic and malolactic fermentation. In 2021 and 2022, grapes were collected in three vineyards representing different terroirs in the Loire Valley. Fermentation occurred in new and old barrels. After undergoing alcoholic and malolactic fermentation, the wine was aged on lees for six months, and amino acid composition was monitored using LC-MS analysis (direct injection). The results clearly show that amino acid concentration correlated with the week of ageing and vineyard; there was also an effect of the interaction between vintage and barrel age (old vs new). Aspartic acid, proline, and glutamic acid were the main amino acids found in the wines. Globally, three types of changes were seen: most amino acids (including glutamic acid and serine) increased in concentration, some amino acids decreased in concentration (alanine and tryptophan), and one amino acid (Leu) displayed inconsistent patterns.