Influence of temperature and oxygen concentration on the fermentation behaviour of Candida stellata in mixed fermentation with Saccharomyces cerevisiae

Candida stellata is a wine-yeast species that has been proposed for use as a starter in the wine industry in combination with selected Saccharomyces cerevisiae cultures. To improve our knowledge on the metabolic interactions between these two yeast species, we have investigated the influence of temperature and oxygen concentration on their fermentation behaviour in mixed fermentation. Trials were carried out with free and immobilized C. stellata cells followed by an inoculum of a commercial strain of S. cerevisiae, to determine the biomass evolution and the oenological profiles of the resulting wines. We show that the oxygen concentration does not influence the fermentation behaviour of the C. stellata cells, while a low temperature (16 degrees C) is a critical condition for the metabolic activity of C. stellata in free-cell trials. The immobilization procedures produce a significant improvement in the metabolic activity of C. stellata, with a consequent enhancement of the glycerol content also at the 16 degrees C fermentation temperature. High cell concentrations and the immobilization system appear to positively influence the fermentation behaviour of C. stellata. These results are of interest for the practical application of this process in winemaking.