Selected Saccharomyces yeast strains have been used for more than 150 years
in brewing and for several decades in winemaking. They are necessary in
brewing because of the boiling of the wort, which results in the death of all
yeast cells, with the exception of some Belgian style beers (ex. Lambic),
where the wort is left to be colonized by indigenous yeast and bacteria from
the environment and ferment naturally. In winemaking their use is also
pertinent because they provide regular and timely fermentations, inhibit the
growth of indigenous spoilage microorganisms and contribute to the desired
sensory characters. Even though the use of selected Saccharomyces strains
provides better quality assurance in winemaking in comparison to the unknown
microbial consortia in the must, it has been debated for a long time now
whether the use of selected industrial Saccharomyces strains results in wines
with less sensory complexity and ?terroir? character. In previous decades,
non-Saccharomyces yeasts were mainly considered as spoilage/problematic
yeast, since they exhibited low fermentation ability and other negative
traits. In the last decades experiments have shown that there are some
non-Saccharomyces strains (Candida, Pichia, Kluyveromyces, Torulaspora, etc)
which, even though they are not able to complete the fermentation they can
still be used in sequential inoculation-fermentation with Saccharomyces to
increase sensory complexity of the wines. Through fermentation in a
laboratory scale, we have observed that the overall effects of selected
Torulaspora delbrueckii yeast strains, is highly positive, leading to
products with pronounced sensory complexity and floral/fruity aroma in
winemaking and brewing.
Effect of indigenous S. cerevisiae strains on higher alcohols, volatile acids and esters in wine
