We have developed a wine fermentation procedure
that takes advantage of the metabolic features of a previously
characterizedMetschnikowia pulcherrimastrain in order to
reduce ethanol production. It involves the use of
M. pulcherrima/Saccharomyces cerevisiaemixed cultures,
controlled oxygenation conditions during the first 48 h of
fermentation, and anaerobic conditions thereafter. The influence of different oxygenation regimes and initial inoculum
composition on yeast physiology and final ethanol content
was studied. The impact of oxygenation on yeast physiology
goes beyond the first aerated step and influences yields and
survival rates during the anaerobic stage. The activity of
M. pulcherrimain mixed oxygenated cultures resulted in a
clear reduction in ethanol yield, as compared toS. cerevisiae.
Despite relatively low initial cell numbers,S. cerevisiaealways predominated in mixed cultures by the end of the fermentation process. Strain replacement was faster under low
oxygenation levels.M. pulcherrimaconfers an additional
advantage in terms of dissolved oxygen, which drops to zero
after a few hours of culture, even under highly aerated conditions, and this holds true for mixed cultures. Alcohol reduction