Grant: Engage Grants Program

Wine is created by the fermentation of sugars in red or white grape juice to ethanol, mainly by the wine yeastSaccharomyces cerevisiae (S. cerevisiae). Two methods are used: spontaneous fermentation, where yeastpresent on the grapes from the vineyard or on winery equipment carry out the fermentative process; andinoculated fermentation, where a commercially prepared, single strain S. cerevisiae inoculum is used.Spontaneously fermented wines are characterized by a diverse succession of yeast species and strains thatvaries by region. They can be more organoleptically complex and have more regional character than winesproduced by inoculated fermentation, but they are subject to greater risk of oxidative yeast spoilage and ifpresent in the winery, commercial S. cerevisiae strain contamination. Central Okanagan winery OkanaganCrush Pad (OCP) uses both methods but prefers to spontaneously ferment their more expensive, higher qualitywines.In this project, we will identify the yeast species (both S. cerevisiae and non S. cerevisiae species) present intheir Summerland Switchback Pinot Gris vineyard using two novel molecular methods: next generationsequencing and microsatellite analysis. We will also compare vineyard yeast populations to yeast populationsin winery spontaneous fermentations. This will allow us to assess the impact of the winery environment onyeast populations in spontaneous fermentations and determine whether commercial S. cerevisiae strains areacting as contaminants. Identifying the beneficial and spoilage yeasts present in the vineyard and winery willenable OCP to modify its hygiene and fermentation protocols to enhance beneficial yeast growth, therebyavoiding costly spoilage and sluggish fermentation issues. This research will also generate more information onyeast ecology in British Columbian wine regions and will likely reveal novel yeast species and strains that canbe exploited in future to enhance the regional character and quality of wine.