grapegrowing
many bacteria, but have only recently been described in S. cerevisiae. This type of behavior is dependent on cell number, and often
proceeds when a quorum of microorganisms is reached.
Production of these chemicals has particular poignancy for
the winemaker, as they are well-described aroma compounds in
wine. The most important aroma compound, 2-phenylethanol,
has a "rose water, floral" aroma descriptor. Preliminary evidence from the laboratories at the University of Melbourne has
shown that cellular cross-talk is enhanced during fermentations
with more than one species of yeast. This result indicates that a
wild fermentation—or indeed any fermentation with different
yeast species present—is a dynamic and interacting environment, where the chemical signals also may affect wine aroma.
Summary
Modifying the content of wine is never easy, and the challenge of
increasing ethanol in Australian wines is going to be difficult to
solve. It will involve a few different techniques, where sequential
inoculation of non-Saccharomyces and S. cerevisiae yeasts is just
one strategy. This method provides an innovative and circumspect method to modify ethanol yield in wine without harming
the quality of the product. Indeed, it could be argued that distinctive and unique wines are the main result, with a nod to the
microbial biodiversity that makes it possible. PWV
This text was edited from original publication in the Australian
& New Zealand Grapegrower & Winemaker, February 2013, and is
reproduced here with permission of the publisher, Winetitles.
Dr. Kate Howell is a teaching and research academic at the
University of Melbourne (khowell@unimelb.edu.au).
pr actica l win ery & vin eya rd JU LY 20 13 59
