Yuritzel Moreno, Jonathan Martiniuk, Ryan Bailey, Jonah Hamilton, and Vivien Measday*
*The University of British Columbia, 2205 East Mall, Vancouver, BC V6T1Z4, Canada (vivien.measday@ubc.ca)

Spontaneous fermentations are used in the boutique wine industry despite the unpredictable nature of this method compared to inoculated fermentations using single strains of the yeast Saccharomyces cerevisiae. Wines made by spontaneous fermentation may have enhanced aroma and flavor complexity due to the impact of secondary metabolites produced by various non-Saccharomyces (NS) yeasts present on wine grape skins and in the winery environment. Wine and vineyard-associated microbial communities vary in composition by region and are influenced by factors such as climate and viticultural practices, all of which contribute to the unique character or terroir of wines produced by spontaneous fermentation. The Okanagan Valley in British Columbia, Canada is home to over 130 wineries, many of which favor the spontaneous fermentation method as part of their wine portfolio to capitalize on the effects of this unique microbial terroir. The purpose of this study is to identify the NS yeasts isolated from 13 Okanagan Valley vineyards and to evaluate their performance in single and sequentially inoculated fermentations. Pinot noir grape clusters from the Oliver-Osoyoos, Penticton-Naramata, and Kelowna wine subregions were sampled in 2016. Grape samples were spontaneously fermented in the lab and yeast were isolated at various fermentation stages. ITS and D1/D2 28S rDNA Sanger sequencing identified 18 yeast species from 2016, with eight additional species identified from a single Oliver-Osoyoos winery sampled in 2015. Ten NS yeasts were evaluated for fermentation ability by inoculation into Chardonnay grape must, followed by metabolite analyses after 28 days. Sequential fermentations were also conducted with S. cerevisiae and NS yeasts with the most promising fermentative performance and metabolite profiles. These results will help elucidate the unique behavior of indigenous yeasts from the Okanagan Valley that may be candidates for use in commercial-scale sequentially inoculated fermentations.

Funding Support: NSERC Discovery Grant, BC Wine Grape Council