Grant: Engage Grants Program

Primary fermentation of wine occurs when grape sugars are converted to ethanol by the action of yeasts, mostcommonly by Saccharomyces cerevisiae. There are two types of fermentations used to produce wine:spontaneous and inoculated. In spontaneous fermentation, the must is exposed to the resident yeast population,whereas in inoculated fermentation, a commercially available S. cerevisiae yeast starter is used. A major stepthat is used by winemakers to aid inoculation is the addition of SO2 prior to spontaneous or commercialinoculation. The problem concerning winemakers is to know what yeasts are fermenting their wine and toknow the optimal SO2 concentration that should be used, i.e., the use of a concentration where only desirableorganisms are present, but allergenic properties and negative health problems associated with residual sulfurare negligible. The goal of the study is to improve the health benefit of wine, but increase wine quality andreduce costs associated with spoilage. The specific objectives are to: 1) foster the development of a newresearch partnership between UBC Okanagan and La Stella winery; 2) determine the yeasts fermenting thewine; and 3) determine the optimum SO2 concentration that should be used for Merlot wine. Merlot wine mustwill be sampled at La Stella winery in September/October 2014 from inoculated and spontaneous fermentationsat 4 different stages (cold-soak, early, mid, and end) and at three SO2 concentrations (0, 20, and 40 ppm). Forspontaneous fermentations, each sulfur treatment will be replicated in triplicate, whereas for inoculatedfermentations, only one tank from each treatment will be sampled. Identification and quantification of bothnon-Saccharomyces species (by Illumina sequencing, not included in this proposal) and S. cerevisiae strains(by microsatellite strain typing) will be made at each stage for each SO2 treatment. Residual sulfur will bemeasured at all stages from each treatment. Chemicals, key to aroma and flavour, will be measured at the endof fermentation (not included in this proposal).