THE YEASTS IN A RIESLING MUST FROM THE NIAGARA GRAPE-GROWING REGION OF ONTARIO

The yeasts in the must from grapes grown in the Niagara Peninsula have been identified and enumerated. The persistence of these indigenous or wild yeasts throughout the fermentation was examined. The number and diversity of yeast species are similar to those reported in other wine districts of the world. The most numerous indigenous species in fresh must were an unknown species of Candida, Hanseniaspora uvarum, Candida diversa and Aureobasidium pullulans. Saccharomyces cerevisiae was not found in the initial 5,000 colony forming units analysed. The first S. cerevisiae was isolated when the alcohol concentration reached 10g/L. S. cerevisiae then increased in numbers throughout the fermentation. At the end of the fermentation only S. cerevisiae was isolated.