| Summary: | Little assessment of yeast assemblages has occurred in Canadian wineries, unlike other large wine producing regions (Spain, Italy, Argentina). The aim of this study was to compare yeast assemblages during inoculated and spontaneous fermentations at three Canadian wineries. The wineries (Quails’ Gate Estate Winery, QGEW; Cedar Creek Estate Winery, CCEW; and Road13 Estate Winery, R13EW) are located in the Okanagan wine region, British Columbia. All three wineries have a history of using commercial yeast. During the 2010 vintage, nine inoculated and three spontaneous Vitis vinifera L. var. Pinot noir fermentations were sampled from four distinct stages of fermentation. Yeast populations from inoculated fermentations were also assessed at QGEW during the following vintage in 2011. Saccharomyces cerevisiae isolates were discriminated at the strain level by microsatellite analysis of hyperviariable trinucelotide loci. Non-Saccharomyces species were identified by sequencing the ITS and the D1/D2 domain regions of the large subunit of rDNA. Non-Saccharomyces spp., particularly Henseniaspora uvarum, were the dominant yeasts detected during cold-soak at all three wineries. Spontaneous fermentation appeared to have a greater species/strain diversity/richness than inoculated fermentation at the youngest (R13EW) of the three wineries. Commercial strains were isolated in relatively low frequencies in the spontaneous fermentation at this winery, whereas at the older wineries (QGEW and CCEW) commercial strains dominated fermentation. R13EW was the only winery where the commercial ADY inoculant fully implanted. At QGEW and CCEW, a commercial yeast, Lalvin® ICV-D254, was the major non-inoculant strain detected in both inoculated and spontaneous fermentations. Only QGEW and CCEW reported previous use of this strain in other varietals. Nevertheless, the different wineries exhibited unique yeast species/strain assemblages at all stages of fermentation, even cold-soak. During both vintages studied at QGEW, the non-inoculant ADY strain (Lalvin® ICV-D254) was dominant or co-dominant in inoculated fermentation. Thus, mixed-strain populations in inoculated tanks were observed in both years. This study emphasizes the need for further research on whether the age of a winery is a major factor in affecting the yeast assemblage of fermenting wine, the source(s) of non-inoculant yeast, and the effects yeasts have on the sensorial attributes of the finished wine product. === Irving K. Barber School of Arts and Sciences (Okanagan) === Biology, Department of (Okanagan) === Graduate
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