Experimental aspects regarding the malolactic fermentation of some red and white wines

Abstract

This scientific paper presents some aspects typical of the process of malolactic fermentation in some wines, respectively, the variation of total, volatile and real acidity (pH), malic acid metabolization and formation of lactic acid, as well as the changes of some composition characteristics (tartaric and citric acids, potassium, calcium, reducing sugars and phenolic compounds). Trials were conducted on seven different wines from the harvest of year 2007: two white wines obtained from Rkaţiteli and Zghihară varieties and five red varieties (Burgund mare, Băbească neagră, Cabernet Sauvignon, Merlot and Fetească neagră). We have studied some wines according to their pH values (3.085, 3.135, 3.264, 3.352, 3.422, 3.470 and 3.505) and total acidity (9.96, 8.84, 7.88, 7.56, 7.25, 6.94, 6.63 g/L C4H6O6), which are significant in the development of the malolactic fermentation. The investigations were carried out under laboratory conditions, for 40 days. For starting the malolactic fermentation, at the end of wine alcoholic fermentation (after 7- 15 days), selected malolactic bacteria (SMB) from the Biolact assortment (Oenococcus oeni class) were added in wines as leaven. By the action of malolactic bacteria, we found in all the studied wines a differentiated diminution (according to the initial values of total acidity and of pH) in the concentration of malic acid, correlated to an increase in the lactic acid content. The modifications of the other composition characteristics sustained the evolution of malolactic fermentation, realised by the great diminution of total acidity and the pH increase, after a certain period (about 16-24 days).