Grant: Engage Grants Program

Primary fermentation of wine occurs when grape sugars are converted to ethanol by the action of yeast, most commonly by Saccharomyces cerevisiae. There are two types of fermentations: spontaneous and guided. In spontaneous fermentation, the must is exposed to the resident yeast population, whereas in guided fermentation, a commercially available S. cerevisiae yeast starter is used as an inoculant. We recently found that yeast fermenting wine must, both in guided and spontaneous fermentations, are usually a mixture of commercial yeasts. These tend to reflect yeasts that have previously been used as inoculum at the winery. The problems we are addressing are that Cedar Creek winery: 1) does not know the yeasts fermenting their wines; and 2) is spending a relatively high amount on commercial yeasts. Knowing the yeasts fermenting the wine will aid Cedar Creek in future yeast-purchasing decisions and will give the winemaker more confidence in using spontaneous fermentation. By knowing the yeast fermenting the wine will lead to intelligent wine-making decisions and an increase in wine quality. These actions will increase the efficiency by which yeasts are used, resulting in cost reductions. The objectives of the collaboration between UBC Okanagan and Cedar Creek Winery are as follows: 1) to foster the development of a new research partnerships between UBC Okanagan and Cedar Creek; 2) to determine the yeast present at 5 different stages; 3) by using the findings, the two partners will determine ways by which cost saving can be achieved. Wine must will be sampled at Cedar Creek winery in October 2012 from Pinot Noir fermentation. Three guided and three spontaneous tanks will be sampled from each of 5 stages. Serial dilutions will be performed and aliquots will be plated onto Yeast Extract Peptone Dextrose agar (YEPD). Twenty-four colonies will be transferred to micro-centrifuge tubes, whereby DNA will be extracted using a Sigma Extraction Kit. The strains will be identified using fragment sizes of 6 microsatellite loci. The DNA fingerprints will be compared to a commercial yeast strain database in order to determine the strains present. Quantities of each yeast strain will be expressed as frequency of occurrence.