Influence of Williopsis saturnus yeasts in combination with Saccharomyces cerevisiae on wine fermentation.

AIM

To examine the growth and survival of Williopsis saturnus strains along with wine yeast Saccharomyces cerevisiae in grape must.

METHODS AND RESULTS

For this study, fermentations were performed in sterilized grape must at 18 degrees C. Inoculum level was 5 x 10(6) cells per ml for each yeast. The results showed that W. saturnus yeasts exhibited slight growth and survival depending on the strain, but they died off by day 5. Saccharomyces cerevisiae, however, dominated the fermentation, reaching the population of about 8 log CFU ml(-1). It was observed that ethanol formation was not affected. The concentrations of acetic acid, ethyl acetate and isoamyl acetate were found higher in mixed culture experiments compared to control fermentation. The results also revealed that higher alcohols production was unaffected in general.

CONCLUSION

Fermentations did not form undesirable concentrations of flavour compounds, but production of higher levels of acetic acid in mixed culture fermentations may unfavour the usage of W. saturnus in wine making.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides information on the behaviour of W. saturnus together with S. cerevisiae during the alcoholic fermentation.