22 F. Z a m o r a
in concentrations between 0.6 and 1.2 g/l and it contributes significantly to the
wine acidity.Saccharomyces cerevisiaealso releases into the wine several other
acids such as lactic acid, isovaleric and isobutyric acids, fatty acids, etc., but only
in low concentrations.It can be concluded that alcoholic fermentation is not only the simple transformation
of sugars into ethanol. On the contrary, it is a very complex process that allows us
to obtain a very pleasant beverage. It represents the transformation of sugars mainly
into ethanol but also into other subproducts, which can contribute positively or neg-
atively to sensory quality. A more complete knowledge about the regulation of all
pathways implied that it is necessary to acquire a better understanding of the process
and of designing strategies to enhance the quality of the product. Moreover, alco-
holic fermentation also implies the transformation of other compounds present in
the grape juice which have a high influence on wine quality. Considerable progress
has been made during recent years and, without doubt, new solutions for new chal-
lenges will be developed in the immediate future (Pretorius 2000; Moreno-Arribas
and Polo 2005).
AcknowledgmentsThe author gratefully acknowledges CICYT (AGL2007-66338 and AGL
2004-02309) for financial support.
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