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).
