96 R. Peinado and J. Mauricio
balance. The increased ADH II activity reflects in increased production of acetalde-
hyde and its derivatives (Berlanga et al. 2001; Cort ́es et al. 1999; Mauricio and
Ortega 1997; Mauricio et al. 2003).
The content in higher alcohols of wine is altered by periodic microaeration; how-
ever, their final contents have been found to be similar to those previously obtained
in wines subjected to traditional biological aging procedures (Cort ́es 2002) The dif-
ferences between traditionally produced wines and wines obtained by microaeration
in stainless-steel vessels are mainly due to the compounds extracted from the cask
wood. Therefore, the aging time can be substantially shortened by combining both
processes (Mu ̃noz 2003; Mu ̃noz et al. 2007).
3B.6 Potential Applications of Flor Yeasts
Because they can grow in such a hostile environment, flor yeasts are highly suitable
for stress-related physiological and genetic studies (Aranda and del Olmo 2003;
Aranda et al. 2002). Flor yeasts are highly tolerant to ethanol and acetaldehyde;
they also possess a high fermentation capacity, so they could be useful for producing
bioethanol. A recent study onethanol tolerance revealed that the increased tolerance
of the flor yeastS. cerevisiaevar.capensisG1 might be a result of an increased
ergosterol content in its plasma membrane (Aguilera et al. 2006).
The usefulness of flor yeasts for the biological aging of red wines has also been
examined (Su ́arez-Lepe and I ̃nigo-Leal 2004). The use of flor films on wine over
short periods may provide a new red wine production technology facilitating the
obtainment of a more uniform colour by formation of pyranoanthocyanin and poly-
meric pigments. Aging times under a flor film must necessarily be short in order
to prevent excessive production of acetaldehyde and unduly altering the olfactive
profile of the red wine as a result (Morata et al. 2007).
One other potential use of flor yeasts is in correcting and preventing browning in
white wines or other types of drinks (Bar ́on et al. 1997; M ́erida et al. 2005).
Future insight into the role of geneFLO11in flor yeasts may be highly use-
ful with a view to advancing cell immobilization technology (Purevdorj-Gage
et al. 2007). So far, oneS. cerevisiaevar.capensisrace has been successfully
co-immobilized withPenicillium chrysogenumin order to obtain biocapsules for
potential use in a number of fermentation processes (Peinado et al. 2006b).
AcknowledgmentsWe would like to acknowledge the financial support from the Ministry of Sci-
ence and Technology (grant AGL2005-01232/ALI) of the Spanish Government, cofinanced with
the European Fund for the Regional Development (FEDER) of the European Union.
References
Aguilera, F., Valero, E., Mill ́an, C., Mauricio, J.C., & Ortega, J.M. (1997). Cellular fatty acid
composition of two physiological races ofSaccharomyces cerevisiaeduring fermentation and
flor veil formation in biological aging of fine wine.Belgian J. Brew. Biotechnol., 2, 39–42.