Influence of malolactic fermentation, postfermentative treatments and ageing with lees on nitrogen compounds of red wines

A comparative study was conducted on nine batches of wine taken from the same initial wine, subjected to malolactic fermentation and ageing in barrels, under different technological conditions: malolactic fermentation in barrel or in tank, with or without wine clarification, ageing with or without lees, and stirring or no stirring of the lees. Samples were taken of the initial wine, of the wine at the end of malolactic fermentation, of the wines after clarifying treatments, and after 3, 6, 9, 12 and 14 months of ageing in the barrel, making a total of 51 wines. Only a very small decrease in amino acids was observed during malolactic fermentation, probably due to the wine releasing amino acids produced by the exocellular proteasic activity of the lactic acid bacteria. Ageing of the wine with lees modifies its nitrogen composition because amino acids are released by yeast and bacteria autolysis. The amount of amino acids released was greatest in the wines stirred weekly. All of the wines studied contained low concentrations of biogenic amines.